Immunology Flashcards

Question

What are the functions of dendritic cells?

Answer 1

- Express receptors for chemokines and cytokines - Express PRRs - Express Fc receptors for Ig - Capable of phagocytosis - Express cytokines to regulate immune response - Process antigen to T cells in lymph nodes to prime adaptive response

Answer 2

Peripheral tissues

Answer 3

Dendritic cells mature: - upregulate HLA molecules - express costimulatory molecules - migrate via lymphatics to lymph nodes - mediated by CCR7

Answer 4

- Naive lymphocytes enter lymph nodes from blood - Antigens from sites of infection reach lymph nodes via lymphatics - Lymphocytes and lymph return to blood via thoracic duct

Answer 5

Immature cells are adapted for PRR and uptake whilst mature cells are adapted for antigen presentation to prime T cell

Answer 6

- Humoral immunity – B lymphocytes and antibody - Cellular immunity – CD4, CD8 T cells - Cytokines and chemokines

Answer 7

- Wide repertoire of antigen receptors - Exquisite specificity - Clonal expansion - Immunological memory

Answer 8

Anatomical sites of interaction between naïve lymphocytes and microorganisms

Answer 9

- Spleen - Lymph nodes - Mucosal associated lymphoid tissue

Answer 10

- Pre-T cells in bone marrow go to thymus – positive and negative selection of lymphocytes within thymus - T cells are exported as mature T lymphocytes to periphery - Arise from haematopoietic stem cells – exported as immature cells to the thymus where undergo selection - Mature T lymphocytes enter the circulation and reside in secondary lymphoid organs

Answer 11

CD8+ T cells recognise peptide presented by HLA class I molecules CD4+ T cells recognise peptide presented by HLA class II molecules

Answer 12

- Low affinity for HLA – not selected to avoid inadequate reactivity - Intermediate affinity for HLA – positive selection ~10% original cells - High affinity for HLA – negative selection to avoid

Answer 13

- Th1 - Help CD8+ T cells and macrophages - Th17 - Help neutrophil recruitment, enhance generation autoantibodies - Treg - IL-10/TGF beta expressing, CD25+ Foxp3+ - TGh - Follicular helper T cells - Th2 - Helper T cells

Answer 14

- Specialised cytotoxic cells - Recognise peptides derived from intracellular proteins in associations with HLA class I (A,B,C) - Kills cells directly - perforin (pore-forming) and granzymes, expression of Fas ligand - Secrete cytokines e.g. IFN-gamma, TNF-alpha - Defence against viral infections and tumours

Answer 15

Pool of 'memory' T cells ready to respond to antigen - these are more easily activated than naïve cells

Answer 16

Play an important role in promoting germinal centre reactions and differentiation of B cells into IgG and IgA secreting plasma cells.

Answer 17

Subset of lymphocytes that express Foxp3 and CD25

Answer 18

Subset of cells that express CD4 , secrete IFN-gamma and IL-2

Answer 19

Stem cell --> lymphoid progenitors --> Pro B cells --> Pre B cells --> IgM B cells --> IgM plasma cells, IgE, IgA, IgE, IgG

Answer 20

1) No recognition of self = survive | 2) Recognition of self in the bone marrow = negative selection to avoid autoreactivity

Answer 21

1) Dendritic cells prime CD4+ T cells 2) CD4+ T cell help for B cell differentiation - requires CD40L:CD40 3) B cell proliferation, somatic hypermutation, isotype switching

Answer 22

- IgG - IgD - IgE - IgA - J chain - IgM - J chain

Answer 23

Antigen is recognised by the antigen binding regions (Fab) of both the heavy and light chains

Answer 24

It is determined by the constant region of the heavy chain

Answer 25

The heavy chain

Answer 26

- Complement - Phagocytes - Natural killer cells

Answer 27

Primary - big IgM increase, IgG small increase after a lag Secondary - same IgM increase as primary, massive IgG increase Response may be independent of help from CD4+ T lymphocytes

Answer 28

- Dendritic cell - takes up pathogen - processed and primes CD4+ - CD4+ cells help CD8+ and are also primed by dendritic cells. CD8+ recognise intracellular pathogens presented on class I molecules - B cells can also recognise pathogen and produce early response and produce IgM - B cells proliferate by somatic hypermutation - produce high affinity IgG, IgA, IgE

Answer 29

Divalent antibody present within mucous which helps provide barrier to infection

Answer 30

Cell dependent on the presence of CD4+ T cell help for generation

Answer 31

Generated rapidly following antigen recognition and are not dependent on CD4+ T cell help

Answer 32

Carries lymphocytes from lymph nodes back to the blood circulation

Answer 33

Where B cells proliferate and undergo affinity maturation and isotope switching

Answer 34

Site of deletion of T cells with inappropriately high or low affinity for HLA molecules and of maturation of T cells into CD4+ or CD8+ cells

Answer 35

> 20 tightly regulated, linked proteins - produced by the liver, present in circulation as inactive molecules. When triggered, enzymatically activate other proteins in a biological cascade. This results in a rapid and highly amplified response.

Answer 36

Classical (C1,2,4) ---> C3 Central ---> Final common pathway C5-9 ---> Membrane attack complex MBL - mannose-binding leptin (C4,2) ---> C3 Central ---> Final common pathway C5-9 ---> Membrane attack complex Alternative ---> C3 Central ---> Final common pathway C5-9 ---> Membrane attack complex

Answer 37

Holes in bacterial membranes Increase vascular permeability Immune complex = more solution Promote phagocytosis

Answer 38

IgG binding to the pathogen

Answer 39

Small protein messengers Immunomodulatory function Autocrine or paracrine dependent action

Answer 40

Chemokines are subset of cytokines which can recruit homing of leukocytes in inflammatory response i.e. chemoattractants. CCL19 and CCL21 are ligands for CCR7 and dendritic cell trafficking to lymph nodes. Examples include RANTES, IL-8, MIP-1 alpha and beta.

Answer 41

- Malnutrition - Infectious diseases: measles, TB, HIV, SARS-CoV-2 - Environmental stress - Age extremes - Surgery and trauma - Immunosuppressive drugs - Genetic and metabolic diseases

Answer 42

- Infections - Autoimmune conditions (cytopenias) and allergic disease - Persistent inflammation - Cancer (viral associated EBV, HHV-8)

Answer 43

- Small molecules | - JAK inhibitors

Answer 44

Glucocorticoids and mineralocorticoids Cytotoxic agents: methotrexate, mycophenolate, cyclophosphamide and azathioprine Calcineurin inhibitors: cyclosporine and tacrolimus Antiepileptic drugs (phenytoin, carbamazepine, levetiracetam DMARD (sulphasalazine, leflunomide)

Answer 45

Tofacitinib (RA, PA, AS - arthritis treatment) Upadacitinib (PA, RA) Ruxolitinib - JAK2 inhibitor (e.g. myelofibrosis)

Answer 46

Biologics agents: anti-CD20/CD38/BCMA monoclonals, anti-TNF-α protein and receptor antagonists Cellular therapy: anti-CD19/BCMA CAR-T cell therapy Antibody deficiency and bacterial/viral infections are observed with rituximab and other anti-CD20 agents

Answer 47

Risk of infection increased with repeated courses and in patient with a history of B cell malignancy and vasculitis. Anti-TNF agents are linked to reactivation of TB infection

Answer 48

Multiple myeloma Chronic lymphocytic leukaemia Non Hodgkin’s lymphoma Monoclonal gammopathy of uncertain significance

Answer 49

Paraneoplastic syndrome in people who have a thymoma and antibody deficiency: - Combined T and B cell (absent) defect - CMV PJP and muco-cutaneous candida - Autoimmune disease (Pure red cell aplasia, Myasthenia gravis, Lichen planus)

Answer 50

``` Full Blood count Hb < 10g/L neutrophil count lymphocyte count platelet count ``` LFTs, U&Es, protein/albumin, urine protein/Cr ratio, serum protein electrophoresis, serum free light chains Immunoglobulins (IgG, IgA, IgM, IgE ) Serum complement (C3, C4) HIV test (18-80 years) Strategy will pick up to 85% of all immune defects

Answer 51

Protein loosing enteropathy | Prednisolone >10mg/day

Answer 52

Monitor for B cell neoplasm | History of exposure to rituximab

Answer 53

? Primary antibody deficiency

Answer 54

SPE separation of serum proteins by charge Detection of discrete bands: monoclonal identified by immunofixation with labelled IgG, IgA, IgM anti-sera. Monoclonal protein associated with multiple myeloma, WMG, NHL and MGUS SPE can miss free light chain disease which is seen 20% multiple myeloma cases): hence measurement of free light chains is essential for work up of B cell LPD

Answer 55

Tetanus toxoid protein antigen Pneumovax vaccine carbohydrate antigen (all 23 serotypes or to individual pneumococcal serotypes) If vaccine antibody levels are low offer test immunisation with Pneumovax II and tetanus to investigate immune function Failure to respond to vaccination is part of diagnostic criteria for a number of primary antibody deficiency syndromes and is a criteria for receipt of IgG replacement therapy for secondary antibody deficiency syndromes.

Answer 56

CD3+CD4+ T cells CD3+CD8+ T cells CD3-CD56+CD16+ NK cells CD19+ B cells

Answer 57

Analysis of naïve and memory T and B cell subsets Assessment of IgG subclasses Determination of anti-cytokine and complement antibodies: - Anti-Type 1 interferon antibodies (IFN-α and IFN-ω) in SARS-CoV-2 infection - Anti Type 2 interferon antibodies (IFN-γ) in disseminated NTM infection - Anti-GM-CSF antibodies disseminated in cryptococcal infection - Anti-C1 inhibitor antibodies and acquired late onset angioedema ( B cell LPD and SLE) Genetics

Answer 58

Treat underlying cause Advise + education Immunisation against respiratory viruses and bacteria Education to treat bacterial infections promptly: may require higher and longer therapies courses (co-amoxiclav 625mg TDS for 10-14 days rather then 375mg for 5-7 days) Prophylactic antibiotics

Answer 59

Secondary antibody deficiency syndromes: Underlying cause of hypogammaglobinaemia cannot be reversed or reversal is contraindicated OR Hypogammaglobinaemia associated with drugs, therapeutic monoclonal antibodies targeted at B cells and plasma cells, post-HSCT, NHL, CLL, MM or other relevant B-cell malignancy AND Recurrent or severe bacterial infection despite continuous oral antibiotic therapy for 6 months IgG <4.0g/L (excluding a paraprotein/monoclonal protein ) Failure of vaccine response to unconjugated pneumococcal or other polysaccharide vaccine challenge

Answer 60

Member of the lentivirus family: slow evolution of disease Double strand RNA virus Structural, replicative and accessory proteins

Answer 61

- Binds to CD4 and then to chemokine co-receptor CCR5 or CXCR4 - Replicates via a DNA intermediate - Integrates into host genome HIV DNA transcribed to viral mRNA - Viral RNA translated to viral proteins - Packaging and release of mature virus

Answer 62

HIV-1 consists of 4 distinct lineages M, N, O, and P Each lineage arose from independent transmission from chimpanzees (Group M,N,O) and gorillas (O,P) Initial transmission of M subtype to humans occurred in SE Cameroon between 1910-1930. Spread of Group M along Congo river (trains/migration) and established in modern Kinshasa in 1960. Group M virus is pandemic, consists of 9 subtypes and 40 recombinant forms

Answer 63

- Acute - Asymptomatic but progressive - AIDs

Answer 64

Error prone nature of HIV RT, short generation time of viral cycle and length of infection is the driving force for viral diversity Viral mutation has implications for the evasion of CTL immune responses, and emergence of drug resistant virus in patients with inadequate drug treatment Up to 1010 virions are produced every day, source of virus in plasma is recently infected CD4 T cells Integration of HIV provirus in memory CD4 T cells within 72 hours of infection leads to formation of long lived reservoir of latent infection which does not respond to current ART

Answer 65

1. CD4 T cell depletion 2. Chronic immune activation 3. Impairment of CD4 and CD8 T cell function 4. Disruption of lymph node architecture and impaired ability to generate protective T and B cell immune responses 5. Loss of antigen-specific humoral immune responses

Answer 66

Significant increase in HIV-1 viral load in blood ‘Flu like’ symptoms in 70% of cases Significant risk of viral transmission Transient reduction in blood CD4+ T cells Increase in CD8 T cell immune response which coincides with drop in VL CD8 T cell activation (CD38+ and HLA-DR+) Induction of HIV-1 specific antibodies

Answer 67

4TH generation combined HIV-1 antigen/antibody tests will detect infection 1 month post acquisition of infection Assay detect p24 antigen, gp41 from HIV-1 Group O, gp160 envelope protein HIV-1 M and gp36 HIV-2 Rapid point of care HIV-1 tests: result available within 20 minutes less sensitive than 4th generation test HIV-1 RNA tests in cases where HIV-1 serological tests are negative but high clinical suspicion of acute HIV-1 infection HIV-1 RNA and/or DNA tests are used to diagnose infection in children less than 18 months

Answer 68

Full Blood count Renal, liver, bone, lipid profiles and HbA1c Sexual health screen (RPRGU, Hep A, B, C serology) Screen for latent TB using IGRA Baseline chest x ray and ECG Toxoplasma serology

Answer 69

HIV-1 viral load HIV-1 genotype for ART drug resistance HIV-1 tropism test to confirm co-receptor use in HIV-1 in patients who may be candidates for treatment with CCR5 antagonists HLA-B*5701 blood test to avoid prescribing Abacavir and risk of severe hypersensitivity in those with this allele which is seen in 8% of population in NW London Analysis of T cell counts CD4 T cell count and percentage CD4: CD8 T cell ratio

Answer 70

Viral genotype CD8 T cell immune Host genetics (HLA and CCR5) Immune activation

Answer 71

- Infection - PCP - Toxoplasma gondii - Mycobacterium avian complex (MAC disease)

Answer 72

Reverse transcriptase inhibitors NRTI NNRTI Boosted Protease inhibitors Ritonavir + PI Integrase inhibitors DTG, RTG EVG CCR5 antagonist - Maraviroc Fusion inhibitors - T20 (rarely used)

Answer 73

2 NRTI and 1 NRTI or 2NRTI and 1 Integrase inhibitor are standard first line anti-HIV-1 treatments

Answer 74

Berlin and London patient Allogeneic SCT from CCRδ32 HLA matched donor Shock and kill strategy - activate latent CD4+ cell

Answer 75

Primary - inherited – >100 primary immune deficiencies now described – 1:10,000 live births Secondary – acquired – Infection, malignancy, drugs, nutritional deficiencies – Common – May involve more than one component of immune system

Answer 76

– Neonates – Pregnancy – Older age

Answer 77

– Two major or one major and recurrent minor infections in one year – Atypical organisms – Unusual sites – Poor response to treatment

Answer 78

– Family history – Young age at presentation – Failure to thrive

Answer 79

– Essentially identical responses in all individuals – Cells express cytokine/chemokine receptors that allow them to home to sites of infection – Cells express genetically encoded receptors to allow detection of pathogens at site of infection • pattern recognition receptors (Toll-like receptors or mannose receptors) which recognise generic motifs known as pathogen-associated molecular patterns (PAMPs) such as bacterial sugars, DNA, RNA – Cells express Fc receptors to allow them detection of immune complexes – Cells have phagocytic capacity that allows them to engulf the pathogens – Cells secrete cytokines and chemokines to regulate immune response

Answer 80

Toll-like receptors | Mannose receptors

Answer 81

Produced in bone marrow and migrate rapidly to site of injury Release enzymes, histamine, lipid mediators of inflammation from granules.

Answer 82

Monocytes are produced in bone marrow, circulate in blood and migrate to tissues where they differentiate to macrophages. Capable of presenting processed antigen to T cells

Answer 83

``` Liver - Kupffer cell Kidney - Mesangial cell Bone - Osteoclast Spleen - Sinusoidal lining cell Lung - Alveolar macrophage Neural tissue - Microglia Connective tissue - Histiocyte Skin - Langerhans cell Joints - Macrophage like synoviocytes ```

Answer 84

1) Increased neutrophil adhesion and migration into tissues 2) Mobilisation of phagocytes and precursors from bone marrow or within tissues 3) Endothelial cell activation with increased expression of adhesion molecules 4) Phagocytosis of organisms 5) Oxidative and non-oxidative killing 6) Macrophage -T cell communication 7) Cell death and the formation of pus

Answer 85

1. Failure to produce neutrophils 2. Defect of phagocyte migration 3. Failure of oxidative killing mechanisms 4. Cytokine deficiency

Answer 86

– Failure of stem cells to differentiate along myeloid or lymphoid lineage • Reticular dysgenesis – autosomal recessive severe SCID mutation in mitochondrial energy metabolism enzyme adenylate kinase 2 (AK2) – Specific failure of neutrophil maturation • Kostmann syndrome - autosomal recessive severe congenital neutropenia classical form due to mutation in HCLS1-associated protein X-1 (HAX1) • Cyclic neutropenia - autosomal dominant episodic neutropenia every 4-6 weeks mutation in neutrophil elastase (ELA-2)

Answer 87

Leukocyte adhesion deficiency Deficiency of CD18 (b2 integrin subunit) • CD11a/CD18 (LFA-1) is expressed on neutrophils, binds to ligand (ICAM-1) on endothelial cells and so regulates neutrophil adhesion/transmigration • In Leukocyte adhesion deficiency the neutrophils lack these adhesion molecules and fail to exit from the bloodstream • Very high neutrophil counts in blood • Absence of pus formation

Answer 88

Chronic granulomatous disease • Absent respiratory burst – Deficiency of one of components of NADPH oxidase – Inability to generate oxygen free radicals results in impaired killing • Excessive inflammation – Persistent neutrophil/macrophage accumulation – Failure to degrade antigens * Granuloma formation * Lymphadenopathy and hepatosplenomegaly

Answer 89

* Nitrobluetetrazolium (NBT) test * Dihydrorhodamine (DHR) flow cytometry test – Activate neutrophils – stimulate respiratory burst and production of hydrogen peroxide – NBT is a dye that changes colour from yellow to blue, following interaction with hydrogen peroxide – DHR is oxidised to rhodamine which is strongly fluorescent, following interaction with hydrogen peroxide

Answer 90

• Nitrobluetetrazolium(NBT)test • Dihydrorhodamine (DHR) flow cytometry test – Activate neutrophils – stimulate respiratory burst and production of hydrogen peroxide – NBT is a dye that changes colour from yellow to blue, following interaction with hydrogen peroxide – DHR is oxidised to rhodamine which is strongly fluorescent, following interaction with hydrogen peroxide

Answer 91

IL12, IL12R, IFNg or IFNg R deficiency: ``` • IL12 - IFNg network important in control of mycobacteria infection – Infection activates IL12- IFNg network • Infected macrophages stimulated to produce IL12 • IL12 induces T cells to secrete IFNg • IFNg feeds back to macrophages & neutrophils • Stimulates production of TNF • Activates NADPH oxidase • Stimulates oxidative pathways ```

Answer 92

Bacterial infections • Staphylococcus aureus • Enteric bacteria Fungal infections • Candida albicans • Aspergillus fumigatus and flavus Atypical Mycobacteria • Mycobacterial infection • Mycobacterium tuberculosis

Answer 93

``` Aggressive management of infection – Infection prophylaxis • Antibiotics – eg Septrin • Anti-fungals – eg Itraconazole – Oral/intravenous antibiotics as needed ``` ``` Definitive therapy – Haematopoietic stem cell transplantation • ‘Replaces’ defective population – Specific treatment for CGD • Interferon gamma therapy ```

Answer 94

Classical NK deficiency - Absence of NK cells within peripheral blood - Abnormalities described in GATA2 or MCM4 genes in subtypes 1 and 2 Functional NK deficiency - NK cells present but function is abnormal - Abnormality described in FCGR3A gene in subtype 1

Answer 95

- No good trial data - Prophylactic antiviral drugs such as acyclovir or gancyclovir - Cytokines such as IFN-alpha to stimulate NK cytotoxic function - Haematopoietic stem cell transplantation in severe phenotypes

Answer 96

• > 20 tightly regulated, linked proteins – produced by liver – Present in circulation as inactive molecules • When triggered, enzymatically activate other proteins in a biological cascade – Results in rapid, highly amplified response

Answer 97

C1, C4, C2 * Formation of antibody- antigen immune complexes * Results in change in antibody shape – exposes binding site for C1 * Binding of C1 to the binding site on antibody results in activation of the cascade * Dependent upon activation of acquired immune response (antibody)

Answer 98

* Activated by the direct binding of MBL to microbial cell surface carbohydrates * Directly stimulates the classical pathway, involving C4 and C2 but not C1 * Not dependent on acquired immune response

Answer 99

• Bacterial cell wall fails to regulate low level of spontaneous activation of alternate pathway – eg lipopolysaccharide of gram negative bacteria – teichoic acid of gram positive bacteria • Not dependent on acquired immune response • Involves factors B, D and Properidin • Factor H – control protein

Answer 100

* Activation of C3 is the major amplification step in the complement cascade * Triggers the formation of the membrane attack complex via C5-C9

Answer 101

- Increases vascular permeability and cell trafficking to site of inflammation - Activates phagocytes - Opsonisation of pathogens to promote phagocytosis - Promotes clearance of immune complexes - Punches holes in bacterial membranes

Answer 102

Complement deficiency – Susceptibility to bacterial infections, especially encapsulated bacteria • Neisseria meningitides – esp properidin and C5-9 deficiency • Haemophilus influenzae • Streptococcus pneumoniae ``` Classical pathway deficiency (C2, C1q) - Susceptibility to SLE - Failure of phagocytosis of dead cells • Increased nuclear debris - Failure to clear immune complexes - Immune complex deposition in blood vessels ``` MBL deficiency MBL2 mutations are common but not usually associated with immunodeficiency

Answer 103

Meningococcal septicaemia

Answer 104

Active SLE leads to consumption of C3 and C4 Active lupus causes persistent production of immune complexes and consequent consumption of complement leading to functional complement deficiency

Answer 105

* Nephritic factors are auto- antibodies directed against components of the complement pathway * Nephritic factors stabilise C3 convertases resulting in C3 activation and consumption * Often associated with glomerulonephritis (classically membranoproliferative) * May be associated with partial lipodystrophy

Answer 106

• Complement deficiency can lead to SLE – Deficiency of early components of the classical pathway, C1q and C2, predisposes to development of SLE and conversely.. • Auto-immune disease can lead to complement deficiency – SLE in someone with a normal complement system will lead to consumption of complement – Autoantibodies directed against components of the complement pathway may lead to consumption of complement (usually C3)

Answer 107

Quantitation of complement components – C3, C4 routinely measured – Other components not routinely quantified Functional complement tests – CH50 classical pathway – AP50 alternative pathway

Answer 108

- Vaccination - Boost protection mediated by other arms of the immune system - Meningovax, Pneumovax and HIB vaccines - Prophylactic antibiotics - Treat infection aggressively - Screening of family members

Answer 109

- Most severe form of severe combined immunodeficiency (SCID) - Mutation in mitochondrial energy metabolism enzyme adenylate kinase 2 (AK2) - Fata; in early life if not corrected by bone marrow transplant

Answer 110

X-linked severe combined immunodeficiency (SCID) is an inherited disorder of the immune system that occurs almost exclusively in males. 45% of all severe combined immunodeficiency

Answer 111

Mutation of common gamma chain on chromosome Xq13.1: • Shared by cytokine receptors for IL-2, IL-4, IL-7, IL-9, IL-15 and IL-21 • Inability to respond to cytokines causes early arrest of T cell and NK cell development and production of immature B cells Phenotype • Very low or absent T cell numbers • Very low or absent NK cell numbers • Normal or increased B cell numbers but low Igs

Answer 112

Adenosine deaminase deficiency (ADA deficiency) is an inherited condition that damages the immune system and is a common cause of severe combined immunodeficiency (SCID). 16.5% of all severe combined immunodeficiency

Answer 113

Adenosine Deaminase Deficiency • Enzyme required for cell metabolism in lymphocytes Phenotype • Very low or absent T cell numbers • Very low or absent B cell numbers • Very low or absent NK cell numbers

Answer 114

1) Active transport of maternal IgG across placenta 2) IgG in colostrum 3) Neonatal production of IgG

Answer 115

``` • Unwell by 3 months of age • Infections of all types • Failure to thrive • Persistent diarrhoea • Unusual skin disease - colonisation of infant’s empty bone marrow by maternal lymphocytes - graft versus host disease • Family history of early infant death ```

Answer 116

22q11.2 deletion syndrome e.g. DiGeorge syndrome * TBX1 may be responsible for some features * Usually sporadic rather than inherited * Normal numbers B cells * Reduced numbers T cells * Homeostatic proliferation with age * Immune function usually only mildly impaired and improves with age

Answer 117

Defect in one of the regulatory proteins involved in Class II gene expression: – Regulatory factor X – Class II transactivator Absent expression of MHC Class II molecules Profound deficiency of CD4+ cells – Usually have normal number of CD8+ cells – Normal number of B cells – Low IgG or IgA antibody due to lack of CD4+ T cell help BLS type 1 also exists due to failure of expression of HLA class I

Answer 118

* Unwell by 3 months of age * Infections of all types * Failure to thrive * Family history of early infant death

Answer 119

* Cytokine production – IFN * Cytokine receptors – IL12 receptor * Cytotoxicity * T-B cell communication

Answer 120

T cell deficiency: – Viral infections • Cytomegalovirus – Fungal infection • Pneumocystis, Cryptosporidium – Some bacterial infections – esp intracellular organisms • Mycobacteria tuberculosis, Salmonella – Early malignancy

Answer 121

- Total white cell count and differential - Lymphocyte subsets - Immunoglobulins - Functional tests of T cell activation and proliferation - HIV test

Answer 122

• Aggressive prophylaxis/treatment of infection • Haematopoieitic stem cell transplantation – To replace abnormal populations in SCID – To replace abnormal cells - class II deficient APCs in BLS • Enzymereplacementtherapy – PEG-ADA for ADA SCID • Genetherapy – Stem cells treated ex-vivo with viral vectors containing missing components. Transduced cells have survival advantage in vivo. • Thymic transplantation – To promote T cell differentiation in Di George syndrome – Cultured donor thymic tissue transplanted to quadriceps muscle

Answer 123

1) Dendritic cells prime CD4+ T cells 2) CD4+ T cell help for B cell differentiation required CD40L:CD40 3) B cell proliferation somatic hypermutation - isotype switching to IgG, A , E

Answer 124

Soluble proteins made up of two heavy and two light chains: – Heavy chain determines the antibody class • IgM, IgG, IgA, IgE, IgD, • Subclasses of IgG and IgA also occur – Antigen is recognised by the antigen binding regions (Fab) of both heavy and light chains – Effector function is determined by the constant region of the heavy chain (Fc)

Answer 125

* Abnormal B cell tyrosine kinase (BTK) gene Pre B cells cannot develop to mature B cells * Absence of mature B cells * No circulating Ig after ~ 3 months

Answer 126

• Boys present in first few years of life • Recurrent bacterial infections – Otitis media, sinusitis, pneumonia, osteomyelitis, septic arthritis, gastroenteritis • Viral, fungal, parasitic infections – Enterovirus, Pneumocystis, • Failure to thrive

Answer 127

* Normal number circulating B cells * Normal number of T cells but activated cells do not express CD40 ligand * No germinal centre development within lymph nodes and spleen * Failure of isotype switching * Elevated IgM * Undetectable IgA, IgE, IgG

Answer 128

– Marked reduction in IgG, with low IgA or IgM – Poor/absent response to immunisation – Absence of other defined immunodeficiency

Answer 129

``` – Recurrent bacterial infections • Pneumonia, persistent sinusitis, gastroenteritis • Often with severe end-organ damage – Pulmonary disease • Interstitial lung disease • Granulomatous interstitial lung disease (also LN, spleen) • Obstructive airways disease – Gastrointestinal disease • Inflammatory bowel like disease • Sprue like illness • Bacterial overgrowth ``` ``` Autoimmune disease • Autoimmune haemolytic anaemia or thrombocytopenia • Rheumatoid arthritis • Pernicious anaemia • Thyroiditis • Vitiligo ``` – Malignancy • Non-Hodgkin lymphoma

Answer 130

Selective IgA deficiency Prevalence = 1:600 2/3rd individuals asymptomatic 1/3rd have recurrent respiratory tract infections Genetic component, but cause as yet unknown

Answer 131

Antibody deficiency (or CD4 T cell deficiency): ``` – Bacterial infections • Staphylococcus, streptococcus – Toxins • Tetanus, diptheria – Some viral infections • Enterovirus ```

Answer 132

* Total white cell count and differential * Lymphocyte subsets * Serum immunoglobulins and protein electrophoresis * Production of IgG is surrogate marker for CD4 T cell helper function * Functional tests of B cell function

Answer 133

• Aggressive prophylaxis / treatment of infection • Immunoglobulin replacement if required – Derived from pooled plasma from thousands of donors – Contains IgG antibodies to a wide variety of common organisms – aim of maintaining IgG levels within the normal range – Treatment is life-long • Immunisation – For selective IgA deficiency – Not otherwise effective because of defect in IgG antibody production

Answer 134

A tissue graft from a donor of the same species as the recipient but not genetically identical

Answer 135

Phase 1: recognition of foreign antigens Phase 2: activation of antigen-specific lymphocytes Phase 3: effector phase of graft rejection

Answer 136

Most relevant protein variations in clinical transplantation – 1. ABO blood group (for ABO-incompatible transplantation) 2. HLA (human leukocyte antigens) Some other determinants – minor histocompatibility genes

Answer 137

Two major components to rejection: – T cell-mediated rejection – Antibody-mediated rejection (B cells)

Answer 138

* Major Histocompatibility complex (MHC) (chromosome 6) found in humans * Cell surface proteins

Answer 139

* HLA Class I (A,B,C)– expressed on all cells * HLA Class II (DR, DQ, DP) – expressed on antigen- presenting cells but also can be upregulated on other cells under stress

Answer 140

* To maximise diversity in defense against infections/neoplasia, each individual has a variety of HLA * Each individual’s HLA are derived from a large pool of population varieties

Answer 141

Parent to child: ≥3/6 matched Sibling to sibling: 25% - 6MM 50% - 3MM 25% - 0MM

Answer 142

* T-cell mediated | * Antibody-mediated (B cells)

Answer 143

Phase 1 - presentation of donor HLA by a professional antigen presenting cell (APC), in the context of recipient HLA Phase 2 – T cell activation, inflammatory cell recruitment Phase 3 – effector phase (organ damage)

Answer 144

``` – Release of toxins to kill target Granzyme B – Punch holes in target cells Perforin – Apoptotic cell death Fas-Ligand ```

Answer 145

Phase 1 – B cells recognise foreign HLA Phase 2 - proliferation and maturation of B cells with anti-HLA antibody production Phase 3 – effector phase; antibodies bind to graft endothelium = intra-vascular disease

Answer 146

- Neutralisation of microbe and toxins - Opsonisation and phagocytosis of microbes - Antibody-dependent cellular cytotoxicity - Lysis of microbes - Phagocytosis of microbes opsonised with complement fragments - Inflammation

Answer 147

Anti-HLA antibodies are not naturally occurring: – Pre-formed – transplantation, pregnancy, transfusion – Post-formed - arise after transplantation

Answer 148

* A and B glycoproteins on red blood cells but also endothelial lining of blood vessels in transplanted organ * Naturally occurring anti-A and anti-B antibodies

Answer 149

3 types of assay – Cytotoxicity assays – Flow cytometry – Solid phase assays

Answer 150

``` Anti-CD20 BAFF inhibitors Proteosome inhibitors Complement inhibitors CD28/B7 blockade Anti-CD40 ```

Answer 151

Drug toxicity --> reduce dosage Viral infections --> reduce dosage Vascular disease --> BP control, vascular stent Post transplant lymphoproliferative disease --> reduce dosage and start chemo Recurrent glomerulonephritis --> depends on GN

Answer 152

IgE mediated type 1 hypersensitivity reaction

Answer 153

Microbial: Microbial PAMP -> recognition of microbial structure -> Th1, Th17 immune response Allergens Allergen -> recognition by change in function e.g. loss of tissue function/disrupted epithelial barrier -> Th2 immune response

Answer 154

Innate lymphoid cells found at mucosal barriers (skin, respiratory and the gastrointestinal tract) which lack antigen specific receptors Respond to a number of inflammatory cytokines (IL-33, TSLP, IL-25) IL-1 and IL-12 family cytokines member CD4 ILC classified into ILC1, ILC2, ILC3, based on their cytokine production and transcriptional profiles with ILC1s, ILC2s, and ILC3s resembling CD4+ T helper (Th)1, Th2 and Th17/22 cells, respectively.

Answer 155

ILC2 secrete IL-4, IL-5, IL-9, IL-13 and amphiregulin (AREG) Secretion of type 2 cytokines by ILC2 implicated in allergic asthma, allergic rhinitis AD, food allergy and eosinophilic oesophagitis Amphiregulin paly an important role in epithelial barrier repair in skin and respiratory tract In allergic disease overcome steady state inhibition exerted by tissue CD4 T regulatory cells

Answer 156

Signature cytokines are IL-4, IL-5, IL-13 Helps B cells to produce IgE (IL-4) Expands and activate eosinophils (IL-5) Stimulate mucous secretion (IL-13) Role in host defense against helminths, parasites and tissue repair Contribute to late stage tissue damage in allergic disease

Answer 157

Distinct CD4 T subset characterised by expression of the lineage determining transcription factor GATA-3 and the signal transduction protein STAT-6

Answer 158

Eliminate pathogens by secretion of cytotoxic granules, RNAase proteins and extracellular traps Implicated in late stage tissue damage in atopic dermatitis, asthma, eosinophilic oesophagitis, and granulomatous disease

Answer 159

IgE function Protection against helminth and parasitic infection IgE induces mast and basophil degranulation associated with immediate hypersensitivity (allergic) reactions

Answer 160

IgE binds to high affinity receptor (FceR1) on mast cells, basophils, eosinophils and DC IgE also binds to ‘low affinity’ (FceR2) receptor on above cells as well as B cells, respiratory and gastrointestinal epithelial cells

Answer 161

2 main subtype in human: MC (Tryptase T) skin MC (Chymotryptase CT) in airways

Answer 162

Role in immediate and late phase immune responses to helminths, bacteria Play an important role in allergic disorders

Answer 163

1) IgE/IgG receptors which respond to antibody-antigen cross linking 2) G-protein-coupled receptors which are ligands for soluble mediators (complement and drugs)

Answer 164

FcReR1(IgE) FceR1 and FceR1IA (IgG) MRGPRX2 (opiates, quinolones) Cytokine receptors (Il-4, IL-9)

Answer 165

1) Recruitment of soluble proteins and inflammatory cells to site of infection 2) Increase in rate of lymphatic flow back to regional lymph nodes 3) Smooth muscle contraction in lungs and gut (may help to expel pathogens) and activation of sensory neurones (itch, sneeze)

Answer 166

1) Release of pre-formed inflammatory mediators from granules (histamine) 2) Release and synthesis of lipid mediators (leukotrienes, prostaglandins) 3) Synthesis of proinflammatory cytokines

Answer 167

Antigen dose Length of exposure Physical properties of allergen Route of exposure

Answer 168

Source Small water soluble proteins Carbohydrate Resistance to heat, digestive enzymes

Answer 169

Oral exposure promotes immune tolerance (IgA and IgG) whereas skin and respiratory induces IgE sensitisation

Answer 170

Defects in skin epithelial barrier (atopic dermatitis) are a significant risk factor for development of IgE antibodies. Stressed or damage epithelial cells secrete IL-25, IL-33, GM-CSF and TSLP which act on tissue immune cells (DC, basophils, type 2 innate lymphoid cells) and neurons to induce Th2 cells immune responses (IL-4, IL-5, IL-9, IL-13)

Answer 171

IL-4 plays a crucial role in development of Th2 immune responses and is only induced following peptide-MHC presentation to naïve/memory Th2 cells

Answer 172

Rapid onset of symptoms within 4 hours caused by release of inflammatory mediators following allergen cross linking of IgE on surface of mast cells and basophils Delayed symptoms result from CD4T2 cell (IL-4, IL-5, IL-13) immune responses and eosinophil related tissue damage

Answer 173

Early oral exposure will protect against development of peanut allergy Sensitisation to peanut and wheat can occur from exposure through the skin Differences in preparation of peanuts (roast promotes IgE whereas boiled IgG)

Answer 174

Allergen specific IgE (Sensitisation) Tests - Skin prick and intradermal test, IgE blood tests Functional allergen tests: In vitro tests Basophil activation Serial mast cell tryptase Ex vitro tests Open or blinded allergen challenge

Answer 175

Occurs within minutes or up to 3-4 hours after exposure to allergen Skin: angioedema (swelling of lips, tongues, eyelids) , urticaria ( wheals or ‘hives’), flushing and itch Respiratory tract: cough, SOB wheeze, sneezing, nasal congestion and clear discharge, red itch watery eyes Gastrointestinal tract: nausea, vomiting and diarrhoea Blood vessels and Brain: symptoms of hypotension (faint, dizzy, blackout) and a sense of impending doom

Answer 176

A positive test is indicated by a wheal ≥ 3mm greater than the negative control High positive and negative predictive and positive skin for aeroallergens Allergen extracts labile for some fruit and vegetables: : prick-prick test: food and SPT Antihistamines and some anti-depressants should be discontinued for at least 48 hours beforehand

Answer 177

Application of positive, negative controls and allergens into the skin More sensitive but less specific than SPT Best used to follow up negative venom and drug allergy test (better than blood tests) Can be used if SPT to allergen is negative but convincing history Labour intensive, greater risks of anaphylaxis

Answer 178

3 major providers 1) Phadia 2) Siemens 3) Hycor All assays have excellent technical performance

Answer 179

Concentration: higher levels more likely to be associated with symptoms Molecular target within whole extract or even individual epitope can be linked to symptoms Affinity (strength of binding) to target: higher affinity associated with risk Capacity of IgE antibody to induce mast/basophil degranulation

Answer 180

No access to SPT and/or IDT Patients who can’t stop anti-histamines Patients with a history of dermatographism, extensive eczema Patient with a history of anaphylaxis Decision on who needs food challenge Prediction for resolution of egg, milk, wheat allergy Monitor response to anti-IgE therapy

Answer 181

Nuts - Storage proteins (2 s albumins): severe reactions Pathogenesis-related proteins (PR10 bet v1 homologue) which are also found in tree pollens, fruits and vegetables: mild reaction Non specific lipid transfer proteins which are also found in in fruit (peach) , tree pollen (plane), vegetables and legumes ( can be mild or severe) Wheat Omega-5-gliadin bettermarker of specific wheat allergy than total wheat IgE Egg and milk Heat stable proteins ovomucoid (egg) and caseins (estimate who outgrow allergy) Fish and shellfish Parvalbumin in fish, Tropomyosin in crustaceans (cross reactive)

Answer 182

A biomarker for anaphylaxis: Tryptase: pre-formed protein found in mast cell granules Systemic degranulation of mast cells during anaphylaxis results in increase in serum tryptase Peak concentration at 1-2 hours; returns to baseline by 6-12 hours Failure to return to baseline after anaphylaxis may be indicative of systemic mastocytosis Useful if diagnosis of anaphylaxis is not clear (hypotension + rash during anaesthesia) Reduced sensitivity for food induced anaphylaxis

Answer 183

Measurement of basophil response to allergen IgE cross linking Activated basophils increase the expression of CD63, CD203, CD300 protein on cell surface Increasing use in diagnosis of food and drug allergy: surrogate marker for challenge tests Efforts to standardise test to use by diagnostic laboratories to reduce need for challenge tests

Answer 184

Challenge tests

Answer 185

Limited to oral cavity, swelling and itch: only 1-2% cases progresses to anaphylaxis

Answer 186

Fevers / malaise seen in primary EBV Abscess formation Sacroiliac joint inflammation in an individual with axial spondyloarthritis Anaemia due to red cell haemolysis secondary to anti-red cell antibodies

Answer 187

Local factors at sites predisposed to disease lead to activation of innate immune cells such as macrophages and neutrophils, with resulting tissue damage (innate)

Answer 188

Aberrant T cell and B cell responses in primary and secondary lymphoid organs lead to breaking of tolerance with development of immune reactivity towards self-antigens Organ-specific antibodies may predate clinical disease by years Adaptive immune response plays the predominant role in clinical expression of disease

Answer 189

Auto-inflammatory - monogenic + polygenic Mixed - polygenic Auto-immune - monogenic + polygenic

Answer 190

An alteration in DNA that occurs after conception.

Answer 191

Auto-inflammatory - innate Mixed - mixed innate/adaptive Auto-immune - adaptive

Answer 192

Mutations in a gene encoding a protein involved in a pathway associated with innate immune cell function Abnormal signalling via key cytokine pathways involving TNF-alpha and/or IL-1 is common

Answer 193

Periodic fevers Skin/joint/serosal/CNS inflammation High CRP

Answer 194

Muckle Wells Syndrome MWS Familial mediterranean fever FMF TNF receptor associated periodic syndrome TRAPS Hyper IgD with periodic fever syndrome HIDS

Answer 195

The inflammasome is a multiprotein intracellular complex that detects pathogenic microorganisms and sterile stressors, and that activates the highly pro-inflammatory cytokines interleukin-1b (IL-1b) and IL-18. Inflammasomes also induce a form of cell death termed pyroptosis.

Answer 196

Autosomal recessive condition Mutation in MEFV gene MEFV gene encodes pyrin-marenostrin Pyrin-marenostrin expressed mainly in neutrophils Failure to regulate cryopyrin driven activation of neutrophils

Answer 197

Periodic fevers lasting 48-96 hours associated with: Abdominal pain due to peritonitis Chest pain due to pleurisy and pericarditis Arthritis Rash

Answer 198

AA amyloidosis - liver produces serum amyloid A as acute phase protein Serum amyloid A deposits in kidneys, liver, spleen Nephrotic syndrome

Answer 199

High CRP, high SAA | Blood sample to specialist genetics laboratory to identify MEFV mutation

Answer 200

Colchicine 500ug bd - binds to tubulin in neutrophils and disrupts neutrophil functions including migration and chemokine secretion IL-1 blocker (anakinra, canukinumab) TNF alpha blocker

Answer 201

Mutation in a gene encoding a protein involved in a pathway associated with adaptive immune cell function Abnormality of regulatory T cells - IPEX Abnormality of lymphocyte apoptosis - ALPS

Answer 202

Immune dysregulation, polyendocrinopathy, enteropathy, X- linked syndromeI

Answer 203

Mutations in Foxp3 transcription factor (Forkhead box p3) which is required for development of Treg cells Failure to negatively regulate T cell responses Autoreactive B cells limited repertoire of autoreactive B cells

Answer 204

Diabetes Mellitus Hypothyroidism Enteropathy

Answer 205

Mutations within FAS pathway Eg mutations in TNFRSF6 which encodes FAS Disease is heterogeneous depending on the mutation Defect in apoptosis of lymphocytes Failure of tolerance Failure of lymphocyte ‘homeostasis’

Answer 206

High lymphocyte numbers with large spleen and lymph nodes Auto-immune disease - commonly auto-immune cytopenias Lymphoma

Answer 207

Mutations in genes encoding proteins involved in pathways associated with innate immune cell function Local factors at sites predisposed to disease lead to activation of innate immune cells such as macrophages and neutrophils, with resulting tissue damage HLA associations are usually less strong In general these disease are not characterised by presence of auto-antibodies Familial association studies and twin studies suggested genetic predisposition to disease

Answer 208

NOD2 gene mutations are present in 30% patients (ie not necessary) IBD1 gene on chromosome 16 identified as NOD2 (CARD-15, caspase activating recruitment domain -15) NOD2 expressed in cytoplasm of myeloid cells - macrophages, neutrophils, dendritic cells Intracellular receptor for muramyl dipeptide on bacterial products and promotes their clearance Mutations also found in patients with Blau syndrome and some forms of sarcoidosis

Answer 209

``` Expression of pro-inflammatory cytokines/chemokines Leukocyte recruitment Release of proteases, free radicals Focal inflammation in/around crypts Formation of granulomata Tissue damage with mucosal ulceration ```

Answer 210

Corticosteroid | Anti-TNF alpha antibody

Answer 211

Mutations in genes encoding proteins involved in pathways associated with innate immune cell function and adaptive immune cell function HLA associations may be present Auto-antibodies are not usually a feature

Answer 212

Highly heritable - 90% of the risk of developing disease is genetic Enhanced inflammation occurs at specific sites where there are high tensile forces (entheses - sites of insertions of ligaments or tendons) Low back pain and stiffness Enthesitis Large joint arthritis

Answer 213

Highly heritable - 90% of the risk of developing disease is genetic Enhanced inflammation occurs at specific sites where there are high tensile forces (entheses - sites of insertions of ligaments or tendons) Low back pain and stiffness Enthesitis Large joint arthritis

Answer 214

HLA B27 - Presents antigen to CD8 T cells. Ligand for killer immunoglobulin receptor IL23R - Receptor for IL23 which promotes differentiation of Th17 cells ILR2 - Decoy receptor that inhibits activity of IL1

Answer 215

Non-steroidal anti-inflammatory drugs Immunosuppression Anti-TNF alpha Anti-IL17

Answer 216

Mutations in genes encoding proteins involved in pathways associated with adaptive immune cell function HLA associations are common Aberrant B cell and T cell responses in primary and secondary lymphoid organs lead to breaking of tolerance with development of immune reactivity towards self-antigens Auto-antibodies are found

Answer 217

PTPN 22 - Protein tyrosine phosphatase non-receptor 22 suppresses T cell activation - found in SLE, T1DM, RA CTLA4 - Cytotoxic T lymphocyte associated protein 4 Expressed by T cells and transmits inhibitory signal to control T cell activation - found in SLE, T1DM, RA, autoimmune thyroid disease

Answer 218

``` Goodpasture disease - HLA-DR3 - 10x risk Graves disease - HLA-DR3 - 4x risk Systemic lupus erythematosus - HLA-DR3 - 6x risk Type I diabetes - HLA-DR3/4 - 25x risk Rheumatoid arthritis - HLA-DR4 - 4x risk ```

Answer 219

Type I: Anaphylactic hypersensitivity - Immediate hypersensitivity which is IgE mediated – rarely self antigen Type II: Cytotoxic hypersensitivity - Antibody reacts with cellular antigen Type III: Immune complex hypersensitivity - Antibody reacts with soluble antigen to form an immune complex Type IV: Delayed type hypersensitivity - T-cell mediated response

Answer 220

1) Antibody dependent destruction (NK cells, phagocytes, complement) 2) Receptor activation or blockage (sometimes

Answer 221

Autoantibodies can bind to receptors and cause: 1) Antibody dependent destruction (NK cells, phagocytes, complement) 2) Receptor activation or blockage (sometimes called type V reaction)

Answer 222

Goodpasture disease Pemphigus vulgaris Graves disease Myaesthenia gravis

Answer 223

Goodpasture disease - Noncollagenous domain of basement membrane collagen type IV - glomerulonephritis, pulmonary haemorrhage Pemphigus vulgaris - Epidermal cadherin - skin blistering Graves disease - Thyroid stimulating hormone (TSH) receptor - hyperthyroid Myaesthenia gravis - acetylcholine receptor - muscle weakness

Answer 224

1) Immune complex formation and deposition in blood vessels 2) Complement activation and infiltration of macrophages and neutrophils 3) Cytokine and chemokine expression, granule release from neutrophils, increased vascular permeability 4) Inflammation and damage to vessels, cutaneous vasculitis, glomerulonephritis, arthritis

Answer 225

DNA, Histones, RNP | Presents as rash, glomerulonephritis, arthritis

Answer 226

1) HLA class I molecules present antigen to CD8 T cells 2) Cytolytic granule release from primed CD8 T cell 3) TNF induction, HLA upregulated, inflammation, tissue damage

Answer 227

Insulin dependent diabetes mellitus - pancreatic beta-cell antigen, beta-cell destruction: CD8+ T-cells

Answer 228

Excessive production of thyroid hormones Mediated by IgG antibodies which stimulate the TSH receptor - agonist so triggers TSH production

Answer 229

Commonest cause of hypothyroidism in iodine-replete areas Goitre – enlarged thyroid infiltrated by T and B cells Associated with anti-thyroid peroxidase antibodies Some shown to induce damage to thyrocytes Associated with presence of anti-thyroglobulin antibodies

Answer 230

- Many women >65 have anti-thyroid antibodies - Some postmenopausal women with anti-thyroid antibodies have subclinical hypothyroidism - Small proportion of postmenopausal women with anti-thyroid antibodies have overt hypothyroidism

Answer 231

CD8 T-cell mediated type IV pathology – recognise autoantigens presented by MHC Class I molecules on beta cells

Answer 232

Anti-islet cell antibodies Anti-insulin antibodies Anti-GAD antibodies Anti-IA-2 antibodies

Answer 233

Anti-islet cell antibodies Anti-insulin antibodies Anti-GAD antibodies Anti-IA-2 antibodies Individuals with 3-4 of the above are highly likely to develop type I diabetes

Answer 234

Antibodies against gastric parietal cells which secrete intrinsic factor, or antibodies against intrinsic factor itself. Intrinsic factor not able to absorb B12 as well - B12 deficiency.

Answer 235

Pernicious anaemia - Anti-intrinsic factor antibody, Anti-gastric parietal cell antibody Coeliac - Anti-TTG (anti-tissue transglutaminase antibody), Anti-endomyosial antibody UC>Crohn's - P-ANCA (anti-neutrophil cytoplasmic antibody, perinuclear staining) Autoimmune hepatitis - P-ANCA (anti-neutrophil cytoplasmic antibody, perinuclear staining), ANA (anti-nuclear antibodies) SMA (smooth muscle antibodies) Anti-LKM (antibodies vs liver kidney microsomal proteins) Primary biliary cholangitis - AMA (anti-mitochondrial antibody P-ANCA (anti-neutrophil cytoplasmic antibody, perinuclear staining), ANA (anti-nuclear antibodies)

Answer 236

Fluorescein conjugated polyclonal anti-human immunoglobulin UV source - fluorescence microscope

Answer 237

Myaesthenia Gravis - AChR antibody Myaesthenia Gravis with myositis - Anti-striational antibody Neuromyelitis optica spectrum disorder (NMOS) - Anti-AQP4 (aquaporin) Optic neuritis, encephalomyelitis - Anti-MOG (myelin oligodendrocyte glycoprotein) Encephalitis (may be malignancy associated) - Anti-NMDA receptor (Anti-N-methyl D-aspartate (NMDA) receptor) Seizures (may be malignancy associated) - Anti-GABA receptor (gamma aminobutyric acid receptor)

Answer 238

Goodpasture disease - Anti-glomerular basement membrane (GBM) antibody ANCA associated vasculitis - Microscopic polyangiitis / Eosinophilic granulomatosis with polyangiitis - P-ANCA (anti neutrophil cytoplasmic antibody, perinuclear staining, anti-myeloperoxidase) ANCA associated vasculitis - Granulomatosis with polyangiitis - C-ANCA (anti-neutrophil cytoplasmic antibody, cytoplasmic staining, anti-proteinase 3)

Answer 239

HLA DR4 (DRB1 0401, 0404, 0405) and HLA DR1 (DRB1 0101) alleles - Susceptible alleles share a sequence at positions 70-74 of the HLA DR beta chain These alleles may bind ‘arthritogenic peptides’ and have been shown to bind to citrullinated peptides with high affinity Peptidyl arginine deiminase (PAD)2 and PAD4 polymorphisms - Polymorphisms are associated with increased citrullination This creates a high load of citrullinated proteins PTPN22 polymorphism

Answer 240

Smoking associated with development of erosive disease Smoking associated with increased citrullination Gum infection with Porphyromonas gingivalis associated with rheumatoid arthritis P gingivalis is only bacterium known to express PAD enzyme and thus promote citrullination

Answer 241

Antibodies to cyclic citrullinated peptide Bind to peptides in which arginine has been converted to citrulline by peptidylarginine deiminase (PAD) Around 95% specificity for diagnosis of rheumatoid arthritis Around 60-70% sensitivity for diagnosis of rheumatoid arthritis

Answer 242

A rheumatoid factor is an antibody directed against the common (Fc) region of human IgG IgM anti-IgG antibody is most commonly tested although IgA and IgG rheumatoid factors may also be present in some individuals Around 60-70% specificity and sensitivity for diagnosis of rheumatoid arthritis

Answer 243

Group of antibodies that bind to nuclear proteins Test by staining of Hep-2 cells (human epidermoid cancer line)

Answer 244

Abnormalities in clearance of apoptotic cells - Polymyorphisms in genes encoding complement, MBL, CRP Abnormalities in cellular activation - Polymorphisms in genes expressing of cytokines, chemokines, co-stimulatory molecules, intracellular signalling molecules B cell hyperactivity and loss of tolerance Antibodies directed at intracellular proteins ? Debris from apoptotic cells that have not been cleared Nuclear antigens - DNA, histones, snRNP Cytoplasmic antigens - Ribosome, scRNP

Answer 245

Antibodies bind to antigen to form immune complexes Immune complexes deposit in tissues Skin, joints, kidney Immune complexes activate complement (classical pathway) Immune complexes stimulate cells expressing Fc and complement receptors

Answer 246

LN - type III - immune complexes deposit in basement membrane Goodpasture's disease - type II - antibody specific for the basement membrane (rather than immune complexes) deposit

Answer 247

dsDNA Ro, La, Sm, U1RNP - Ribonucleoproteins SCL70 - Topoisomerase Centromere

Answer 248

Homogeneous staining associated with specificity for dsDNA

Answer 249

Are highly specific for SLE (95%) - Occur in ~60-70% of SLE patients - Very high titres = more severe disease including renal or CNS - Useful in disease monitoring False positive results unusual (<3%)

Answer 250

Associated with antibodies to extractable nuclear antigens | Specificity is for some ribonucleoproteins (Ro, La, Sm, U1RNP) – confirm with ELISA

Answer 251

Ro, La, Sm, RNP (all are ribonucleoproteins) - Antibodies may occur in SLE - Anti-Ro and La are also characteristically found in Sjogren’s syndrome - Titres not helpful in monitoring disease

Answer 252

Formation of antibody-antigen immune complexes activate complement cascade via classical pathway complement components become depleted if constantly consumed Quantitation of C3 and C4 acts as a surrogate marker of disease activity

Answer 253

Inactive disease - normal C3, C4 Active disease - normal C3, low C4 Severe active disease - low C3, C4

Answer 254

Recurrent venous or arterial thrombosis Recurrent miscarriage May be associated with livedo reticularis, cardiac valve disease May occur alone (primary) or in conjunction with autoimmune disease (secondary)

Answer 255

Three antibody tests: 1) Lupus anti-coagulant Cannot be assessed if the patient is on anticoagulant therapy 2) Anti-cardiolipin antibody Antibody specific for negatively charged phospholipids 3) Anti-B2 glycoprotein 1 antibody Antibody specific for glycoprotein found associated with negatively charged phospholipids

Answer 256

``` Calcinosis Raynauds Esophageal dysmotility Sclerodactyly Telangiectasia ```

Answer 257

Skin involvement does progress beyond forearms - CREST features - More extensive gastrointestinal disease - Interstitial pulmonary disease - Scleroderma kidney/renal crisis

Answer 258

Limited cutaneous systemic sclerosis: Anti-centromere antibodies ``` Diffuse cutaneous systemic sclerosis: Nucleolar pattern Anti-topoisomerase antibodies (Scl70) RNA polymerase Fibrillarin ```

Answer 259

Dermatomyositis Within muscle – perivascular CD4 T cells and B cells Immune complex mediated vasculitis Polymositis Within muscle – CD8 T cells surround HLA Class I expressing myofibres CD8 T cells kill myofibres via perforin/granzymes

Answer 260

``` Positive ANA (in some patients) – extended myositis panel ``` 1) Anti-aminoacyl transfer RNA synthetase antibody eg Jo-1 (cytoplasmic) 2) Anti-signal recognition peptide antibody (nuclear and cytoplasmic) (PM) 3) Anti-Mi2 (nuclear) (DM>PM)

Answer 261

Small vessel vasculitis associated with ANCA – 3 types: Microscopic polyangiitis/Microscopic polyarteritis/MPA Granulomatosis with polyangiitis/Wegener’s granulomatosis/GPA Eosinophilic granulomatosis with polyangiitis/Churg-Strauss syndrome/eGPA

Answer 262

Antibodies specific for antigens located in primary granules within cytoplasm of neutrophils Inflammation may lead to expression of antigens on cell surface of neutrophils Antibody engagement with cell surface antigens may lead to neutrophil activation (type II hypersensitivity) Activated neutrophils interact with endothelial cells causing damage to vessels - vasculitis

Answer 263

cANCA Cytoplasmic fluorescence Associated with antibodies to enzyme proteinase 3 Occurs in > 90% of patients with granulomatous polyangiitis with renal involvement p-ANCA Perinuclear staining pattern Associated with antibodies to myeloperoxidase Less sensitive and specific than cANCA Associated with microscopic polyangiitis and eosinophilic granulomatous polyangiitis

Answer 264

cANCA Cytoplasmic fluorescence Associated with antibodies to enzyme proteinase 3 Occurs in > 90% of patients with granulomatous polyangiitis with renal involvement p-ANCA Perinuclear staining pattern Associated with antibodies to myeloperoxidase Less sensitive and specific than cANCA Associated with microscopic polyangiitis and eosinophilic granulomatous polyangiitis

Answer 265

Adaptive immunity

Answer 266

Dendritic cell Macrophage B lymphocyte (Macrophages include Langerhans cells, mesangial cells, Kupffer cells, osteoclasts, microglia etc.)

Answer 267

Clonal expansion following exposure to antigen: T cells with appropriate specificity -> proliferate and differentiate into effector cells (cytokine secreting, cytotoxic) B cells with appropriate specificity will proliferate and differentiate to T cell independent (IgM) (memory and) plasma cells undergo germinal centre reaction and differentiate to T cell dependent IgG/A/E(M) memory and plasma cells Plasma cells secrete high affinity specific antibodies Immunological memory: Pre-formed pool of high affinity specific antibodies Residual pool of specific T and B cells with enhanced capacity to respond if re-infection occurs

Answer 268

CD8+ and CD4+ cell level drop - but there's still a detectable level in the blood

Answer 269

Longevity Memory T cells are maintained for a long time without antigen by continual low-level proliferation in response to cytokines Different pattern of expression of cell surface proteins involved in chemotaxis / cell adhesion These allow memory cells to access non-lymphoid tissues, the sites of microbial entry. Rapid, robust response to subsequent antigen exposure There are more memory cells These cells are more easily activated than naïve cells

Answer 270

Pre-formed antibody Circulating high affinity IgG antibodies Longevity Long lived memory B cells and plasma cells Rapid, robust response to subsequent antigen exposure Memory B cells are more easily and rapidly activated than naïve cells

Answer 271

MEMORY – preformed antibodies, memory T cells, memory B cells, to provide protective immunity No adverse reactions Practical considerations – one shot, easy storage, inexpensive

Answer 272

Hemagglutinin (HA) is the receptor-binding and membrane fusion glycoprotein of influenza virus and the target for infectivity - neutralising antibodies

Answer 273

BCG – bacilli Calmette-Guerin: Attenuated, strain of bovine tuberculosis Some protection against primary infection Some protection against progression to active TB T cell response is important in protection

Answer 274

Live organism | Modified, (attenuated) organism to limit pathogenesis

Answer 275

MMR BCG Yellow fever Typhoid (oral) Polio (Sabin oral) Influenza (Fluenz tetra for children 2-17 years)

Answer 276

- Raises immune response - protect against strains - Activates all phases of immune system. T cells, B cells – with local IgA, humoral IgG - May confer lifelong immunity, sometimes just after one dose

Answer 277

Possible reversion to virulence (recombination, mutation). Vaccine associated paralytic poliomyelitis (VAPP, ca. 1: 750,000 recipients) Spread to contacts Spread to immunosuppressed/immunodeficient patients Storage problems

Answer 278

- Conjugate to protein carrier | - Adjuvant

Answer 279

Enhances T cell immunity: Polysaccharide plus protein carrier Polysaccharide alone induces a T cell independent B cell response – transient Addition of protein carrier promotes T cell immunity which enhances the B cell/antibody response Haemophilus Influenzae B Meningococcus Pneumococcus (Prevenar)

Answer 280

Adjuvant increases the immune response without altering its specificity - improved innate response Mimic action of PAMPs (pathogen associated molecular patterns) on TLR (toll-like receptors) and other PRR (pattern recognition receptors) Aluminium salts (humans) Lipids – monophosphoryl lipid A (humans HPV) Oils -Freund’s adjuvant (animals)

Answer 281

1) mRNA - covid virus has spike proteins which bind to ACE2 = infection - spike proteins expressed on T cells 2) Adenoviral vector vaccines - DNA inserted into vector (Sputnik vaccine vector) --> translation

Answer 282

Acquired defects in DC maturation and function associated with some malignancy suggests a rationale for using ex vivo–generated DC pulsed with tumour antigens as vaccines Focus on tumour associated antigens or mutational antigens

Answer 283

e.g. Sipuleucel-TProvenge Personalised therapy after white cells removed and exposure to antigen, then infused into patient

Answer 284

Primary antibody deficiency: X linked agammaglobulinaemia X linked hyper IgM syndrome Common variable immune deficiency ``` Secondary antibody deficiency: Haematological malignancies Chronic lymphocytic leukaemia Multiple myeloma After bone marrow transplantation ```

Answer 285

- Hepatitis B immunoglobulin – needle stick/bite/sexual contact – from HepBSag+ve individual - Rabies immunoglobulin – to bite site following potential rabies exposure - Varicella Zoster immunoglobulin – women <20 weeks pregnancy or immunosuppressed where aciclovir or valaciclovir is contraindicated - Tetanus immunoglobulin – no specific preparation available in UK – use IVIG for suspected tetanus

Answer 286

T cells transferred after they have been removed, exposed to antigen, then reinserted: Virus specific T cells Tumour infiltrating T cells (TIL – T cell therapy) T cell receptor T cells (TCR - T cell therapy) Chimeric antigen receptor T cells (CAR – T cell therapy)

Answer 287

T cells with chimeric receptors targeting CD19 Patient’s own T cells Genetically engineered to express receptor Expanded in vitro Used for acute lymphoblastic leukaemia in children Used for some forms of non-Hodgkin lymphoma

Answer 288

T cells (CD28, CTLA4) and APC (CD80, CD86) interaction: Ipilimumab antibody binds to CTLA4 and blocks immune checkpoint, allowing T cell activation

Answer 289

Very effective in conditions like metastatic melanoma Can cause autoimmunity because of the interference in checkpoint

Answer 290

Pembrolizumab and Nivolumab

Answer 291

Antibody binds to PD-1 on T cell interacting with PD-ligand 1 and 2 on APC Blocks immune checkpoint Allows T cell activation

Answer 292

Advanced melanoma | Metastatic renal cell cancer

Answer 293

Interleukin 2 – stimulate T cell response Renal cell cancer Interferon alpha 2a – immunomodulatory effect Behcet’s Interferon alpha – antiviral effect Hepatitis B Hepatitis C (with ribavirin) Interferon gamma – enhance macrophage function Chronic granulomatous disease

Answer 294

Phospholipase A2 - Breaks down phospholipids to form arachidonic acid which is converted to eicosanoids (e.g. prostaglandins, leukotrienes) by cyclo-oxygenases Corticosteroids inhibit phospholipase A2 - Blocks arachidonic acid and prostaglandin formation and so reduces inflammation

Answer 295

1) Decreased traffic of phagocytes to inflamed tissue Decreased expression of adhesion molecules on endothelium Blocks the signals that tell immune cells to move from bloodstream and into tissues Results in transient increase in neutrophil counts 2) Decreased phagocytosis 3) Decreased release of proteolytic enzymes

Answer 296

Lymphopenia Sequestration of lymphocytes in lymphoid tissue Affects CD4+ T cells > CD8+ T cells > B cells Blocks cytokine gene expression Decreased antibody production Promotes apoptosis

Answer 297

- Cyclophosphamide - Mycophenolate - Azathioprine

Answer 298

Action - Inhibit DNA synthesis - Cells with rapid turnover most sensitive Toxicity - Bone marrow suppression - Infection - Malignancy - Teratogenic

Answer 299

Toxic to proliferating cells Bone marrow depression Hair loss Sterility (male>>female) Haemorrhagic cystitis Toxic metabolite acrolein excreted via urine Malignancy Bladder cancer Haematological malignancies Non-melanoma skin cancer Infection Pneumocystis jiroveci

Answer 300

Bone marrow suppression Cells with rapid turnover (leucocytes and platelets) are particularly sensitive 1:300 individuals are extremely susceptible to bone marrow suppression Thiopurine methyltransferase (TPMT) polymorphisms Unable to metabolise azathioprine Check TPMT activity or gene variants before treatment if possible; always check full blood count after starting therapy Hepatotoxicity Idiosyncratic and uncommon Infection Serious infection less common than with cyclophosphamide

Answer 301

Bone marrow suppression Infection Cells with rapid turnover (leucocytes and platelets) are particularly sensitive Infection Particular risk of herpes virus reactivation Progressive multifocal leukoencephalopathy (JC virus)

Answer 302

Goodpasture syndrome Severe acute myasthenia gravis Antibody mediated transplant rejection/ABO incompatible

Answer 303

Inhibit T cell proliferation/function and prevents upregulation of IL-2 Used in: Transplantation SLE Psoriatic arthritis

Answer 304

Inhibit T cell proliferation and function Used in: Transplantation

Answer 305

Inhibitors of cell signallingJAK inhibitors Inhibit JAK-STAT signalling (associated with cytokine receptors) Influences gene transcription Inhibits production of inflammatory molecules Effective in Rheumatoid arthritis, psoriatic arthritis, axial spondyloarthritis

Answer 306

Apremilast Inhibition of PDE4 leads to increase in cAMP Influences gene transcription via protein kinase A pathway Modulates cytokine production Effective in psoriasis and psoriatic arthritis

Answer 307

``` Drugs T cells: Rabbit anti-thymocyte globulin Basiliximab – anti-CD25 Abatacept – CTLA4-Ig ``` B cells Rituximab – anti-CD20 Lymphocyte migration Vedolizumab – anti-a4b7 integrin Actions include - Block signalling - Cell depletion - Inhibit migration

Answer 308

Indications and dosing - Allograft rejection (renal, heart) - Daily intravenous infusion Action – multiple modes - Lymphocyte depletion - Modulation of T cell activation - Modulation of T cell migration Toxicity - Infusion reactions - Leukopenia - Infection - Malignancy

Answer 309

Antibody directed at CD25 (IL-2Ra chain) Indications and dosing Prophylaxis of allograft rejection Intravenous given before and after transplant surgery Action Blocks IL-2 induced signalling and inhibits T cell proliferation Toxicity Infusion reactions - Infection - Concern re long term risk malignancy

Answer 310

CTLA4–Ig fusion protein Indications and dosing: - Rheumatoid arthritis - Intravenous 4 weekly - Subcutaneous weekly Action - Reduces costimulation of T cells via CD28 Toxicity - Infusion reactions - Infection (TB, HBV, HCV) - Caution wrt malignancy

Answer 311

Antibody specific for CD20 Indications and dose - Lymphoma - Rheumatoid arthritis - SLE - 2 doses intravenous every 6-12 months (RA) Action - Depletes mature B cells Toxicity - Infusion reactions - Infection (PML) - Exacerbation CV disease

Answer 312

Antibody specific for a4b7 integrin Indications and dosing - Inflammatory bowel disease - Intravenous every 8 weeks Action - Inhibits leukocyte migration Toxicity - Infusion reactions - Hepatotoxic - Infection (? PML) - Concern re malignancy

Answer 313

TNFa is a pivotal cytokine in inflammation in many conditions TNFa blockade used in Rheumatoid arthritis, Psoriasis and psoriatic arthritis, Inflammatory bowel disease, Familial Mediterranean fever

Answer 314

Infliximab, Adalimumab, Certolizumab, Golimumab

Answer 315

``` Indications and dosing - Rheumatoid arthritis - Ankylosing spondylitis - Psoriasis and psoriatic arthritis Inflammatory bowel disease - Subcutaneous or intravenous ``` Toxicity - Infusion or injection site reactions - Infection (TB, HBV, HCV) - Lupus-like conditions - Demyelination - Malignancy

Answer 316

Inhibits TNFa and TNFb Indications and dosing: - Rheumatoid arthritis - Ankylosing spondylitis - Psoriasis and psoriatic arthritis - Subcutaneous weekly Toxicity: - Injection site reactions - Infection (TB, HBV, HCV) - Lupus-like conditions - Demyelination - Malignancy

Answer 317

IL-6 plays an important role in inflammation in rheumatoid arthritis IL-6 blockade using an anti-IL6 receptor antibody is effective in management of rheumatoid arthritis (and Castleman's disease)

Answer 318

Tocilizumab | Sarilumab

Answer 319

IL23 – IL17 pathway important in spondyloarthritides and related conditions Axial spondyloarthritis (AS), Psoriasis and psoriatic arthritis, Inflammatory bowel disease (not anti-IL17 for IBD)

Answer 320

IL-23 - IL-23 comprises p40+p19 Indications and dosing - Psoriasis, psoriatic arthritis - Subcutaneous every 8 weeks Action - Inhibits IL-23 Toxicity - Injection site reactions - Infection (TB) - Concern re malignancy

Answer 321

IL-4, IL-5 and IL-13 are key cytokines in Th2 and eosinophil responses IL-4/13 blockade using an antibody specific for the IL4 receptor alpha subunit may be used for eczema and asthma Anti-IL13 antibody may be used for management of eczema Anti-IL5 antibody is used for eosinophilic asthma

Answer 322

Indications and dosing - Osteoporosis - Subcutaneous every 6 months Action - Inhibits RANK mediated osteoclast differentiation and function Toxicity - Injection site reactions - Infection – mildly immunosuppressive - Avascular necrosis of jaw

Answer 323

Infusion reactions Urticaria, hypotension, tachycardia, wheeze – IgE mediated Headaches, fevers, myalgias – not classical type I hypersensitivity Injection site reactions Peak reaction at ~48 hours May also occur at previous injection sites (recall reactions) Mixed cellular infiltrates, often with CD8 T cells Not generally IgE or immune complexes

Answer 324

John Cunningham Virus (JCV) - Common polyomavirus that can reactivate - Infects and destroys oligodendrocytes - Progressive multifocal leukoencephalopathy - Associated with use of multiple immunosuppressive agents