Immunology Flashcards

Question

What are the common phagocyte deficiency?

Answer 1

Neutrophils are the chief phagocyte Function to isolate, engulf and kill pathogens Express adhesion receptors and complement receptors to facilitate uptake of opsonised dangerous elements. Defects in neutrophils (function or number) Account for nearly 20% PIDs Include chronic granulomatous disease, Chediak-Higashi syndrome, Griscelli syndrome, leukocyte adhesion deficiency, neutrophil granule deficiency, myeloperoxidase deficiency, cyclic neutropenia, severe congenital neutropenia (Kostmann syndrome) & x-linked neutropenia. Can be secondary too Myeloperoxidase deficiency G6PD deficiency Both present with similar presentations to CGD but milder forms. Diagnosis by measuring enzyme levels Leukocyte adhesion deficiency Rare Inability of leukocytes to localise to sites of inflammation due to defective adherence mechanisms. 3 types Clinical manifestations vary but all have defect in CD18 present on surface of leukocytes CD18 is the beta chain of 3 integrin receptors – LFA-1, MAC-1 and P15-/95 Complete deficiency of CD18 results in death in early life but those with partial defects benefit from prophylactic and acute antibiotics BMT may be required Chediak-Higashi syndrome Abnormal neutrophil granules and defective killing Oculocutaneous albinism, neurological symptoms and increased pyogenic infections Can develop unchecked inflammation HSCT can cure immunological defects but not neurological symptoms Griscelli syndrome Global pigmentary dilution with sivery gray hair Abnormal management of intracellular granules Pyogenic infections HSCT can cure immunologic abnormalities

Answer 2

Defect in NADPH oxidase complex resulting in inability to produce respiratory burst. Several components of NADPH complex encoded by different genes One of these is on x chromosome so can get x-linked and autosomal recessive forms Failure to kill micro-organism leads to granuloma formation Key features Early presentation – usually Abscess of skin and deep seated infections of lungs, lymph nodes, liver and bones Catalase positive bacteria – Staphylococcus, Kebsiella, Serratia & Burkholderia Fungal infections – Aspergillus (historically leading fatal cause of death) Inflammatory bowel disease

Answer 3

``` Neutrophil assay Dihydrorhodamine test (DHR): flow cytometry test showing abnormal NADPH oxidase activity (inability to metabolize dihydrorhodamine to fluorescent product, rhodamine → decreased green fluorescence) [21] ``` Nitroblue tetrazolium dye reduction test: negative, i.e., incubated leukocytes fail to turn blue when exposed to nitroblue tetrazolium Hypergammaglobulinemia Anemia Genotyping is confirmatory Culture for bacteria and fungi Evidence of gut inflammation Evidence of obstruction e.g. urethra secondary to granuloma Total numbers of neutrophils are normal on FBC ``` Treatment Prophylactic antibiotics Prophylactic anti-fungals Interferon Gamma Bone marrow transplantation ? Gene therapy ```

Answer 4

Severe congenital, cyclic or x-linked Septicaemia, bacterial respiratory infections, soft tissue infections, gingivstomatitis, periodontitis and oral, vaginal and rectal ulcerations Severity parallels the deficiency Diagnosis Neutrophil count on FBC Persistent or cyclical drop every 21 days

Answer 5

``` Function to control infection through Cytotoxicity Cytokine production Co-stimulation of other cells NK cell deficiencies may be found in association with other immunological conditions e.g. XLP (x-linked lymphoproliferative disorder), Wiskott-Aldrich syndrome, and NF-kB essential modulator (NEMO deficiency) Can be secondary Meds, malignancy or infection ``` Primary causes Reduced numbers / absent GATA2 ( a haematopoietic transcription factor) deficiency Reduced function / normal number Can again be secondary (meds, malignancy, infection) Key features Herpes virus infection – VZV, CMV, EBV and HSV Unusual features of HPV – excess malignancy

Answer 6

Autosomal recessive Increased susceptibility to mycobacterial disease Patient with IL-12 deficiency also develop susceptibility to salmonellosis Diagnosis Measurement of cytokine levels (specialist tests) IFN- gamma levels low in IL-12 deficiency Raised in IFN-gamma receptor deficiency Treatment antimycobacterial regimens, prophylaxis, IFN-gamma, HSCT

Answer 7

TLRs = pattern recognition receptors for lots of molecules (self and non-self) that contain danger signals. Key initiators of innate immune response Some defects affect a number of TLRs by impairing signalling pathways downstream of the TLR E.g. IRAK-4 and MyD88 – patients susceptible to pyogenic organisms Investigations (specialised) Measure production of cytokines after exposure of PBMC (peripheral blood mononuclear cells) to TLR ligands

Answer 8

Increased susceptibility to infection Increased susceptibility to autoimmunity Hereditary angioedema

Answer 9

Immune system is compromised due to an extrinsic factor | Rather than an intrinsic genetic defect as seen with primary immunodeficiency (PID)

Answer 10

``` Increased susceptibility to infections Unexpected severity Unusual infections Main difference from Primary Immunodeficiency (PID) Age of onset External cause More common than PID ``` ``` Ask Type of infections Duration of symptoms Severity of symptoms and Medication Use Other medical conditions Identify any organisms cultured ```

Answer 11

Four or more infections requiring antibiotics within one year (eg, sinusitis, bronchitis, pneumonia, otitis media, especially with perforation). Two or more serious sinus infections within 1 year Two or more months on antibiotics with little effect Two or more pneumonias within one year Failure of an infant to gain weight or grow normally Recurrent, deep skin or organ abscesses Persistent thrush in mouth or fungal infection on skin Need for intravenous antibiotics to clear infections Two or more deep seated infections including septicemia A family history of primary immunodeficiency.

Answer 12

Likelihood of clinically significant infection depends action of drug treatment duration Underlying disease process Patient co morbidity Concomitant use of other immunosuppresive medications. ``` Monoclonal Antibodies to B cells Monoclonal Antibodies to T cells Anti Cytokine therapy Agents disrupting T cell Costimulation Agents inhibiting leucocyte Movement Monoclonal Antibodies to Complement Proteins Small Molecule Kinase Inhibitors Checkpoint Inhibitors ```

Answer 13

``` Severe Malnutrition Affects 50% of population is some countries Age extremes (young and old) Infections HIV Drugs –most common Immunosuppressives medication Prednisolone Monoclonal Antibodies Anti convulsants ``` ``` Anatomic Abnormality Diseases causing protein loss Nephrotic syndrome Protein losing enteropathy Haematological Malignancies Surgery and trauma Burns Disruption of epithelial barriers Splenectomy Metabolic Disorders Diabetes Uraemia ``` Both the underlying disease and the treatment contribute in different ways to SID CLL Multiple Myeloma Non Hodgkins lymphoma

Answer 14

``` FBC and film Immunoglobulins and Electrophoresis Serum Free Light Chains Specific Antibodies Pneumococcal and Tetanus Lymphocyte subsets Urine protein/creatinine Ratio ``` Treatment Removal of the causative agent Consider Antibiotic prophylaxis In some cases consider replacement immunoglobulin therapy If untreated Infections and end-organ damage e.g bronchiectasis Significant morbidity and mortality.

Answer 15

The Flow Cytometry laboratory uses the flow cytometer to detect different populations of blood cells in the patient samples. The laboratory also provides a host of functional immunological testing as well as panels for haematological malignancies. In some hospitals it helps to assess and prepare samples for bone marrow transplants. A few common tests are mentioned below. If you are interested, we would encourage a visit to the Flow laboratory to see the full range of testing available.

Answer 16

Lymphocyte subsets are a panel of cells counted using a flow cytometer using labelled fluorochromes that emit light at different wavelengths of light. The cells are first separated by their size and granularity as above, Lymphocytes, seen on the plot above, are then separated based on their attachment to specific fluorochromes labelled antibodies that bind to varies clusters of differentiation belonging to each cell population (e.g. CD3 for T cells). Each population is expressed as a percentage of all cells in the sample. A set number of beads are also added which can be expressed as a % of all cells counted. As the number of beads added is known, this is used to count the actual number of each cell population in the sample. **The basic panel includes:** - Numbers of total lymphocytes - T cells (CD3+) - B cells (CD19/20+) - NK cells (CD16/56) - CD4+ (T helper cells) and - CD 8+ (T cytotoxic cells). Lymphopaenia of different patterns is seen in both primary and secondary immunodeficiency (discussed in other resources). It can also be due to losses from gut, kidneys or thoracic duct drainage. Severe combined immunodeficiency for example is almost always seen with low T cells, with or without the involvement of B cell and NK cell lymphopaenia. CD4+ cells can be low with infection, malignancy or due to drugs. Absent B cells may be seen in immunodeficiency such as secondary agammaglobulinaemia. Lymphocytosis can be seen after viral infections or due to leukaemia and lymphoma. It is important to note that lymphocyte subsets are very tricky to interpret in the middle of an acute infection as any high or low counts could be due to ongoing inflammation, rather than the true baseline for the patient.

Answer 17

**Neutrophil Oxidative Burst:** This is a functional test that looks at the neutrophils ability to phagocytose and kill microbes by testing the activity of NADPH oxidase. Defective neutrophil function should be investigated in patients suspected of having Chronic Granulomatous Disease. CGD is characterised by repeated and life-threatening infections caused by bacterial and fungal organisms. It may mimic inflammatory bowel disease and lead to malabsorption and obstruction of the bowel. Abscesses involving the liver, lungs or lymph nodes are often found. The cells are stimulated to activation and then a dye is used to see the “oxidative burst”. If this is abnormal, further tests are then considered to look for the specific cause of the defect. **T cell proliferation Assays** Upon interaction with microbes, T cells rapidly proliferate to propagate the adaptive immune response. Defects in these pathways can cause immunodeficiency. These assays look for defects in T cell proliferation by subjecting cells to various stimuli, mimicking different parts of the activation pathways and then incubating them for 72 hours. The cells are then counted and compared with a normal control to ascertain where in the pathway a defect might be. This assay is used for diagnosis as well as monitoring of patients post bone marrow transplant. **NK Cell Granule Release Assay** Defects in the cellular toxicity of NK cells and cytotoxic T cells are a feature in Haemophagocytic Lymphohistiocytosis (HLH). HLH is a life threatening immune disorder of severe hyper-inflammation caused by uncontrolled proliferation of activated lymphocytes and histiocytes. This assay is used to analyse resting and activated NK cell degranulation, looking for the products of degranulation after artificially stimulating NK cells.

Answer 18

The proteins laboratory offers assays to look at immunoglobulin levels, serum electrophoresis and subsequent immunotyping/immunofixation of any paraproteins found. It also assays serum light chain, complement activity (classical and alternative pathway) and other tests for complement components. A few common tests are mentioned below. If you are interested, we would encourage a visit to the Proteins laboratory to see the full range of testing available

Answer 19

An immunoglobulin panel consists of IgG, IgM and IgA. IgM, produced first, is often the first antibody to be lost in immunodeficiency. Isolated low IgM can be seen in lymphoproliferative diseases. High polyclonal IgM can be seen in liver diseases and other inflammatory conditions. Raised polyclonal IgA can often be seen in the elderly, but can also be raised due to chronic infection and inflammation. Polyclonally raised IgG can be seen in a reactive state as the other two, but very high levels of polyclonal IgG can be seen in Sjogren’s syndrome and HIV. Immunoglobulin levels cannot reveal if the rise is due to monoclonal or polyclonal increase. Therefore it is always advised to interpret these with serum electrophoresis (+/- serum free light chains), which can detect the presence of a paraprotein. In some cases, IgE is also measured. It can be >50,000 (reference range <100) in patients with Hyper IgE syndrome.

Answer 20

An immunoglobulin panel consists of IgG, IgM and IgA. IgM, produced first, is often the first antibody to be lost in immunodeficiency. Isolated low IgM can be seen in lymphoproliferative diseases. High polyclonal IgM can be seen in liver diseases and other inflammatory conditions. Raised polyclonal IgA can often be seen in the elderly, but can also be raised due to chronic infection and inflammation. Polyclonally raised IgG can be seen in a reactive state as the other two, but very high levels of polyclonal IgG can be seen in Sjogren’s syndrome and HIV. Immunoglobulin levels cannot reveal if the rise is due to monoclonal or polyclonal increase. Therefore it is always advised to interpret these with serum electrophoresis (+/- serum free light chains), which can detect the presence of a paraprotein. In some cases, IgE is also measured. It can be >50,000 (reference range <100) in patients with Hyper IgE syndrome. Serum electrophoresis is useful to investigate if there is a paraprotein present ( a marker of plasma cell disorders such as multiple myeloma). ****A paraprotein is the immunoglobulin product of a single cell clone. It will have only one heavy chain type (e.g. IgG, IgM, IgA or IgD) and/or one light chain type (kappa or lambda). On serum electrophoresis it has the same size and charge and so migrates as a “band” that can be quantified. Check table in notion. **Immunofixation** Immunofixation is a process where multiple samples of the patient sample are run on gel electrophoresis, which each sample stained for a particular heavy or light chain. This is useful in typing the paraprotein when found, and also to find small paraproteins that may be hidden under the beta and gamma curves. In the examples below we see some paraproteins: One band in the same location in IgG and lambda regions showing an IgG lambda paraprotein. Serum free light chains if measured in this case may show an increase in lambda chains. Two bands seen in the same location in the IgG and kappa regions, showing two separate IgG kappa paraproteins. Serum free light chains if measured in this case may show an increase in kappa chains. In the resources section below you will find The Newcastle upon Tyne Hospitals NHS Foundation Trust guidelines for the interpretation and management of immunoglobulins and paraproteins in adults.

Answer 21

The complement cascade comprises of over 20 proteases that form part of the innate immune system, which helps to fight invading microbes in many ways. One such way is by formation of the membrane attack complex. Deficiency of complement components can lead to immunodeficiency amongst a number of other issues. This cascade is also tightly regulated, failure of which can lead to disorders of overactive complement (such as C3G glomerulonephropathy and atypical haemolytic uraemic syndrome). These first line assays, measure the activity of the classical and alternate pathways by simulating an “invading organism” in the patient’s sample to activate the complement. Any deficiencies will show as decreased activity when measured by analysers, prompting further investigations into the individual components of the pathway.

Answer 22

Hyperacute Minutes to hours Pre-existing antibody Acute Days to weeks Cellular (T-cell mediated) Humoral (antibody production requiring T and B cell function) Chronic Months to years Complex aetiology

Answer 23

Pre-existing anti-donor antibodies in recipient (previous pregnancy, transfusion, transplantation etc.) Targets are mainly blood group antigens and MHC molecules Now very rare due to advances in screening and cross-matching Upon transplantation: Rapid binding of antibodies to graft antigens Activation of complement Cell lysis, increased leucocyte recruitment / inflammation Endothelial activation, release of pro-thrombotic substances (e.g. Von Willebrand factor) Platelet aggregation, thrombosis, and occlusion of graft microvasculature Rapid extensive thrombosis and graft infarction, usually needing graft removal

Answer 24

Key step is recognition of donor antigens by recipient T cells Donor antigens presented to T cells either on donor antigen presenting cells (APCs) (Direct) or processed and presented by recipient APCs (indirect If APCs are activated they express co-stimulatory molecule (e.g. B7) that bind receptors on T cells (signal 2) T cells become activated, proliferate and differentiate into effector cells CD8 (cytotoxic) T cells infiltrating the graft Recognise foreign MCH class 1 molecules on donor cells Kill the graft cells, causing tissue damage ``` CD4 Th(helper)1 effector cells infiltrating the graft Recognise donor MHC molecules, release proinflammatory cytokines (IFN-γ, TNF) Recruitment of inflammatory neutrophils and macrophages Tissue damage, altered vascular function, ischaemia ``` CD4 Th2 effector cells help B cells, which proliferate and differentiate into plasma cells Donor specific plasma cells produce antibodies targeting donor antigens (donor specific antibodies - DSAs) Circulating DSAs bind to graft endothelial cells, activate complement, endothelial cell damage, microvascular thrombosis in graft

Answer 25

Acute rejection presentation: Acute deterioration in graft function (rise in creatinine and decreased urine output in renal, deranged LFTs in liver, cardiac failure in heart etc.) Pain in region of graft, and graft oedema Screening tests for rejection include serial monitoring of graft function (e.g. U&Es, urinalysis in kidney, LFTs in liver, PFTs in lung, echo in heart etc.) Differential diagnosis includes infection, immunosuppressant toxicity Diagnosis is with biopsy showing characteristics histological findings Serological tests also used to identify donor-specific antibodies

Answer 26

Occurs over 6 months after transplantation, and is the major cause of long-term graft loss Main features Vascular disease within the graft (transplant vasculopathy) Accelerated arteriosclerosis and luminal narrowing of graft vesseld Development of fibrosis within the graft tissue Chronic inflammation targeting the graft vasculature, and non-immune mechanisms are all thought to drive these processes Both cellular and antibody-mediated mechanisms thought to contribute Other proposed factors include calcineurin inhibitor toxicity

Answer 27

ABO Blood Group Compatibility Required for solid organ transplant (preferred but not required for HSCT) Histocompatibility (HLA Matching) Matching of HLA alleles, particularly DLA-DR, HLA-A and HLA-B The matching of DLA-C, HLA-DP and HLA-DQ is preferred but not always required Requirements vary by organ type Cross-matching Physical cross-match: recipient serum mixed with separated donor lymphocytes (B and T cells separately) Cytotoxic reaction indicates preformed antibodies (donor-specific antibodies – DSA) Virtual cross-match: looking at whether relevant anti-HLA antibodies have been detected previously in recipient’s serum Multiplex serological assays looking for anti-HLA antibodies Induction at time of transplant: Combination treatment with: Steroid (IV methylprednisolone) Calcineurin inhibitor (tacrolimus or ciclosporin) Blocks T cell activation (calcineurin pathway of TCR signalling) Antiproliferative agent (e.g. Mycophenolate mofetil – MMF) Other anti-T cell therapies: Basilixumab (anti-IL2 mAb, prevents T cell proliferation) If high risk also T cell depleting induction therapy with ATG (anti-thymocyte globulin) or alemtuzimab (anti-CD52 mAB) Long-term maintenance immunosuppression is required Balance between preventing rejection and adverse effects (including infection and malignancy)

Answer 28

``` Commonly a triple drug regimen with Corticosteroid Calcineurin inhibitor (tacrolimus or ciclosporin) Antiproliferative agent Azathioprine Mycophenolate mofetil (MMF) Sirolimus (rapamycin) ```

Answer 29

Cellular Rejection (T-cell mediated rejection) Treated with increased immunosuppression High dose puled IV methylprednisolone Methylprednisolone 500mg IV daily for 3 doses With or without T cell depleting therapy, depending on severity Anti-thymocyte globulin (ATG) Usually responds well to treatment Acute Antibody-Mediated Rejection Potent immunosuppression and treatment to remove or suppress production of donor specific antibodies (DSAs) Example regimen (adapted from http://edren.org/ren/handbook/transplant-handbook) Methylprednisolone IV 500 mg daily for 3 days Plasma exchange (plasmapheresis) - to directly remove DSAs High dose (immunomodulatory dose) IV immunoglobulin Anti-B cell agents Bortezomib (proteasome inhibitor – depletes plasma cells), or Rituximab (anti-CD20, B cell-depleting agent) Other immunosuppression continues as standard Infection prophylaxis including co-trimoxazole and valganciclovir Responds less well than cellular rejection Chronic Rejection Difficult, no specific treatment Management of complications as appropriate, e.g. Treatment for heart failure in heart transplant Dialysis in renal failure Other organ specific treatments as indicated End-stage chronic rejection may be an indication for re-transplantation if feasible

Answer 30

Similar but opposite to graft rejection (despite the paradox) Graft contains donor T cells, to which the recipient is foreign The graft mounts an immune response against the host (to be expected Associated primarily with allogeneic haematopoietic stem cell transplantation (HSCT) Can also occur in: Solid organ transplantation (e.g. liver, small bowel) Transfusion on non-irradiated blood products (rare severe complication, primarily in immunocompromised individuals) 3 stages Activation of host APCs Damage to host tissue by underlying disease and conditioning treatments causes cytokine release and stimulation of APCs Donor T cell activation Donor T cells recognize alloantigen on both donor and recipient APCs in lymph nodes, become activated, proliferate and differentiate into effector cells Cellular and Inflammatory Effector Stage Activated donor CD8 (cytotoxic) T cells migrate from lymph nodes to affected organs and kill host cells causing tissue damage Release of inflammatory cytokines (e.g , influx of inflammatory cells (e.g. neutrophils) mediating further tissue damage Acute Onset < 100 days after transplant Affects 3 sites skin, liver and gut ``` Chronic Can affect a wide variety of organ sites Most cases evolve from acute GvHD 20% occur de novo 10% occur after acute GvHD has resolved ```

Answer 31

``` Acute Skin Painful or pruritic erythematous macules Confluent erythema, erythroderma Subepidermal bullae, vesicles, desquamation Liver Deranged LFTs Jaundice Gut Abdo pain Diarrhoea GI bleeding Ileus ``` ``` grade skin stage liver stage gut stage function impaired 0 (none) 0 0 0 0 I (mild) 1-2 0 0 0 II (moderate) 1-3 1 1 + III (severe) 2-3 2-3 2-3 ++ IV (life threat) 2-4 2-4 2-4 +++ ``` Diagnosis Clinical evidence of dysfunction of affected organ Symptoms and signs Deranged LFTs Biopsy of skin, liver or gut to confirm

Answer 32

``` Skin Same as acute GvHD Atrophy and erythema of oral mucosa Sclerodermatous skin changes Joint contractures ``` Pulmonary Obstructive lung disease Dyspnoea, wheeze, cough Non-responsive to bronchodilators Neuromuscular Weakness Neuropathic pain Muscle cramps Ocular Sicca syndrome Haemorrhagic conjunctivitis Gut Same as acute GvDH Also strictures and dysmotility Liver Same as acute GvDH Rarely portal HTN, cirrhosis, liver failure

Answer 33

``` Prevention Donor selection (choose good match) Depletion of T cells from donor graft Drugs to suppress donor T cells steroids, ciclosporin, MMF ``` Treatment Depends on severity If mild skin may be only topical steroids Systemic steroids and MMF if more severe Very severe not responsive to high dose steroids - ATG and other T cell targeted therapies – outlook is poor In malignant disease treating mild GvHD must be balanced against potential benefit from graft versus tumour effect

Answer 34

Must be able to react to harmful foreign antigens (pathogens) and altered self (malignancy), but not self antigens This lack of reactivity to self is known as immune tolerance Self-tolerance fundamental property of the normal immune system failure results in immune reactions against self antigens e.g. autoimmunity multiple tolerance mechanisms normally prevent autoimmunity Lymphocytes that recognise self antigens are killed or inactivated Self-tolerance may be induced in immature self-reactive lymphocytes in the generative lymphoid organs (central tolerance) mature lymphocytes in peripheral sites (peripheral tolerance)

Answer 35

T cells precursors are formed in the bone marrow and migrate to the thymus, where the immature cells are called thymocytes During T cell development, thymocytes produce their T cell receptor and undergo a 2 step “education” process, ensuring They are able to interact with self MHC (otherwise would be useless) Self-reactive cells are deleted, to prevent autoimmunity Some of the “self-reactive” cells in the CD4+ lineage survive and are directed to become regulatory T cells (Tregs) Positive selection choosing T cells that can interact with own MHC Negative selection deleting or inactivating T cells that bind strongly to self antigen in association with MHC Autoimmune regulator (AIRE) gene allows expression of peripheral tissue antigens in the thymic medullary epithelial cells used to test the T cells to check if they are self-reactive B cell similar-check notion

Answer 36

Multiple mechanisms prevent any self-reactive T cells in the periphery from reacting to self antigens Ignorance - Immune privileged sites: eye/brain/testes Anergy: TCR engaged without concomitant co-stimulation Suppression: Regulatory T cells (Treg) can suppress effector functions of other immune cells and enforce tolerance Deletion: via apoptosis – Activated T cells upregulate death receptors (FAS) making them susceptible to apoptosis Regulatory T cells can suppress immune responses through multiple mechanisms, including Compete with other T cells for co-stimulatory ligands on APCs (express CTLA-4, binds B7) and IL-2 (express high affinity IL2 receptor, CD25) Downregulate APCs (direct cell-cell interaction and cytokines) Release anti-inflammatory cytokines (IL10, TGF-β) Down-regulating Immune response Appropriate immune regulation requires appropriate downregulation of immune responses, as well as control of initiation Apoptosis (programmed cell death) of immune cells, especially lymphocytes, is essential for this One mechanism of this is through cell surface ”death” receptors (e.g. FAS, expressed on activated T and B cells) FAS on cell surface interacts with FAS-L (expressed on CD8 T cells, NK cells, and a variety of others) triggering activation of caspases, ultimately leading to apoptosis of FAS expressing lymphocyte (Activation-induced cell death, AICD) FASL is also expressed in immune-privileged sites (e.g. cornea, testes), and on some cancer cells, preventing immune responses from T cells

Answer 37

AIRE deficiency Autoimmune polyendocrinopathy, candidiasis and ecto-dermal dysplasia A rare but good example of when central T cell tolerance is impaired Monogenetic, autosomal recessive AIRE (autoimmunity regulator) is involved in expression on non-thymic genes within thymus for antigen presentation to thymocytes Without this, central T cell tolerance is impaired and autoimmunity develops Endocrine: Hypothyroidism, Addison’s, IDDM etc. Candidiasis: Develop anti-IL17 antibodies, which impairs IL17-mediated fungal immunity FOXP3 deficiency(IPEX syndrome) FOXP3 is essential transcription factor for development of T-reg cells Deficiency leads to lack of T-reg cells Severe, complex immune dysregulatory condition Immunodysregulation, Polyendocrinopathy, Enteropathy, X-Linked Presents in early childhood with: Severe eczema Enteropathy / inflammatory bowel disease Type 1 diabetes and other endocrine manifestations (e.g. thyroid) Severe multiple food allergies Other autoimmune conditions inc. cytopenias, autoimmune hepatitis etc. ALPS-Defect in FAS/FASL Autoimmune Lymphoproliferative Syndrome Monogenetic immune dysregulatory disorder, due to deficiency of FAS or FASL. Usually autosomal dominant, can be recessive Presents usually in childhood with: Lymphoproliferation Lymph nodes, splenomegaly Autoimmune disease Autoimmune cytopenias (haemolytic anaemia, thrombocytopenia etc.) Autoimmune hepatitis, glomerulonephritis, optic neuritis, vasculitis etc. Increased risk of lymphoma

Answer 38

Failure of T and B cell tolerance results in activated T & B cells antibodies directed against self-antigens tissue damage & altered physiological function release of more self antigen Autoantigens are almost impossible to clear once initiated, tends to remain active for a very long time Specific causes of most autoimmune diseases are unknown Some genetic risk factors have been identified e.g. certain MHC class I or II molecules, other genes including immune genes e.g. cytokines, immune receptors, complement components but many predisposed individuals will remain healthy Epidemiological studies of genetically identical individuals  strong role of environmental factors in the initiation of autoimmunity Toxins, drugs, viral & bacterial infections Diet (Western diet) Stress Smoking ``` Rheumatoid arthritis Systemic lupus erythematosis (SLE) Granulomatosis with polyangiitis (GPA), and other vasculitides Psoriasis / Psoriatic arthritis Graves’ disease Goodpasture’s Myasthenia gravis Type 1 diabetes Scleroderma Sjogren’s syndrome Pemphigus/pemphigoid Antiphospholipid syndrome Autoimmune haemolytic anaemia, thrombocytopaenia ```

Answer 39

``` Difficult Gell Coombs classification Organ specific or systemic By nature of immune response B cell: antibody mediated T cell: cell mediated ``` ``` Multiple components of the immune system are typically involved, but significance of each varies Myasthenia gravis (type II) autoantibodies against Acetylcholine receptor (AChR) play a main role causing in disease symptoms Type I DM, IBD, psoriasis (type IV) effector T cells are the main destructive agents (directly cytotoxicity & macrophage activation) However, as in the response to pathogens, all aspects of the immune system have a role ``` type II Antibody mediated hypersensitivity Mechanism: IgG/IgM antibody-antigen interaction on the surface of target cells Examples Goodpasture’s disease (antigen: type IV collagen) Myasthenia gravis (antigen: AChR) Graves disease (antigen: TSH receptor) Note: Antibody formed is a TSH receptor activating antibody Type III Immune complex mediated hypersensitivity Mechanism immune complex formation deposition in tissues leading to local or systemic inflammatory reactions complement activation recruitment of inflammatory cells, release of mediators and toxic substances (proteases etc.) ➝ tissue damage Examples systemic lupus erythematosus (nuclear antigens) rheumatoid arthritis (antibody antigen)

Answer 40

Pathogenesis Anti-GBM disease Antibodies formed against the alpha-3 subunit of type IV collagen Affects alveoli and glomerular basement membrane Clinical features generalised: malaise, fatigue, fever, joint aches and pains lung: haemoptysis, chest pain, cough, shortness of breath kidney: haematuria, proteinuria, peripheral oedema, uraemia, hypertension ``` Diagnosis Anti-GBM antibodies in the serum Kidney biopsy demonstrating Crescentic glomerulonephritis Positive immunofluorescence staining (linear deposition of IgG and complement C3) ``` ``` Disease can be life threatening Severe disease may require: Plasmapheresis Corticosteroids Cyclophosphamide Rituximab (anti-CD20) Renal replacement therapy (dialysis) ```

Answer 41

Complex multigenic disease Most disease causing alleles are present in healthy individuals Usually multiple alleles required, plus environmental trigger for disease Genes associated with antigen presentation HLA-DR2 and –DR3: 2-3 fold increase in SLE risk Genes associated with clearance of apoptotic debris / immune complexes Increased SLE risk with severe deficiencies in C2 (10%), C4 (75%) and C1q (90%). Also increased in some polymorphisms in MBL and CRP Genes associated with lymphocyte activation, proliferation and function BLK, LYN, BANK1 (genes involved in B cell signalling), CTLA-4 (negative co-stimulatory receptor on T cells) Others include genes encoding cytokines and chemokines, and genes regulating apoptosis

Answer 42

A distinct set of rare conditions that are caused by a dysregulated innate immune response with resultant activation of the inflammasome and cytokine excess. Also known as Periodic Fever Syndromes Typically present with recurrent febrile episodes and systemic inflammation affecting multiple organs Can only be diagnosed when infective conditions, malignancy, allergic and immunodeficiency conditions have been excluded Manifestations include periodic fevers, neutrophilic rashes or urticaria, serositis, hepatosplenomegaly, lymph-adenopathy, elevated acute phase reactants, neutrophilia, and a long-term risk of secondary amyloidosis. The innate immune response acts with immediacy to danger or pathogen signals: pathogen-associated molecule patterns (PAMPs) and endogenous damage-associated molecular patterns (DAMPs) PAMPs and DAMPs activate intracellular inflammasomes which then produce an cascade of inflammatory cytokines such as IL-1, IL-18, TNF-α, IL-6, IL-17, type 1 interferons (IFN-α and IFN-β) Autoinflammatory syndromes are the result of a disrupted, dysregulated innate immune system causing a pro-inflammatory state, with the final common pathway being activation of the inflammasome, with resultant unopposed cytokine excess

Answer 43

Approximately 30 classified auto-inflammatory syndromes, though all distinct they do share the same key features Recurrent episodes of fever Symptoms of inflammation in systems (abdominal pain, chest pain, arthritis) and raised inflammatory markers during attacks (CRP and raised neutrophils). May be some evidence of chronic inflammation (raised IgG and/or IgA) Risk of developing amyloidosis with uncontrolled chronic inflammation We will cover the 3 most common: Familial Mediterranean Fever (FMF) Cryopyrin Associated Periodic Fever Syndrome (CAPS) TRAPS Pathogenesis The NRP3 inflammasome is a complex of proteins that activates caspase-1, leading to cleavage of inactive pro-IL-1β to active IL-1β The monogenetic auto-inflammatory syndromes Familial Mediterranean Fever (FMF) and Cryopyrin Associated Periodic Fever Syndrome (CAPS) are both caused by dysregulation of the NLRP3 inflammasome

Answer 44

Caused by mutation in the MEFV1 gene affecting the production of the Pyrin protein Autosomal recessive inheritance. Onset <20 years of age Main ethnic distribution: Turks, Arabs, Jews and Armenians Clinical features: Attack duration: typically 1-3 days Distinguishing symptoms: Fever, serositis, peritonitis, pleuritic, monoarthritis and erysipelas like skin lesions Acute attacks: Raised neutrophil counts Significant risk of amyloidosis: Up to 75%

Answer 45

Caused by a gain of function mutation in the NLRP3/CIAS1 gene Autosomal dominant inheritance. Onset typically < 1 year of age Main ethnic distribution: White Europeans The clinical phenotype is a spectrum: from least to most severe Familial Cold Urticaria: non-itchy urticaria, red eyes, fevers and arthralgia within hours of systemic exposure to cold. Symptoms may last days. Muckle Wells Syndrome: As above, but also symptoms of sterile meningitis, notably sensorineural hearing loss. 1in 4 develop amyloidosis. Chronic Infantile Neurological, Cutaneous and Articular Syndrome (CINCA): Continuous inflammation with no symptom free intervals. Untreated causes very early death

Answer 46

FMF: Colchicine Good effect in symptom control Decreases risk of amyloidosis Approx. 10% non responders CAPS: Symptoms all due to uncontrolled IL1b production and therefore can use highly specific and targeted treatments Anakinra: Human IL1-RA Canakinumab: Anti-IL1b

Answer 47

Due to mutation in TNF receptor meaning that it is permanently “switched on” Current hypotheses: Reduced shedding of TNF receptor post triggering – pro-inflammatory state by ongoing stimulation of retained cells surface receptor Misfolded receptors – ligand independent signalling causing cytokine production Autosomal dominant inheritance Formerly known as familial Hibernian fever, owing to a higher frequency in Northern Europeans, but seen in many ethnic groups. The clinical features of TRAPS that distinguish it from other periodic fever syndromes are: Long durations of attacks: prolonged febrile episodes lasting 3-4 weeks Severe migratory muscle pain with overlying skin redness Swelling around the eye (periorbital oedema; often unilateral) Also have significant abdominal pain (often due to adhesions), chest pain and arthralgia during attacks During attacks: high markers of inflammation (CRP), high neutrophil count 25% risk of amyloidosis The clinical features of TRAPS that distinguish it from other periodic fever syndromes are: Long durations of attacks: prolonged febrile episodes lasting 3-4 weeks Severe migratory muscle pain with overlying skin redness Swelling around the eye (periorbital oedema; often unilateral) Also have significant abdominal pain (often due to adhesions), chest pain and arthralgia during attacks During attacks: high markers of inflammation (CRP), high neutrophil count 25% risk of amyloidosis treatment Mild symptoms: NSAIDs Etanercept – decoy soluble TNFa receptor that binds TNFa, therefore reducing the binding of TNF to actual receptors. Reduces the frequency and severity of flares

Answer 48

Complement is part of the innate immune system Is a group of plasma proteins important in the destruction of microorganisms Complement has 3 major effector functions in host defence: The ability to lyse cells The ability to opsonize particles (making them easier for phagocytes to engulf) The ability of the proteins on activation to generate fragments that have potent inflammatory activity 3 main pathways of complement activation: Classical pathway: Triggered by antibodies that are bound to their antigens Alternate pathway: Activated by the presence of pathogen (antibody independent) Lectin pathway: Activated by lectin-type proteins that have already bound to the carbohydrate on pathogens All pathways ultimately lead to the activation and binding of C3. The pathways then proceed together (terminal pathway) producing a membrane attack complex that forms a transmembrane pore in the pathogen causing cell lysis C4b,C3b-Opsonization C3a,c5a-Inflammation C5,C6,C7,C8-MAC

Answer 49

Deficiencies of complement can be inherited or acquired Acquired complement deficiencies are relatively common and may occur as a result of: decreased synthesis - the liver is the most important organ for the synthesis of several complement proteins, and therefore, low complement levels are often seen in persons with advanced liver disease increased protein loss - nephritic syndrome or protein-losing enteropathies increased consumption - often accompanies immune complex disease, vasculitis, or development of autoantibodies against complement proteins The association of acquired complement deficiency and increased risk of associated infection is as discussed for inherited versions

Answer 50

Classical Deficiency of each of the early proteins (C1, C2, C4) of the classical pathway is very strongly associated with the development of systemic autoimmune diseases, notably SLE Deficiencies also associated with an increase risk of infection with encapsulated bacteria - S. pneumoniae, Haemophilus influenzae, and Neisseria meningitidis Alternative Alternative pathway Properdin deficiency Properdin is a regulatory protein of the alternative pathway that stabilizes C3 and C5 convertases causing increasing activity and deficiency leads to rapid decay of the convertases and therefore less efficacy Is inherited in an X-linked fashion Presents as recurrent severe bacterial infections in childhood. Meningitis due to Neisseria meningitides should raise suspicion of properdin deficiency. Lectin Mannan binding lectin (MBL) is the first protein in the lectin pathway Gene is highly polymorphic and many mutations cause decreased expression of the MBL protein Some suggestion of an increased risk of encapsulated bacterial infection in young children (<2 years of age) Very low MBL levels identified in large numbers of entirely asymptomatic individuals – therefore MBL deficiency is insufficient to cause disease in the absence of other host-defence problems

Answer 51

C3 deficiency Typical presentation: Life-threatening recurrent infections staring in early childhood Particularly susceptible to encapsulated organisms (Commonly Strep. Pneumoniae and N. Meningitides) Associated with immune complex diseases Approx. 25% develop renal disease Approx. 25% develop autoimmune disease (most commonly SLE) C3 Regulatory Proteins: Factor H and Factor I Both work together as regulators of C3b in plasma, leading to its inactivation and therefore controlling the complement cascade Mutations in both Factor H or Factor I can lead to development of atypical haemolytic uraemic syndrome which is characterised by haemolytic anaemia, thrombocytopaenia and acute renal failure. Common Pathways Membrane Attack Complex Deficiency of any of the terminal components of the complement cascade results in susceptibility to gram negative bacteria (particularly Neisseria species) CD59 (MAC-inhibitory protein) is present on cell membranes and is critical for neutralising membrane attack proteins when they bind to our own cells Patients with paroxsysmal nocturnal haematuria (PNH) have an acquired mutation in the PIGA gene which prevents CD59 being expressed on cell surfaces, and the affected cells are then easily (and abnormally) lysed by complement PNH is a rare and life threatening condition. PNH typically presents with red discolouration of urine due to haemoglobin and haemosderin from haemolysis, most commonly first thing in morning. Also notable symptoms of anaemia – tiredness, breathlessness – and increased incidence of thrombosis

Answer 52

In patients with a history of recurrent infection with encapsulated bacteria* from a young age – particularly meningitis – need to exclude complement deficiency * S. pneumoniae, Haemophilus influenzae, and Neisseria meningitidis First line investigation is a CH100 and AP100 Radial immunodiffusion assays CH100 shows classical pathway AP100 shows alternative pathway Solid media has animal red blood cells embedded in it Patients serum added Plate incubated at 37oC If normal complement pathway a “clear zone” forms around the well where the patient serum has lysed the foreign red blood cells Lysis in the CH100 assay with no lysis in the AP100 assay indicates a deficiency in the alternate pathway (such as Properdin) Absence of lysis in the CH100 assay with normal lysis in the AP100 indicates a deficiency in the classical pathway (C1, C4, C2). Absence of lysis in both assays indicates deficiency of a terminal component (C3, C5-C9).

Answer 53

For complement deficiencies causing susceptibility to encapsulated bacterial infections prophylactic antibiotics should be given lifelong For conditions causing inappropriate activation of the complement cascades (aHUS, PNH) then Eculizumab is used Eculizumab recombinant humanized monoclonal antibody against the complement protein C5 inhibits terminal complement activation Be aware of the increased susceptibility of meningococcal infection!!

Answer 54

Many autoimmune diseases are known to be associated with presence of detectable autoantibodies These can be detected in patients’ serum There are two main types of autoantibody tests, with many variations of each method Indirect immunofluorescence assays – looking for antibodies in serum binding to tissue fixed on a slide Immunoassays (e.g. ELISA) – looking for antibodies in serum binging to a purified known antigen fixed on a surface

Answer 55

This method uses slides with tissue fixed on them. These are mostly commercially produced and purchased by the lab Different tissue is used for different assays, depending on what autoantibodies are being looked for, e.g. ANA (anti-nuclear antibodies): Hep 2 cells (a human cell line derived from a patient with cervical cancer in 1950s), have a large nucleus allowing easy visualisation of nuclear autoantibodies Anti-endomyseal antibodies (seen in Coeliac disease): Monkey oesophagus Patient serum is incubated on the slide, allowing any antibodies specific for antigens in the tissue to bind to it After incubation, the slide is washed to remove serum and any antibodies not bound to tissue antigens The slide is then incubated with a secondary antibody specific for human antibodies (usually IgG) labelled with fluorescein (FITC) The slide is then washed again, to remove any unbound fluorescein labelled antibody Then viewed under a fluorescence microscope, and fluorescence seen if autoantibody was present in the serum Fluorescence pattern varies depending on the antigen Examples ANCAs ANCAs are anti-neutrophil cytoplasmic antibodies Found mostly in vasculitis (e.g. GPA) Tissue used on slide are fixed human neutrophils Two main patterns c (cytoplasmic) and p (perinuclear) ANCAs The main cANCA antigen is PR3 (proteinase 3) ANA (Anti-nuclear antibodies) Tissues used include Hep2 cells Many different ANA target antigens, associated with different diseases These result in many different patterns Example shown is homogenous ANA Homogenous ANA antigens include dsDNA and histones Disease associations include SLE, juvenile idiopathic arthritis, rarely other connective tissue diseases Revise the pattern

Answer 56

ANA (Anti-nuclear antibodies) Tissues used include Hep2 cells Many different ANA target antigens, associated with different diseases These result in many different patterns Example shown is homogenous ANA Homogenous ANA antigens include dsDNA and histones Disease associations include SLE, juvenile idiopathic arthritis, rarely other connective tissue diseases Examples-ENAs Many immunoassays look for the same autoantibodies as immunofluorescence assays, but the specific target antigen is known Examples include ENAs (extractable nuclear antigens) e.g. Ro (SSA), La (SSB), Sm, RNP, Scl-70, centromere, Jo-1 These are mostly the various individual antigens that collectively can make up ANA Associated with connective tissue diseases, including SLE, Sjögren’s syndrome, polymyositis / dermatomyositis, systemic sclerosis, mixed connective tissue disease Rather than an educated guess at the antigen target from an ANA fluorescence pattern, the antigen is known, and disease associations likely are clearer However, not all ANA antibodies are easily identified with antigen specific methods, so there is still a role for immunofluorescence ANCAs are anti-neutrophil cytoplasmic antibodies detected by IIF cANCA (cytoplasmic) pattern Associations: vasculitis, most strongly with granulomatosis with polyangiitis (GPA), less so with other vasculitides and rarely seen in infection, rheumatoid arthritis Antigen usually proteinase 3, but can occasionally be others pANCA (perinuclear) pattern Associations: Vasculitis, most strongly with microscopic polyangiitis and eosinophilic granulomatosis with polyangiitis (EGPA), less so with CTDs, and inflammatory bowel disease Antigen is usually myeloperoxidase (MPO) Increasingly, immunoassays for anti-MPO and PR3 are used instead of IIF More specific for vasculitides than IIF ANCAs Automated Multiplex Autoantibody test Many labs, including RVI, now use automated multiplex tests for autoantibodies These use different coloured beads each coated with a different antigen After incubation with serum and labelling with a secondary fluorescent antibody, sample is analysed by lasers, each bead being read for colour (antigen) and fluorescence (amount of autoantibody bound) Allows testing for many different autoantibodies at the same time (e.g. a screen of ENAs)

Answer 57

There is no such thing, so what should you do…? Ask the person asking you exactly what tests it is they want If they are asking this, they probably don’t really know what they want Be wary of blindly requesting tests. What will you do with the answers? If investigating connective tissue disease or arthritis, you probably want ANA / ENA (including dsDNA), and if considering rheumatoid arthritis also anti-CCP and rheumatoid factor If investigating deranged LFTs, you probably want anti-smooth muscle (SMA), anti-mitochondrial (AMA), anti-LKM, and IIF ANA (in RVI this is a “liver autoantibodies” panel) If investigating acute renal failure, haemoptysis, possible vasculitis, you probably want anti-MPO and PR3 (or ANCAs) and anti-GBM Many other possibilities exist for different clinical situations. If in doubt ask the lab or your friendly immunologist

Answer 58

An allergic reaction occurs within minutes of exposure to allergens Upon first contact, a patient is sensitised and generates IgE antibodies These antibodies coat mast cells, causing degranulation on subsequent exposure to allergens The main mediator of an allergic reaction is histamine Late phase reactions due to induction of eosinophils and basophils can cause further symptoms a few hours after initial exposure. Gel and Coombs classification Most allergies* Some delayed drug reactions due to Type 4 hypersensitivity Immediate reaction, within minutes usually Mediated by IgE antibodies released from mast cells and basophils Three Phases Sensitization Immediate phase reaction Late Phase Reaction T helper 2 cells, and the newly recruited eosinophils and basophils secrete pro-inflammatory mediators, cytokines and chemokines,leucotrienes in the late phase which can trigger a second reaction.(6 to 12 hours of after initial symptoms) Repeat exposure can lead to ongoing local inflammation seen in allergic rhinitis and allergic asthma(structural damage

Answer 59

``` Foods (commonest in children) nuts (peanut, tree nut) fish, shellfish wheat, soya, sesame, milk Drugs (commonest in older people) Penicillin Cephalosporins anaesthetic agents ``` ``` Venom Wasp Bee Others Latex Contrast media Topical products such as hair dye and salicylates Excipients such as Polyethylene Glycol (PEG) Idiopathic ```

Answer 60

``` Bronchoconstriction Mucous secretion Reduce cardiac contractility Increased vascular permeability Vasoconstriction: reduce blood to tissues Venodilation: reduced blood to heart ```

Answer 61

``` Respiratory shortness of breath, tachypneoa wheeze or stridor chest tightness respiratory arrest Cardiovascular tachycardia/bradycardia, palpitations hypotension/collapse cardiac arrest ``` ``` Gastrointestinal abdominal pain nausea and vomiting Diarrhoea Central nervous system ‘Feeling of impending doom’ headache altered mental status confusion, drowsiness Skin urticaria, angioedema ``` Mild Symptoms Oral symptoms Urticaria Angioedema (including facial angioedema) ``` Moderate Symptoms Abdominal pain Nausea/Vomitting Mild wheeze “Lump” in throat Severe Symptoms or Anaphylaxis Any compromise of airway, breathing or circulation ``` Mild-Oral histamines Moderate-oral histamines and oral corticosteriods Severe-Adrenaline

Answer 62

Rapid Onset Foods 30mins Stings 12mins Iatrogenic 1min Background history of asthma most important predictor of reaction severity Risk factors Study looking at peanut and tree nut anaphylaxis in UK 1992-2004 1094 patients Risk factors identified included: Pharyngeal oedema 3.8x more likely if severe rhinitis present Tree nuts 2.6x more likely to cause severe reactions than peanuts Life threatening bronchospasm 6.8x more likely if severe asthma present and 2.7x more likely with mild asthma Altered conscious level 3.1x more likely in patients with severe eczema

Answer 63

Highly likely when all 3 criteria are met: Sudden onset and rapid progression of symptoms Life-threatening Airway and/or Breathing and/or Circulation problems Skin and/or mucosal changes (urticaria, angioedema) Diagnosis is supported by exposure to a known allergen for the patient What are the signs and symptoms of anaphylaxis? Anaphylaxis = respiratory compromise or B.P. Skin or mucosal changes alone are not a sign of an anaphylactic reaction Skin and mucosal changes can be absent in up to 20% of reactions Some patients can have only a decrease in blood pressure Gastrointestinal symptoms not uncommon vomiting, abdominal pain, incontinence ``` Airway Airways swelling – tongue and throat Difficulty breathing and swallowing Sensation the throat is ‘closing’ Hoarse voice Stridor ``` ``` Breathing Shortness of breath Increased respiratory rate Wheeze Confusion – may be a sign of hypoxia Cyanosis (appears blue) – a late sign Respiratory arrest ``` ``` Circulation Signs of shock- pale, clammy Increased pulse rate(tachycardia) Low blood pressure (hypotension) Decreased conscious level Myocardial ischaemia / angina Cardiac arrest DO NOT STAND PATIENT UP ``` Disability Sense of impending doom Anxiety, panic Decreased conscious level caused by airway, breathing or circulation problem ``` Exposure Look for skin changes Can be first feature Present in >80% of anaphylactic reactions Skin, mucosal or changes of both ``` ``` Triptase Released from activated mast cells Levels stable once collected Levels peak in 1-2hrs and normalizes within 12-14 hrs 1x gold topped (clotted / serum) tube Record time taken on sample & in notes Timing 1-2hrs after start of symptoms (no later than 4 hrs) At > 24hrs (or in convalesence) ```

Answer 64

Resuscitation Council Emergency treatment of anaphylactic reactions Jan 2008 – review due 2021 Nice Guidance published Dec 2011(r/v’d 2016) Anaphylaxis: assessment and referral after emergency treatment ``` BSACI Specific guidelines (e.g. GA, Nuts, penicillin, milk, egg) ```

Answer 65

ABCDE Airway support and oxygenation lay the patient flat with legs up Most important drug in treatment of anaphylaxis Must be given to all patients with life threatening features Hypotension Difficulty breathing / swallowing (airway involvement) Must be given IM May fail to reverse symptoms in patients on beta blockers (may need additional doses) Adrenaline acts fast, directly on the factors that cause the life-threatening symptoms of anaphylaxis1 Timely IM injection of adrenaline is critical to receiving physiological benefits2,3 Role of adrenaline-Acts on alpha and beta adrenal receptors Alpha-Vasoconstriction peripheral resistance low mucosal edema beta-bronchodilation reduce inflammation increase cardiac output Establish airway High flow oxygen Iv fluid challenge Then consider iv chlorphenamine & hydrocortisone – do not delay adrenaline administration to given these.

Answer 66

Risk of recurrence of symptoms Caution in asthmatics Those with continuing absorption of allergen Prior history of biphasic reactions (1-20%) NICE guidelines recommend 6-12 hours from onset of symptoms depending on response to emergency treatment Consider 3 day course antihistamine (cetirizine) If known allergy patient and adrenaline autoinjector has been used, it should be replaced prior to leaving Consider prescribing adrenaline autoinjector if triggers unknown / difficult to avoid If new patient or if update on diagnosis / self management plan - Refer to allergy clinic Adrenaline auto injectors Indicated for anaphylactic reactions to an unavoidable substance Caution in patients with cardiovascular disease Beta Blockers Patients need to carry 2 pens Training required Indications for use Practical aspects of administration

Answer 67

``` Types of Allergy IgE mediated allergy Acute onset, Immediate Release of histamine via IgE mechanisms Urticaria, angioedema Non IgE mediated allergy Delayed onset, T cell mediated Release of histamine via non IgE mechanism Dysmotility, Eosinophilic Oesophagitis, FPIES Systemic allergy Immediate - Anaphylaxis Delayed - Food protein Induced Enterocolitis (FPIES) ``` Clincal features Skin IgE mediated- Angioedema of the lips, tongue and palate non IgE mediated-Atopic suppurative eczema GI IgE mediated-Faltering growth, oral puritius,abdo pain, vomiting diarrhoea non IgE mediated-Faltering growth,GORD,perianal disease,constipation Respiratory IgE mediated-URTI,nasal itching, sneezing,rhinorrhea non IgE mediated- persistent wheeze Diagnostic tests ``` IgE mediated disease - Helpful Skin prick tests Specific IgE blood test (Immunocap) Component resolved diagnostics Non IgE disease - Unhelpful Eosinophils / basophils /mast cells Biopsies of the gut Nutrition growth centiles malnutrition ```

Answer 68

``` An exaggerated propensity in genetically predisposed individuals to produce IgE and Non IgE responses to common environmental triggers. The IgE mediated Allergic March Types of allergic co-morbidities Atopic Dermatitis (Eczema) Food allergy Allergic Rhinitis Atopic Asthma Drug Allergy ```

Answer 69

``` Food Allergy Management plan State the culprit trigger Name, address, telephone numbers Outline how to treat mild, moderate and severe symptoms Prescribe a ‘Rescue Medication Pack’ Antihistamine (eg cetirizine) Bronchodilator (eg Salbutamol) Adrenaline Auto-injector - Risks ```

Answer 70

Presentations in different circumstances or ethnic groups Atopic dermatitis Genetic predisposition – filaggrin mutation Increased sensitisation across leaky skin High risk for food allergy Discoid eczema Discoid Not related to food allergy Eczema and infection Eczema Herpeticum Staph Aureus / streptococcus I ``` Faltering growth - refer to dietitian Faltering growth Symmetrical IgE and Non IgE food allergy Eczema- high risk Vitamin D Deficiency Northern counties Eczema – barrier treatments Rickets Non IgE mediated cow’s milk allergy Calcium supplements ```

Answer 71

``` urticaria superficial swelling of the skin (epidermis and mucous membranes) that results in a red, raised, itchy rash angioedema a deeper swelling within in the dermis and submucosal or subcutaneous tissues acute symptoms < 6 weeks chronic symptoms > 6 weeks on a nearly daily basis ``` Urticaria A central swelling of variable size, surrounded by erythema (wheal) Itchy, burning sensation Fleeting, usually returning to normal within 30mins – 24 hours Histamine Angioedema Skin coloured swelling of the dermis and deeper subcutaneous tissue Painful swelling, no itch Slower resolution compared to wheals, can last up to 72 hours Bradykinin

Answer 72

``` Chronic spontaneous urticaria (CSU) spontaneous appearance of wheals/angioedema or both for > 6 weeks due to unknown causes Inducible urticaria cold urticaria delayed pressure urticaria solar urticaria vibratory urticaria cholinergic urticaria contact urticaria aquagenic urticaria ``` Triggers ``` idiopathic (i.e. CSU) stress infection medications NSAIDs, opiates ACEi (angioedema only) environmental hot, cold, pressure minor trauma (dermographism) exercise vibration heat hot bath, sun thyroid dysfunction electrolyte abnormalities Vit B12, folate, ferritin, VitD H.pylori infection urticarial vasculitis ```

Answer 73

diagnosis of urticaria is based primarily on the clinical history and appearance of rash blood tests FBC, UECs, LFTs, TFTs, Vit B12, Folate, Ferritin, Vit D C4, C1 inhibitor (for angioedema) ANA, TPO/TG antibodies (for autoimmunity) provoking tests scratch with wooden spatula (dermographism) ice cube, exercise, pressure, water Allergy testing patients often referred to hospital in the belief that CSU is caused by food allergy expect skin prick testing (SPT) food is not a cause of CSU, so therefore SPT is rarely indicated in some patients, the sight of negative SPTs can be reassuring that allergy is not the cause of their symptoms ``` Prognosis acute urticaria excellent normally self-limiting & short-lived responds well to standard treatment chronic urticaria often relapsing and remitting spontaneous resolution in 60% of patients within 1 year and 80% of patients by 5 years 20% of patients remain symptomatic 10 years after first presentation ```

Answer 74

avoidance strategies heat, stress, exercise, medications discontinue ACE inhibitor (causes angioedema only) ``` 2nd generation antihistamines Cetirizine, Loratadine, Fexofenadine less sedation than 1st gen (e.g. chlorphenamine) start with daily dose titrate to high dose Cetirizine/Loratadine 20mg bd Fexofenadine 360mg bd ``` short course of corticosteroids if symptoms very severe e.g. Prednisolone 20mg daily for 3-5 days leukotriene antagonists Montelukast 10mg nocte may be useful if concurrent reactivity to aspirin, NSAIDs, pressure or autoimmune based urticaria Tranexamic acid for angioedema only immunosuppression Cyclosporine inhibits mast cell and basophil degranulation requires monitoring: blood pressure, FBC, UECs, urinalysis S/E: headache, nausea, tremor, renal impairment anti-IgE therapy Omalizumab

Answer 75

monoclonal antibody against IgE used in the treatment of CSU and severe asthma add‑on therapy for severe CSU in adults and children >12 years if: evidence of disease severity, e.g. UAS7 score ≥28 failed maximal medical therapy, i.e. antihistamines + leukotriene receptor antagonists 300mg subcutaneous monthly injection 2 x 150mg pre-filled syringes side effects injection site reactions sinusitis, headache, arthralgia, transient worsening of urticaria NICE recommendations standard course is 6 months, must be discontinued to assess if there is spontaneous remission can be restarted if urticaria relapses if no improvement after the 4th dose, treatment should be reviewed (?needs to be discontinued) Omalizumab is administered under the supervision of immunology/allergy or dermatology cost 150mg syringe: £256.15 single dose of 300 mg: £512.30 24‑week course of treatment: £3073.80 Omalizumab home therapy patients are able to administer their own treatment at home receive 2-3 training sessions in hospital (follow SOP) if ok, remainder of injections at home pros more convenient/flexible, minimise travel to hospital cons requires manual dexterity (or family member/friend), storage of medication, monitoring more difficult, management of side effects ``` If Omalizumab doesn't work? ?wrong diagnosis consider other immunosuppressants cyclosporine mycophenolate methotrexate combination (e.g. Omalizumab + immunosuppressant) ```

Answer 76

validated tool: Urticaria Activity Score (UAS7) patient records severity of itching and number of wheals daily for 7 days score <7: good control of disease score ≥28: severe disease

Answer 77

Incidence 1:50 000-1:150 000 Autosomal dominant Defect in SERPING1 gene No ethnic or sexual predilection ``` Disorder of C1 inhibitor (C1INH) Type I (85%) Low levels of C1INH Type II (15%) Normal level but functional defect ``` ``` Clinical Presentation: Repeated episodes of oedema: Face Extremities Genitals Intestines Larynx ``` Combination and migratory attacks common Increases over 36 hours Attack site and severity variable – within same person and family members No Urticaria Often a delay in diagnosis > 7 years Many patients have had emergency abdominal surgery pre-diagnosis Diagnosis made earlier if family history Families may accept these attacks as normal for their family Exacerbated by oestrogens and ACE-inhibitors – must be avoided

Answer 78

Recognised triggers: OCP (oestrogen – containing) Trauma Infection Stress Dental surgery (trigger for laryngeal attack) / medical interventions Exacerbated by oestrogens and ACE-inhibitors – must be avoided

Answer 79

Labs: 1) C1INH - low levels, or low function C1 esterase inhibitor 2) Low levels of C4(Also function) If C4 normal not likely to be due to be HAE

Answer 80

Laryngeal oedema: Prudent use ETT intubation Monitored setting until resolution of attack Steroids/antihistamines NOT useful Nebulised adrenaline / adrenaline may decrease the vascular component of oedema but doesn’t change the underlying process Specific treatment C1 inhibitor or Bradykinin inhibitor Intestinal oedema: Aggressive replacement fluid losses (vomiting and diarrhoea) Pain management Non-sedating anti-emetics Avoid interventional procedures unless unusual symptoms (hematemesis, PR bleeding) ``` Established Pharmacologic Treatments: Prophylaxis: 1) Androgen derivatives 2) Antifibrinolytic agents 3) New therapies ``` Acute attacks: 1) C1INH concentrate 2) Icatibant Acute treatment C1 Inhibitor concentrate - plasma derived Usually 1000 – 2000 units per intravenous infusion (target 20u/kg) Safe and effective – no long term side effects reported although is a blood product Excellent and prompt response in most patients Some may need second dose C1 inhibitor concentrate – recombinant 50IU / kg Made from rabbit milk – caution if rabbit allergy ``` Bradykinin inhibitors For acute treatment only Icatibant 30mg in 3 mls – selective agonist of bradykinin receptors Slow subcutaneous injection Frequently self administered ``` Kallikrein inhibitors Available in America Prophylactic therapies ``` Antifibrolyntics Danazol (androgenic steroid) Significant Angioedema at least twice weekly over period of 2 months-C1 inhibitor twice weekly or pre- intervention e.g. dental treatment/ endoscopy Lanadelumab Antibody directed at kallikrein Subcutaneous injection every 2-4 weeks 87% reduction in attack rate NICE guidance – must have 2 attacks per week ```

Answer 81

Acquired deficiency of C1 Esterase Probably due to production of interfering antibodies Most commonly B-cell lymphoproliferative disorders (esp. lymphoma) but also in autoimmune disease (e.g. SLE) More common after 4th decade Very rare ``` Clinical presentation: No family history (distinguish from HAE) Non-pruritic Non-pitting Again NOT associated with urticaria Consider underlying diagnosis ```

Answer 82

Investigations Low C1-INH levels Low C1q levels Low C4 levels Low C2 levels Autoantibodies (look for autoimmune disease) Immunoglobulins and electrophoresis (? Paraprotein) CT chest, abdo, pelvis - ? Evidence of lymphadenopathy / splenomegaly ``` Management of acquired angioedema: Supportive (airway) Androgens Antifibrinolytics C1 Inhibitor concentrate (may need more) Icatibant Less data for newer therapies / those in development Immunosuppressive therapy ```

Answer 83

Other causes of angioedema Allergic – often with hives, responds to antihistamines Drug induced – often ACE inhibitors Idiopathic / spontaneous ``` ACE induced angioedema Life-threatening to minor swelling (may not report to health-care provider) Can resolve spontaneously Often unilateral Often starts overnight ``` In severe cases: Swelling of lips, tongue, post pharynx, eyes Dyspnea, dysphagia, dysphonia in up to 20% patients  may cause airway obstruction Idiopathic angioedema Recurrent angioedema, no recognized exogenous precipitant, not associated with concomitant urticaria Typically: episodes of swelling of lips, cheeks, eyes, tongue, pharynx, extremities, genitalia Slower than allergy induced May be worsened by infection Try antihistamines, steroids acutely Antihistamines & antifibrinolytics

Answer 84

< 6 months 150 micrograms (0.15ml 1 in 1,000) 6 months - 6 years 150 micrograms (0.15ml 1 in 1,000) 6-12 years 300 micrograms (0.3ml 1 in 1,000) Adult and child > 12 years 500 micrograms (0.5ml 1 in 1,000) In the treatment of anaphylaxis, you can repeat adrenaline every 5 minutes Given intramuscularly usually to the anterolateral aspect of the middle third of the thigh

Answer 85

Skin prick test Most commonly used test as easy to perform and inexpensive. Drops of diluted allergen are placed on the skin after which the skin is pierced using a needle. A large number of allergens can be tested in one session. Normally includes a histamine (positive) and sterile water (negative) control. A wheal will typically develop if a patient has an allergy. Can be interpreted after 15 minutes Useful for food allergies and also pollen Radioallergosorbent test (RAST) Determines the amount of IgE that reacts specifically with suspected or known allergens, for example IgE to egg protein. Results are given in grades from 0 (negative) to 6 (strongly positive) Useful for food allergies, inhaled allergens (e.g. Pollen) and wasp/bee venom Blood tests may be used when skin prick tests are not suitable, for example if there is extensive eczema or if the patient is taking antihistamines Skin patch testing Skin patch testing Useful for contact dermatitis. Around 30-40 allergens are placed on the back. Irritants may also be tested for. The patches are removed 48 hours later with the results being read by a dermatologist after a further 48 hours

Answer 86

500 microgram Adrenaline,200mg hydrocortisone and 10mg chlorphenamine are medications used in anaphylaxis

Immunology Flashcards

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