Immunology Part 1 (p102-123- immunodeficiencies, hypersensitivity, modulation) Flashcards

1
Q

What is reticular dysgenesis?

A

Failure of stem cells to differentiate along myeloid or lymphoid lineage- failed production of neutrophils, lymphocytes, monocytes/macrophages, platelets.
Fatal in early life unless corrected with transplantation

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2
Q

What is Kostmann syndrome?

A

Specific failure of neutrophil maturation- autosomal recessive severe congenital neutropenia

Classic form due to mutation in HCLS-1 associated protein X-1 (HAX1)

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3
Q

What is cyclic neutropenia?

A

Specific failure of neutrophil maturation- autosomal dominant episodic neutropenia every 4-6wks

Mutation in neutrophil elastase

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4
Q

What is leukocyte adhesion deficency?

A

Neutrophils lack adhesion molecules CD11a/CD18 and CD11b/CD18, which normally bind to ligands on endothelial cells and regulate neutrophil adhesion and transmigration so they fail to exit blood stream

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5
Q

What is leukocyte adhesion deficiency characterised by?

A

High neutrophil count in blood
Absence of pus formation
Delayed umbilical cord separation

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6
Q

What happens in chronic granulomatous disease?

A

Absent respiratory burst- deficiency of one of the components of NADPH oxidase and subsequent inability to generate oxygen free radicals that kill intracellular microorganisms

Excessive inflammation- persistent neutrophil and macrophage accumulation so inability to degrade antigens

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7
Q

Which bacteria are people with chronic granulomatous disease particularly susceptible to?

A
Catalase positive- PLACESS:
Pseudomonas
Listeria
Aspergillus
Candida
E.Coli
Staph aureus
Serratia
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8
Q

What result would you see for the nitro-blue tetrazolium (NBT) test in a chronic granulomatous patient and why?

A

Negative- NBT is a dye that changes colour from yellow to blue following interaction with hydrogen peroxide

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9
Q

How does SCID present generally?

A
Unwell by 3months of age (protected beforehand by IgG from mother across placenta then colostrum) with:
Failure to thrive
Persistent diarrhoea
Skin disease
Graft versus host disease
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10
Q

What mutation is involved in X-linked SCID?

A

45% of SCID
Mutation of gamma chain of IL2 receptor on chromosome Xq13.1 -> inability to respond to cytokines causes early arrest of T cell and NK cell development and immature B cell production

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11
Q

What causes DiGeorge syndrome and what does it feature?

A
Deletion at 22q11.2
CATCH 22:
Cardiac abnormality (ToF)
Abnormal facies- high forehead and low ears
Thymic aplasia- T cell lymphopenia
Cleft palate
Hypocalcaemia/hypoparathyroidism
22- chromosome
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12
Q

How are phagocyte deficiencies diagnosed?

A

NBT or DHR flow cytometry test

NBT changes from yellow to blue following interaction with hydrogen peroxide
DHR is oxidised to rhodamine which is strongly fluorescent following interaction with hydrogen peroxide

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13
Q

How do you treat phagocyte deficiencies?

A

Aggressive management of infection
Abx prophylaxis
BMT- definitive

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14
Q

What is treatment for chronic granulomatous disease?

A

IFN-gamma

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15
Q

What different types of complement deficiency are there?

A

C1q deficiency
Factor B deficiency
C9 deficiency
SLE

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16
Q

What are the consequences of complement deficiencies?

A

Increased susceptibility to encapsulated bacterial infections

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17
Q

How are complement deficiencies diagnosed?

A

CH50 and AP50 tests

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18
Q

How do you treat complement deficiencies?

A

Vaccination, prophylactic Abx, high levels of suspicion + early treatment, screen family members

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19
Q

What do T cell deficiencies increase the likelihood of?

A
Viral infections (CMV)
Fungal infection (pneumocystitis or cryptosporidium
Bacterial infections- esp intracellular organisms (TB, salmonella)
Early malignancy
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20
Q

What do antibody deficiencies increase the risk of?

A

Bacterial infections- staph or strep
Toxins (tetanus, diptheria)
Some viral infections (enterovirus)

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21
Q

How are lymphocyte deficiencies diagnosed?

A

WCC, lymphocyte subsets, serum Ig and electrophoresis, functional tests

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22
Q

How are T cell deficiencies managed?

A

Infection prophylaxis and treatment, Ig replacement, BMT gene therapy, thymic transplantation in digeorge syndrome

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23
Q

How are B cell deficiencies managed?

A

Aggressive tx of infection, Ig replacement every 3 weeks, BMT, immunisation in IgA deficiency

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24
Q

What is a type 1 hypersensitivity disorder, what is it mediated by and what are typical symptoms?

A

Immediate reaction provoked by re-exposure to an allergen. IgE mediated- mast cells release mediators resulting in vasodilators, increased permeability and smooth muscle spasm

Symptoms:
Angioedema, urticaria, rhinoconjunctivitis, wheeze, d+v, ANAPHYLAXISo

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25
Q

How do you treat atopic dermatitis?

A
Emollients
Skin oils
Topical steroids
Antibiotics
PUVA phototherapy
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26
Q

How do you treat a food allergy?

A

Dietician
Food avoidance
Epipen

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27
Q

How are most allergies diagnosed?

A

Skin prick test

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28
Q

What is anaphylaxis?

A

A severe systemic allergic reaction- respiratory difficulty and hypotension

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29
Q

How do you manage anaphylaxis?

A

Raise legs, 100% oxygen, IM adrenaline 500mcg, inhaled bronchodilators, hydrocortisone 100mg IV, chlorphenamine 10mg IV, IV fluids

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30
Q

What does a negative skin prick test exclude?

A

IgE mediated allergy

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31
Q

What is a radioallergosorbent test (RAST) used for?

A

Measure levels of IgE in serum against a particular allergen (peanut)- confirms dx and monitors response to anti-IgE treatment
Indications- when they can’t stop anti-histamines, anaphylaxis hx or severe eczema

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32
Q

What are component-resolved diagnostics?

A

It measures IgE response to a specific allergen protein e.g. peanuts contain at least 5 major allergens so it can specifically measure one of them

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33
Q

What is the gold standard for assessing food allergy?

A

Double blind oral food challenge but risk of severe reaction

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34
Q

What is a useful measure of mast cell activation during an acute allergic episode?

A

Mast cell tryptase

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35
Q

What is a type II hypersensitivity disorder?

A

IgG or IgM antibody reacts with cell or matrix associated self antigen. Results in tissue damage, receptor blockade/activation

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36
Q

Name as many type II hypersensitivity disorders as possible (13)

A
Haemolytic disease of Newborn
Autoimmune haemolytic anaemia
Autoimmune thrombocytopenic purpura
Goodpasture's syndrome
Pemphigus vulgaris
Graves disease
Myasthenia Gravis
Acute Rheumatic fever
Pernicious anaemia
Churg-strauss syndrome
Wegener's granulomatosis
Microscopic polyangiitis
Chronic urticaria
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37
Q

What is the pathology of HDN?

A

Maternal IgG attack antigens on neonatal erythrocytes

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38
Q

How is HDN treated?

A

Maternal plasma exchange or exchange transfusion

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39
Q

How do you treat autoimmune haemolytic anaemia?

A

Steroids

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40
Q

What antigen is involved in autoimmune thrombocytopenic purpura?

A

Glycoprotein IIb/IIIa on platelets

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41
Q

How is autoimmune thrombocytopenic purpura diagnosed?

A

Anti-platelet antibody

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42
Q

How is autoimmune thrombocytopenic purpura treated?

A

Steroids, IVIG, Anti-D antibody, splenectomy

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43
Q

What antigen is involved in Goodpasture’s syndrome?

A

Non collagenous domain of basement membrane collagen type IV

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44
Q

How is Goodpasture’s syndrome diagnosed?

A

Anti-GBM Ab

Linear smooth IF staining of IgG deposits on BM

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45
Q

How is Goodpasture’s syndrome treated?

A

Corticosteroids and immunosupression

46
Q

What antigen is involved in Pemphigus vulgaris?

A

Epidermal cadherin

47
Q

How is pemphigus vulgaris diagnosed?

A

Direct immunofluorescence showing IgG deposition

48
Q

How is Graves disease diagnosed?

A

Anti-TSH R Ab

49
Q

How do you treat Graves disease?

A

Carbimazole and propylthiouracil

50
Q

What antigen is involved in Myaesthenia Gravis?

A

Acetylcholine receptor

51
Q

How is myaesthenia gravis diagnosed?

A

Anti Ach-R Ab and abnormal EMG tensilon test

52
Q

How do you treat myaesthenia gravis?

A

Neostigmine

Pyridostigmine

53
Q

What antigen is involved in acute rheumatic fever?

A

M proteins on group A strep

54
Q

How do you treat acute rheumatic fever?

A

Aspirin, steroids and penicillin

55
Q

What commonly occur in acute rheumatic fever?

A

Myocarditis
Arthritis
Sydenham’s chorea

56
Q

What antigen is involved in pernicious anaemia?

A

Intrinsic factor and gastric parietal cells

57
Q

How do you diagnose pernicious anaemia?

A

Anti-gastric parietal cell Ab, Anti-IF Ab, Schilling test

58
Q

Treatment for pernicious anaemia?

A

Dietary B12 or IM

59
Q

How is Churg-Strauss syndrome (eGPA) diagnosed?

A

p-ANCA, granulomas, eosinophil granulocytes

60
Q

How is Churg-Strauss treated?

A

Prednisolone
Azathioprine
Cyclophosphamide

61
Q

How is Wegener’s granulomatosis (GPA) diagnosed?

A

c-ANCA

62
Q

How is Wegener’s treated?

A

Corticosteroids
Cyclophosphamide
Co-trimoxazole

63
Q

How do you diagnose chronic urticaria due to meds, cold, food, insect bites etc?

A

Challenge test, ESR (raised in urticarial vasculitis) + skin prick test

64
Q

What is a type III hypersensitivity disorder?

A

IgG or IgM immune complex (Ab vs soluble Ag) mediated tissue damage

65
Q

Name some example type III hypersensitivity disorders?

A

Mixed essential cryoglobulinaemia
Serum sickness
Polyarteritis nodosa (PAN)
Systemic lupus erythematosus (SLE)

66
Q

What antigen is involved in serum sickness?

A

Proteins in antiserum (Penicillin)

67
Q

How is serum sickness diagnosed?

A

Decreased C3

Blood shows immune complexes or signs of blood vessel inflammation

68
Q

How do you treat serum sickness?

A

Discontinue precipitant, steroids, anti-histamines

69
Q

What antigens are involved in polyarteritis nodosa?

A

Hep B and Hep C antigens

70
Q

How is PAN diagnosed?

A

Clinical criteria, biopsy and ‘rosary sign’

71
Q

What is a type IV hypersensitivity disorder?

A

Delayed hypersensitivity. T-cell mediated

72
Q

Name some examples of type IV hypersensitivity disorders?

A
T1DM
MS
Rheumatoid arthritis
Contact dermatitis
Mantoux test
Crohn's
73
Q

What antigen is involved in T1DM?

A

Pancreatic beta cell proteins (glutamate decarboxylase)

74
Q

What antigen is involved in MS?

A

Oligodendrocyte proteins (myelin basic protein, proteolipid protein)

75
Q

Diagnosis of MS?

A

CSF shows oligoclonal bands of IgG on electrophoresis

76
Q

How do you treat MS?

A

Corticosteroids

Interferon-beta

77
Q

Where is the antigen involved in rheumatoid arthritis?

A

Synovial membrane

78
Q

How do you diagnose rheumatoid arthritis?

A

X-ray
Rheumatoid factor (85% sensitive)
Anti-CCP (95% specific)
Raised ESR and CRP

79
Q

How do you treat rheumatoid arthritis?

A

Analgesia
Steroids
DMARDs

80
Q

How do you treat crohn’s?

A

Antibiotics

Anti-inflammatory drugs e.g. mesalazine, TNF alpha antagonists e.g. infliximab or steroids

81
Q

What is limited cutaneous scleroderma?

A

CREST syndrome:

Calcinosis, Raynaud’s, esophageal dysmotility, sclerodactyly, telangiectasia

82
Q

How is limited cutaneous scleroderma (CREST) diagnosed?

A

Anti-centromere antibodies

83
Q

What is difference between limited and diffuse cutaneous scleroderma?

A

Limited- CREST
Diffuse- CREST + GIT + interstitial pulmonary disease + renal problems
Antibodies- anti-topoisomerase, RNA pol I, II, III, fibrillarin

84
Q

What symptoms are there in Sjogren’s syndrome?

A

Dry mouth, eyes, nose and skin

May affect kidneys, vessels, lungs, liver, pancreas and PNS

85
Q

What antibodies are present in Sjogren’s?

A

Anti-Ro and anti-La

86
Q

What is IPEX syndrome?

A

Immune dysregulation, polyendocrinopathy, enteropathy and X-linked inheritance syndrome
Most affected children die within 2y- BMT only cure

87
Q

Which HLA serotypes are associated with coeliac disease?

A

DQ2 or DQ8

28 or not to eat, that is the question

88
Q

Gold standard for coeliac diagnosis?

A

Duodenal biopsy (not 1st line)

89
Q

What does Human Normal Immunoglobulin (antibody replacement) treatment consist of and what is it used for?

A

Preformed IgG from donors against full range of organisms given every 3-4w

Used for:
Primary antibody deficiencies (CVID, Brutons etc)
Secondary deficiencies (CLL and multiple myeloma post BMT)
90
Q

What is specific immunoglobulin (passive vaccination) treatment used for?

A

Post-exposure prophylaxis with Ig specific to rabies, varicella zoster, Hep B and tetanus

Derived from plasma donors with high IgG titres of specific Ab

91
Q

What is the aim and what involves the use of interferons (recombinant cytokines)?

A

Boost immune response to cancer and some pathogens e.g:
Interferon alpha used for Hep C, Hep B, Kaposi’s, hairy cell leukaemia, MM
Interferon beta used for relapsing MS, Bechets
Interferon gamma- chronic granulomatous disease

92
Q

How do iplimumab and pembrolizumab/nivolumab work?

A

They block immune checkpoints

Iplimumab is an antibody specific for CTLA4 so blocks downregulatory immune checkpoint and allows T cell activation- used in advanced melanoma

Pembrolizumab/nivolumab are an antibody specific for PD-1 which works in same way as iplimumab

93
Q

What types of immunosuppresive therapy are there?

A
Anti T cell monoclonal antibodies
Anti proliferative agents
Inhibitors of cell signalling
Corticosteroids
Anti TNFa monoclonal antibodies
Plasmapheresis
94
Q

How do corticosteroids suppress the immune system?

A

They inhibit phospholipid A2 which blocks arachidonic acid, reduces prostaglandin synthesis, inhibits phagocyte trafficking and release of proteolytic enzymes, lymphopenia, promotes apoptosis, blocks cytokine gene expression and decreased Ab production

95
Q

When are corticosteroids used to suppress the immune system?

A

Auto-immune disease, auto-inflammatory disease, prevention and treatment of transplant rejection

96
Q

Name some examples of anti-proliferative agents

A

Cyclophosphamide
Mycophenolate mofetil
Azathioprine
Methotrexate

97
Q

How does cyclophosphamide suppress the immune system?

A

Alkylates the guanine base of DNA and damages it, preventing cell replication. Affects B cells > T cells

98
Q

When are cyclophosphamides used?

A

CTD, vasculitis, anti-cancer agent

99
Q

How does mycophenolate mofetil work?

A

Inhibits IM PDH, prevents guanine synthesis so blocks de novo nucleotide synthesis and prevents replication of DNA

100
Q

When is mycophenolate mofetil and azathioprine used?

A

Transplantation, auto-immune diseases and vasculitis

101
Q

How does azathioprine work?

A

Anti-metabolite agent. Metabolised by liver to 6-mercaptopurine, blocks de novo purine synthesis- prevents DNA replication, preferentially inhibits T cell activation and proliferation

102
Q

How does methotrexate work?

A

Inhibits dihydrofolate reductase (DHFR) therefore decreases DNA synthesis

103
Q

When is methotrexate used?

A

RA, psoriasis, crohn’s, chemo and abortifacient

104
Q

How does plasmapheresis work?

A

Plasma is treated to remove immunoglobulins and then reinfused

105
Q

When is plasmapheresis used?

A

Severe antibody-mediated disease (Goodpastures, MG, vascular rejection)

106
Q

Name some examples of cell signal inhibitors?

A
Tacrolimus
Cyclosporin
Sirolimus
Tofacitinib
Apremilast
107
Q

How do tacrolimus and cyclosporin work and when are they used?

A

Inhibit calcineurin which normally activates transcription of IL-2 hence reduces T cell proliferation

Used in rejection prophylaxis for transplants

108
Q

How does tofacitinib work and when is it used?

A

Inhibits JAK in RA

109
Q

How does apremilast work and when is it used?

A

PDE4 inhibitor in psoriasis and PA

110
Q

Name some immunosuppressive agents that target cell surface antigens?

A
Basiliximab
Abatacept
Rituximab
Natalizumab
Tocilizumab
Muromonab-CD3
Anti-thymocyte globulin
Daclizumab
Efalizumab
Alemtuzumab
111
Q

Name some immunosuppressive agents that target cytokines?

A
Infliximab
Adalimumab
Certolizumab
Golimumab
Etanercept
Denosumab
112
Q

What is allergen desensitisation?

A

Supervised admin of allergen- tiny dose which is escalated every week- good for bee and wasps, grass pollen, house dust mite but not food or latex