Immunology

Question 1

What mutations results in X linked agammaglobulinaemia

Answer 1

Mutation in Bruton’s tyrosine kinase
Responsible for B cell maturation
Absence results in nil B cells or Ig
Susceptible for bacterial sinopulmonary infections, giardia, campylobacter, enteroviruses

Question 2

What is Bruton’s tyrosine kinase

Answer 2

Gene responsible for B cell maturation

Absence results in nil B cells or Ig - X linked agammaglobulinaemia

Question 3

What is CVID

Answer 3

Common Variable Immunodeficiency
Polygenic
Low IgG +/- IgM/IgA, Normal B cell count
Predisposes to sinopulmonary and GI diseases

Question 4

Management of CVID

Answer 4

IVIg
Avoid live vaccines
Antibiotics

Question 5

Mechanism of hyperIgM disease

Answer 5

Failure to class switch and generate memory B cells
Multiple genetic mutations but most common due to absence of CD40L on T cell (X-linked)
Predisposes to sinopulmonary and GI diseases and PCP (?CD40L plays role in T cell activation?)

Question 6

Diagnostic test for specific antibody deficiency

Answer 6

Failure to respond to polysaccharide vaccines

Normal Ig levels, B cells present

Question 7

CD4 count low, HIV negative - what is diagnosis? What needs to be ruled out?

Answer 7

CD4 lymphopenia (rare)
Rule out T cell lymphoma
Predisponse to T cell infections: Candidiasis, MAC, VZV, Crytococcus, PCP, viral
Rx: Infection prophylaxis

Question 8

What causes chronic mucocutaneous candidiasis

Answer 8

Deficiency of Th17 cells
Multiple genes implicated
Recurrent candida on skin, nails, oesophagus, pulmonary, mucosa

Question 9

Iron deficiency linked to what infection

Answer 9

Candida

Question 10

Deficiency in C3 results in susceptibility to what?

Answer 10

Recurrent pyogenic infections
Immune complex disease
Glomerulonephritis

Question 11

Breakdown of lymphocyte subsets (%)

Answer 11

T cells 70% (2/3 CD4, 1/3 CD8, ratio 2:1)
B cells 15%
NK cells 15%

Question 12

What test is used for chronic granulomatous disease?

Answer 12

Neutrophil oxidative metabolism to look for neutrophil function - deficient in NADPH Oxidase
Multiple genetic mutations

Question 13

describe the classical pathway for complement activation

Answer 13

Ag Ab complex (IgG or IgM) binds to C1 and activates it
activated C1 combines 4b and 2a via C3 convertase
feeds into terminal pathway
measure via: C1q binding assay; CH50 - measures classical and terminal pw

Question 14

alternate pathway complement activation

Answer 14

C3 –> C3b wiht C3 convertase to form C3bBb3B; feeds into terminal pw
measure: AH50 (alternate and terminal)

Question 15

Type I - Anaphylactic

Answer 15

• antigen reacts with IgE bound to mast cells

* anaphylaxis, atopy (e.g. asthma, eczema and hayfever)

Question 16

Type II - Cell bound

Answer 16

• IgG or IgM binds to antigen on cell surface
• autoimmune haemolytic anaemia, ITP, Goodpasture’s, pernicious anemia, acute hemolytic transfusion reactions, rheumatic fever, bullous pemphigoid, pemphigus vulgaris

Question 17

Type III - Immune complex

Answer 17

• free antigen and antibody (IgG, IgA) combine
• serum sickness, systemic lupus erythematosus, post-streptococcal glomerulonephritis, extrinsic allergic alveolitis (especially acute phase)

Question 18

Type IV - Delayed hypersensitivity

Answer 18

• T cell mediated
• tuberculosis, tuberculin skin reaction, graft versus host disease, allergic contact dermatitis, scabies, extrinsic allergic alveolitis (especially chronic phase), multiple sclerosis, Guillain-Barre syndrome

Question 19

Type V

Answer 19

• antibodies that recognise and bind to the cell surface receptors, either stimulating them or blocking ligand binding
• Graves’ disease, myasthenia gravis

Question 20

acquired angioedema

Answer 20

> 40yo
rare
C1 inhibitor deficiency
associated with lymphomas

Question 21

hereditary angioedema

Answer 21

mainly Dx < 20yo
C1 inhibitor deficiency (normally breaks down bradykinin)
low C4

Question 22

CH50

Answer 22

assesses classical complement pathway
C1-9
if any one is low then total CH50 will be low

Question 23

carbamazepine han chinese

Answer 23

HLAB 1502

Question 24

allopurinol han chinese

Answer 24

HLA 5801

Question 25

Wiskott-Aldrich syndrome

Answer 25

recurrent bacterial infections (e.g. Chest)
eczema
thrombocytopaenia

Question 26

allergy testing

Answer 26

skin prick - food allergies, pollen - don’t do if hx anaphylaxis
RAST - specific IgE - use when can’t skin prick - eczema, anti histamines, anaphylaxis
skin patch - contact dermatitis

Question 27

C1q deficiency

Answer 27

90% of people will develop SLE

have recurrent infections

Question 28

Hyper IgM syndrome

Answer 28

defect in CD40 Ligand on activated T cells

Question 29

wheat dept exercise induced anaphylaxis

Answer 29

specific IgE to omega 5 gliadin