Immuno/Allergy

Question 1

Skin bx of a child demonstrates vascular lesions with IgA and C3 deposition. Dx?

Answer 1

Henoch-Schonlein purpura
Kids 3-11
Skin rash, abd pain, glomerulonephritis, end-stage renal dz

Question 2

Following drug admin pt presents with difficulty breating, abdominal cramps, hypotension. Dx and tx?

Answer 2

Anaphylactic shock
Epinephrine to stabalize, can consider diphenhydramine for tx after that
hypotension is due to collapse of peripheral vascular resistance, increased vascular permeability, leakage of capillary fluid

Question 3

1st gen antihistamines are contraindicated in elderly pts. What could be used?

Answer 3

2nd gen
loratadine, cetirizine
don’t cross BBB, nonsedating

Question 4

Kid is found to have decreased serum complement C4 and C1 esterase inhibitor levels. What drug is contrindicated

Answer 4

Captopril
Hereditary angioedema (AD), low C1 esterase inhibitor activity leads to increases in bradykinin activity. Avoid all ACEI because they further increase bradykinin

Question 5

Inhibition of which substance specifically reduces the proliferation and differentiation of T cells?

Answer 5

Calcineurin
Calcineurin is essential in the activation of IL2
Cyclosporine and tacrolimus inhibit calcineurin

Question 6

What would be elevated in a pts serum during anaphylaxis?

Answer 6

Preformed inflammatory mediators, histamine, tryptase

Tryptase - specific to mast cells and used as a marker for mast cell activation

Question 7

What is 5-hydroxyindoleacetic acid?

Answer 7

Breakdown product of serotonin

Used to screen for carcinoid syndrome

Question 8

When IgE binds mast cells and basophils, which mechanism will trigger the release of vasoactive substance?

Answer 8

Receptor aggregation
Cross-linking of multiple membrane bound IgE ab by a multivalent Ag results in aggregation of the IgE receptor -> degranulation -> release of preformed mediators (histamine, tryptase) that initiate an allergic response