ABD Basic Science and Immunology 2 — Questions and Answers
Question 1: Which cytokine is the principal driver of the Th2 immune axis implicated in atopic dermatitis?
- IL-4 (Correct answer)
- IFN-gamma
- IL-17
- TNF-alpha
Correct answer: IL-4
IL-4 is the signature Th2 cytokine central to atopic dermatitis pathogenesis and the target of dupilumab.
Question 2: A loss-of-function mutation in the FLG gene predisposes to atopic dermatitis by impairing production of which protein?
- Filaggrin (Correct answer)
- Desmoglein 3
- Collagen VII
- Loricrin
Correct answer: Filaggrin
FLG encodes filaggrin, essential for skin barrier integrity and hydration.
Question 3: Langerhans cells in the epidermis are best characterized by the presence of which cytoplasmic organelle?
- Birbeck granule (Correct answer)
- Weibel-Palade body
- Melanosome
- Odland body
Correct answer: Birbeck granule
Birbeck (tennis-racket) granules are the ultrastructural hallmark of Langerhans cells.
Question 4: Which immunoglobulin class is deposited in the dermal papillae in dermatitis herpetiformis?
- IgA (Correct answer)
- IgG
- IgM
- IgE
Correct answer: IgA
Granular IgA deposits in dermal papillary tips are diagnostic of dermatitis herpetiformis.
Question 5: The type III hypersensitivity reaction responsible for cutaneous leukocytoclastic vasculitis is mediated primarily by:
- Immune complex deposition (Correct answer)
- IgE-mediated mast cell degranulation
- Cytotoxic T cells
- Delayed T-cell response
Correct answer: Immune complex deposition
Type III reactions involve immune complex deposition in vessel walls triggering complement activation.
Question 6: Which structural protein is the target autoantigen in bullous pemphigoid?
- BP180 (collagen XVII) (Correct answer)
- Desmoglein 1
- Desmoglein 3
- Plectin
Correct answer: BP180 (collagen XVII)
BP180 and BP230 are hemidesmosomal antigens targeted in bullous pemphigoid.
Question 7: The Th17 pathway, central to psoriasis, is driven by which key cytokine that is the target of secukinumab?
- IL-17A (Correct answer)
- IL-4
- IL-10
- IL-5
Correct answer: IL-17A
IL-17A is the effector cytokine of Th17 cells and the target of secukinumab in psoriasis.
ABD Basic Science and Immunology 2
Which cytokine is the principal driver of the Th2 immune axis implicated in atopic dermatitis?