A nurse develops intensely itchy, vesicular dermatitis on her hands 48 hours after wearing new latex-containing gloves containing rubber accelerators. Patch testing reproduces the lesion. Which cell population is the principal effector of this eruption?

• A Neutrophils recruited by C5a
• B Natural killer cells recognizing Fc-bound targets
• C Mast cells releasing preformed histamine granules
• D CD4+ TH1 cells releasing IFN-gamma and recruiting macrophages ✓

Explanation

Allergic contact dermatitis is a Type IV delayed-type hypersensitivity reaction. The hapten penetrates skin, binds carrier proteins, is processed by Langerhans cells, and sensitizes CD4+ TH1 cells. On re-exposure these cells secrete IFN-gamma and TNF, recruiting macrophages and producing the eczematous vesicular lesion over 24 to 72 hours. The delayed onset and positive patch test distinguish it from irritant dermatitis. Option C fails because histamine-mediated responses occur within minutes and are not reproducible by patch testing at 48 hours.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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