A 35-year-old nurse develops well-demarcated erythema, vesicles, and crusting on the dorsum of both hands after starting use of latex gloves. Patch testing shows a positive reaction to latex at 48 and 72 hours. What type of hypersensitivity is responsible?

• A Type I (IgE-mediated immediate hypersensitivity)
• B Type II (cytotoxic hypersensitivity)
• C Type IV (delayed-type hypersensitivity) ✓
• D Type III (immune complex-mediated hypersensitivity)

Explanation

Allergic contact dermatitis (ACD) is a classic example of Type IV (delayed-type, cell-mediated) hypersensitivity. On first exposure, the hapten-carrier complex sensitizes T-lymphocytes (sensitization phase). On re-exposure, sensitized T cells release cytokines causing the eczematous reaction at 48-72 hours (elicitation phase). Patch testing at 48 and 72-hour readings is diagnostic. Type I hypersensitivity to latex causes immediate urticaria and anaphylaxis, not the delayed eczematous reaction of ACD.

Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.