A 30-year-old woman develops intensely pruritic vesicular lesions on the dorsum of her fingers and wrist two days after wearing a new metal-buckled bracelet. Skin biopsy shows spongiotic vesicles with perivascular lymphocytic infiltrate containing eosinophils. Which cell type is responsible for presenting the causative hapten to T lymphocytes in this reaction?

• A Langerhans cells ✓
• B Mast cells
• C Neutrophils
• D Plasma cells

Explanation

Allergic contact dermatitis from nickel is a Type IV hypersensitivity reaction. Nickel acts as a hapten that binds skin proteins, and Langerhans cells, the dendritic cells of the epidermis, process the haptenated protein and present it to CD4+ T cells in regional lymph nodes, generating memory T cells that mediate the lesion on re-exposure. Mast cells mediate immediate Type I reactions, and plasma cells are absent from the effector phase of delayed hypersensitivity.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.