A 65-year-old woman presents with tense, fluid-filled bullae over the flexor surfaces and lower abdomen; the lesions are subepidermal and the oral mucosa is spared. Direct immunofluorescence shows linear deposition of IgG and C3 along the dermoepidermal junction. The autoantigen targeted by these antibodies is:

• A Type VII collagen of the anchoring fibrils
• B Desmoglein 3, a cadherin of the desmosome
• C BP180 (BPAG2), a transmembrane component of the hemidesmosome ✓
• D Alpha 3 chain of laminin 332

Explanation

Bullous pemphigoid is an autoimmune blistering disease caused by IgG against BP180 (also called BPAG2), a transmembrane hemidesmosomal protein linking basal keratinocytes to the basement membrane. Antibody binding triggers complement activation and eosinophil-rich inflammation producing a subepidermal split with tense bullae. Desmoglein 3 is the target in pemphigus vulgaris, which gives intraepidermal acantholysis and flaccid bullae, while type VII collagen is the target in epidermolysis bullosa acquisita.

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.