A subepidermal blister with autoantibodies directed against which proteins?

• A. Intracellular adhesion molecule-1
• B. Desmosomal proteins
• C. Collagen type IV
• D. Hemidesmosomal proteins

Answer: (D)

Blisters that occur just above the dermis arise when autoantibodies target components that anchor the epidermis to the underlying dermis. In this classic subepidermal blister, the targets are hemidesmosomal proteins, such as BP180 (collagen XVII) and BP230, which hold basal keratinocytes to the basement membrane. When these proteins are attacked, the junction between epidermis and dermis weakens, and a clear, tense blister forms beneath the epidermis.

Desmosomal proteins, in contrast, are involved in adhesion between keratinocytes within the epidermis; autoantibodies against them cause pemphigus, which produces intraepidermal blisters. Collagen type IV is a basement membrane component, but the typical target for this subepidermal blister scenario is the hemidesmosomal complex rather than collagen IV. ICAM-1 is an adhesion molecule related to inflammatory cell interactions, not the blistering target here.