## Autoantigen in Pemphigus Vulgaris **Key Point:** Pemphigus vulgaris is an autoimmune disorder caused by IgG autoantibodies directed against desmogleins, which are calcium-dependent adhesion molecules in the desmosome. ### Target Antigens | Pemphigus Type | Primary Autoantigen | Secondary Autoantigen | Clinical Presentation | |---|---|---|---| | Vulgaris | Desmoglein 3 (Dsg3) | Desmoglein 1 (Dsg1) in mucocutaneous form | Mucosal involvement, flaccid blisters | | Foliaceus | Desmoglein 1 (Dsg1) | None | Superficial blisters, no mucosal involvement | **High-Yield:** - **Desmoglein 3 (Dsg3)** = mucosal pemphigus vulgaris (anti-Dsg3 alone) - **Desmoglein 3 + Desmoglein 1** = mucocutaneous pemphigus vulgaris (anti-Dsg3 + anti-Dsg1) ### Mechanism of Acantholysis Autoantibodies bind to desmogleins on the surface of keratinocytes → disruption of cell-cell adhesion → loss of intercellular connections → acantholysis (intraepidermal blister formation). **Clinical Pearl:** The presence of anti-Dsg1 antibodies correlates with more extensive cutaneous involvement, whereas anti-Dsg3 alone predicts mucosal-dominant disease. **Warning:** Desmoplakin and plakoglobin are intracellular plaque proteins, not primary antigens in pemphigus vulgaris. BP180 is the target in bullous pemphigoid (a subepidermal blistering disorder). Integrin α6β4 is involved in hemidesmosomes, not desmosomes. 
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