## Autoantigen in Pemphigus Vulgaris **Key Point:** Pemphigus vulgaris is caused by IgG autoantibodies directed against desmogleins, which are transmembrane glycoproteins of the desmosome. ### Desmoglein Targets | Feature | Desmoglein 3 | Desmoglein 1 | | --- | --- | --- | | **Location** | Basal and suprabasal layers | Superficial layers | | **Clinical Pattern** | Mucosal involvement (always) | Cutaneous involvement | | **PV Presentation** | Anti-Dsg3 alone = mucosal PV | Anti-Dsg3 + Anti-Dsg1 = mucocutaneous PV | **High-Yield:** Anti-desmoglein antibodies are pathogenic and directly cause acantholysis through disruption of cell-cell adhesion in the epidermis. The pattern of antibodies correlates with clinical phenotype. **Clinical Pearl:** Serum anti-desmoglein antibody titers correlate with disease activity and can be used to monitor treatment response. ### Why Other Antigens Are Wrong - **Desmocollin 1**: A minor component of desmosomes; not the primary target in PV. - **BP180 (collagen XVII)**: Target antigen in bullous pemphigoid (subepidermal blistering), not PV. - **Integrin α6β4**: Also involved in bullous pemphigoid pathogenesis, not PV. 
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