E‐cadherin autoantibody profile in patients with pemphigus vulgaris

Summary Background Pemphigus vulgaris ( PV ) is an autoimmune skin blistering disease. The main targets of autoantibodies are the desmosomal proteins desmoglein ( D sg)3 and D sg1. Anti‐ E ‐cadherin antibody is the second most frequent antibody found in pemphigus foliaceus (fogo selvagem), but the frequency in PV is unknown. Objectives To determine the anti‐ E ‐cadherin antibody profile in the two major subtypes of PV : mucosal PV (m PV ) and mucocutaneous PV (mc PV ). Methods Sera from 80 patients with PV and 80 controls were tested. Patients with PV were subdivided into m PV ( n  =   18) and mc PV ( n  =   62). Samples were tested by E ‐cadherin, D sg1 and D sg3 enzyme‐linked immunosorbent assays ( ELISA s), and immunoprecipitation coupled with W estern blotting ( IP ‐ WB ). Results Both m PV and mc PV sera have antibodies against E ‐cadherin as demonstrated by ELISA and IP ‐ WB . Both subtypes of PV have low levels of anti‐ E ‐cadherin antibodies, but significantly higher levels than healthy controls by ELISA ( P  <   0·0001). No difference exists in antibody levels between subgroups ( P  =   0·82). By IP ‐ WB , 78% of mc PV sera reacted to E ‐cadherin, vs. 33% of m PV sera tested. Correlation analysis suggests a moderate correlation between anti‐ E ‐cadherin antibodies and D sg1antibodies (average r  =   0·61), but no correlation with D sg3 antibodies (average r  =   0·19). Patients with m PV can have lower levels of D sg1 antibodies compared with controls by ELISA ( P  <   0·0001). A few m PV sera also reacted to D sg1 protein by IP ‐ WB (17%). Conclusions Anti‐ E ‐cadherin antibodies are present in both major subtypes of PV . A moderate correlation exists between E ‐cadherin and D sg1 antibodies. Patients with m PV can have low levels of both E ‐cadherin and D sg1 antibodies.