Pemphigus is a severe autoimmune blistering disorder characterised by circulating autoantibodies against desmogleins and tissue-bound immunoglobulin deposits. Objective To evaluate the association between the intensity of IgG and complement component 3 (C3) deposits detected by direct immunofluorescence (DIF) and serum anti-desmoglein 1 (Dsg1) and 3 (Dsg3) antibody levels measured by ELISA. Methods Single-centre prospective observational cross-sectional study of 50 patients with pemphigus (42 pemphigus vulgaris, 8 seborrheic pemphigus). Serum anti-Dsg1/anti-Dsg3 antibodies were measured in all 50 patients; DIF was performed in 39 patients, and all deposit-intensity analyses and correlations are therefore based on n = 39. Results All 39 DIF-examined patients showed the characteristic intercellular reticular IgG pattern. IgG deposition intensity correlated positively with anti-Dsg3 (rs = 0.71, 95% CI 0.48–0.85; p < 0.001) and anti-Dsg1 (rs = 0.67, 95% CI 0.42–0.82; p < 0.001). Mean antibody levels rose progressively across weak, moderate and strong deposit groups; strong IgG deposits were associated with about 2.3-fold higher anti-Dsg1 levels than weak deposits. The two subtypes showed distinct serological profiles: pemphigus vulgaris showed predominant anti-Dsg3 elevation, whereas seborrheic pemphigus showed predominant anti-Dsg1 elevation (p = 0.04, n = 6). IgG and C3 deposit intensity were strongly correlated (rs = 0.78, 95% CI 0.59–0.89; p < 0.001), a pattern consistent with complement participation. Conclusion In this cross-sectional sample, the intensity of tissue-bound IgG and C3 deposits was positively associated with circulating anti-desmoglein antibody concentrations. DIF and ELISA appear to provide complementary information; prognostic value cannot be inferred from these cross-sectional data.
