Associations between B cell subsets and Pemphigus Disease Area Index, immunoglobulin G levels, anti-desmoglein 1 and 3 autoantibody titers in newly diagnosed pemphigus vulgaris patients

Background Pemphigus vulgaris (PV) is a rare autoimmune disease, with its underlying pathological mechanisms still not fully understood despite extensive research. Objective To examine the association between B cell subsets and clinical/serological parameters in newly diagnosed PV patients, including Pemphigus Disease Area Index (PDAI), immunoglobulin G levels, and anti-desmoglein (anti-Dsg)1 and 3 antibody titers. Patients and methods A cross-sectional study of 46 newly diagnosed PV patients was enrolled in Vietnam’s National Hospital of Dermatology and Venereology (April 2023–March 2024). Disease severity was assessed using PDAI. B cell subsets were analyzed via flow cytometry, while anti-Dsg antibodies and immunoglobulin G levels were measured using enzyme-linked immunosorbent assay and indirect immunofluorescence (IIF), respectively. Results Plasmablast percentages correlated with total PDAI ( r =0.36, P =0.02), cutaneous PDAI ( r =0.31, P =0.03), and IIF levels ( r =0.46, P =0.001). Mucosal PDAI showed positive associations with unswitched memory B cells and memory B cell counts ( r =0.31, 0.36, and 0.31, with P =0.04, 0.01, and 0.04, respectively). In mild-to-moderate PV, mucosal PDAI was linked to switched memory B cells ( r =0.52, P =0.048). In severe PV, IIF levels correlated with double-negative B cells and plasmablast percentages ( r =0.53, 0.37, with P =0.002 and 0.04, respectively). Anti-Dsg1 antibody levels in severe PV were associated with regulatory B cells ( r =0.37, P =0.04). Conclusion B cell subsets may play a crucial role in PV clinical manifestations, severity, and autoantibody production, suggesting their potential in predicting therapeutic outcomes for B cell-targeted treatments.