Rituximab remodels the circulating immune landscape in pemphigus vulgaris revealed by high-dimensional immune profiling.

Pemphigus vulgaris (PV) is a severe autoimmune blistering disease characterized by pathogenic autoantibodies primarily targeting desmoglein-3. B-cell depletion by rituximab (anti-CD20) is an effective first-line treatment for PV; however, relapses are frequently observed. Evidence suggests that PV is associated with immune dysregulation beyond the B-cell compartment. So far, existing studies have largely focused on selected immune components or populations, or specific clinical states such as active disease, remission, or immediate post-rituximab, leaving it unclear how prior rituximab treatment shapes the overall circulating immune landscape during active PV, including relapse. In this study, we performed high-dimensional immune profiling to characterize circulating immune-cell composition and cytokine/chemokine signatures using a 40-colour spectral flow cytometry panel and a 46-plex Luminex assay, respectively. We compared active PV patients with healthy controls and performed a subgroup analysis of rituximab-naive versus rituximab-experienced relapsed PV patients. High-dimensional immune profiling showed that active PV is associated with a redistribution of circulating immune cells, with increased monocytes and decreased lymphocytes and plasmacytoid dendritic cells, together with reduced frequencies of double-negative (CD4-CD8-) T cells and T follicular helper cells compared with healthy controls. When comparing rituximab-naive with rituximab-experienced PV patients, in rituximab-experienced patients, the cellular composition changes were confined to the B-cell compartment, showing a shift toward a naive-dominant B-cell subset distribution. In parallel, PV was characterized by elevated serum concentrations of CD40L, CCL11/eotaxin, G-CSF, IL-1RA, IL-7, CCL20/MIP-3α, PD-L1/B7-H1/CD274, PDGF-AB/BB, and CCL5/RANTES, while no differences were identified between rituximab-naive patients and rituximab-experienced relapsed PV patients. Correlation analysis revealed that prednisone dosage may increase the frequency of mature B cells, and levels of CCL11/eotaxin, and IL-7, while decreasing the frequency of plasmacytoid dendritic cells and T follicular helper cells. Together, these findings reveal a systemic immune signature of active PV involving changes in circulating monocyte, T-cell, and soluble immune compartments, whereas prior rituximab exposure in relapsed patients is associated with sustained remodelling confined to B-cell subset composition, without long-term restructuring of non-B-cell immune lineages.