043 Deep immunoprofiling in pemphigus reveals significant shifts in dendritic-, natural killer- and T cell compartments at the single-cell level

Abstract

Pemphigus Vulgaris (PV) is a rare, potentially life-threatening blistering disorder of the skin and mucous membranes characterized by IgG autoantibodies directed against specific components of epidermal adhesion structures. Although previous studies have attempted to address changes in immune cell phenotype and frequency in PV largely by flow cytometry, these studies have been limited by the number of parameters that can be simultaneously analyzed, thus restricting its utility. Consequently, the subpopulations of autoreactive and regulatory T and B lymphocytes, and other relevant immune cells that contribute to disease pathogenesis remain topics of intense investigation. In this study, we utilized mass cytometry by time of flight (CyTof), a powerful method with single-cell resolution, to interrogate the phenotype and frequency of a comprehensive range of immune cellular subsets assessed using 30 cellular markers simultaneously in the blood of 12 pemphigus patients and 15 healthy controls. Within the lymphocyte compartment, we observe a marked shift in the CD4/CD8 ratio with a significant increase of CD4 cells and decreased numbers of both CD8 and MAIT/NKT cells in PV patients vs. healthy controls. Across both CD4 and CD8 populations there is a shift from naïve to memory compartments. Among CD4+ cells there is an additional increase in Th2 and Th17 cells, accompanied by a significant decrease in regulatory T cells in PV. In NK cells we observe a shift from early to late cells, while there is no apparent change in overall B cell numbers or subtypes. However, as expected, treatment with the CD20 inhibitor rituximab strongly impacts B cell numbers and distribution. Finally, among dendritic cells, a redistribution from plasmacytoid to myeloid phenotypes is apparent. In summary, our study illuminates previously unattainable details regarding the composition, frequency and phenotype of circulating immune cell subsets in PV to advance our understanding of autoimmune mechanisms.