Identifizierung autoreaktiver T-Zellen bei Patienten mit Pemphigus Vulgaris mittels MHC-II-Dextramere

Pemphigus vulgaris (PV) belongs to the group of autoimmune bullous diseases. Autoreactive Dsg3-specific T cells play a central role in PV pathogenesis by adjusting antibody production directed against Dsg3. Above all, the maintenance of immunological self-tolerance is controlled by regulatory T cells, whose reduction in number or functionality leads to an autoreactive immune response. The focus of the present work is the application of dextramer-Dsg3 peptide staining for the detection of living peripheral CD45 + CD19 - CD14 - CD3 - CD4 + Dsg3 peptide-specific T cells. After stimulation with recombinant Dsg3(aa1-566) of PBMC acquired from PV patients and volunteers, the reactivity of the latter T cell subpopulation against dextramer-Dsg3 peptide mix (Dsg3(aa190-204), Dsg3(aa206- 220), Dsg3(aa254-268), Dsg3(aa378-392)) and against individual dextramer Dsg3 peptides using flow cytometric measurement. Overall, the magnitude of dextramer Dsg3 peptide reactivity is higher in PV patients than in healthy subjects, however, only a significant difference (*p=0.0263) can be observed between these two groups when staining the dextramer pool is applied. As a result of stratification by therapy, reactivity against dextramer Dsg3 peptide pool in PV patients without therapy is not significantly higher than in patients receiving therapy. The comparison between active PV patients and in remission PV patients also shows no significant difference. Interestingly, PV patients show higher reactivity against Class II-associated invariant chain peptides (CLIP) than healthy controls. On the one hand, dextramer staining is an excellent method for detecting antigen-specific T cells, on the other hand, dextramer technology enables specific HLA-restricted epitopes to be examined. As a result, it can lead to a more complete understanding of the role of autoreactive CD4+ T cells in the pathogenesis of the autoimmune response and how epitope spreading characterizes different stages of the disease. In addition, dextramer antigen specificity determination allows obtaining important information regarding T-cell reactivity, which could be used for the development of regulatory T-cell immunotherapy, such as chimeric antigen receptor (CAR) therapy.