OP0018 SINGLE-CELL ANALYSIS REVEALS FUNCTIONAL HETEROGENEITY OF PERIPHERAL HELPER T CELLS IN THE SYNOVIUM OF RHEUMATOID ARTHRITIS

Background Rheumatoid arthritis (RA) is a chronic autoimmune disorder that mainly affects the joints. The synovium primary site of inflammatory process, in which local immune response develops. Peripheral helper T cells (Tph) are population CXCR5 - PD1 hi CD4 + thought to provide help for ectopic B cell response. However, whether there heterogeneity among Tph not clear. Objectives To identify functional RA patients. Methods Single-cell RNA sequencing (scRNA-seq), single-cell repertoire (scTCR/BCR-seq), high-dimensional flow cytometry, multiplex immunohistochemistry (mIHC) used study synovial and from subsets were sorted their effect on differentiation. Furthermore, spatial features potential clinical relevance investigated. Results scRNA-seq analysis indicates can be divided into two subsets: LAG3 , validated by cytometry mIHC. Transcriptome analyses reveal more activated exhausted than cells, with former highly expressing panel markers including TIM3, TIGIT, TOX. By contrast, express higher levels molecules related help, MAF IL-21. In assays, potent promote plasma differentiation immunoglobulin secretion cells. Cell ligand-receptor mIHC uncovered close interactions between cells/plasma Conclusion Synovial patients subsets, primarily responsible help. A better understanding may clues develop novel therapeutic strategies RA. REFERENCES: NIL. Acknowledgements: Disclosure Interests None Declared.