Identical T-cell expansions in the colon mucosa and the synovium of a patient with enterogenic spondyloarthropathy

intestinal T lymphocytes activated by antigen are suspected to play a key r ole in enterogenic spondyloarthropathies (SpA). Therefore, we aimed to iden tify and functionally characterize T-cell clones that ave coexpanded in the intestinal mucosa and the synovium. Colon, peripheral blood, and synovium of a patient with enterogenic SpA were screened for clones T-cell expansion s by TCRB-CDR3 length analysis and sequencing. T-cell clones expanded in vi vo were isolated from archived synovial cells by targeted T-cell cloning an d characterized for phenotype, cytokine production, and antigen specificity . The synovial TCRBV18(+) T-cell repertoire of the patient was dominated by 2 CD8(+) T-cell clones using related CDR3. Both clones were expanded throu ghout the colon and were present in the peripheral blood. Upon in vitro sti mulation with PDB/ionomycin, they showed predominantly interferon gamma and interleukin (IL)-4 but also tumor necrosis factor cu and IL-10 production and did not specifically lyse autologous T-cell blasts, B-cell lines, or ot her autologous or allogeneic target or CD1d-transfected cells. These findin gs strongly suggest that T lymphocytes activated by antigen in the intestin al mucosa contribute to joint inflammation in enterogenic SPA by recognitio n of antigens specific for the inflamed synovium.