CHARACTERIZATION AND REGULATION OF CD69 EXPRESSION ON RHEUMATOID-ARTHRITIS SYNOVIAL-FLUID T-CELLS

Objective, To study CD69+ synovial fluid (SF) T cells and the mechanis ms regulating CD69 expression in rheumatoid arthritis (RA). Methods, O ne or 2 color flow cytometry was used to determine CD69 and other surf ace markers. Cultures of SF T cells alone or mixed with autologous SF non-T cells were used for CD69 maintenance assays. Results, SF T cells were enriched in CD69+. These cells were mainly CD3+, CD8+ and CD25-. CD69 was maintained on SF T cells cultured with SF non-T cells but no t when the former were cultured alone or in the presence of different supernatants from RA SF T and non-T cells cultures with sustained CD69 expression. Pretreatment of T and non-T cells with anti-CD18 monoclon al antibody inhibited CD69 expression, while paraformaldehyde-''fixed' ' non-T cells effectively maintained it. Conclusion. SF T cells exhibi t a phenotype with evidence of past and recent activation. Our studies demonstrate that most of the recently activated SF T cells are CD8+. We also found that continuous cell-to-cell interaction between T and n on-T cells are responsible for the maintenance of this particular stat e of activation of SF T cells.