CD26 SURFACE-MOLECULE INVOLVEMENT IN T-CELL ACTIVATION AND LYMPHOKINESYNTHESIS IN RHEUMATOID AND OTHER INFLAMMATORY SYNOVITIS

T cell surface expression and the functional role of CD26 antigen (Ag) , a surface ectoenzyme involved in T cell activation and migration acr oss the extracellular matrix, were analyzed in the peripheral blood (P B) and synovial fluid (SF) from patients with inflammatory arthritides . CD26 membrane expression on T cells was detected by cytofluorometry using two different monoclonal antibodies, anti-Ta1 and anti-1F7, whil e cell proliferation and both IL-2 and IFN-gamma production were evalu ated in anti-CDS- or anti-CD2-stimulated cell cultures after Ag surfac e modulation with anti-1F7. The results showed that Ta1 and 1F7 Ag exp ression were increased on T cells from PB of patients with active, but not inactive, rheumatoid arthritis (RA). Most SF T cells from RA or o ther inflammatory arthritides displayed the memory marker CD45RO and t he Ta1 Ag, but lacked the 1F7 molecule. In addition, in vitro 1F7 modu lation, which enhanced RA PB T cell proliferation and both IL-2 and IF N-gamma synthesis, did not synergize with anti-CD3 or anti-CD2 in indu cing IL-S-dependent activation of SF T cells, but reduced IFN-gamma pr oduction. A spontaneous reappearance of 1F7 Ag on the SF T cell surfac e was seen after 2-5 days in culture. Phorbol myristate acetate, able to accelerate its reexpression, also restored a normal response of SE T cells to anti-1F7 comitogenic effects. These data confirm a role of the CD26 surface molecule in regulating T cell activation and lymphoki ne synthesis. This observation,may have important implications in the regulation df T cell activity at the joint level during chronic inflam matory processes. (C) 1996 Academic Press, Inc.