Synovial fluid lymphocytes in different subtypes of juvenile rheumatoid arthritis.

We studied the subsets of synovial fluid (SF) lymphocytes and their activation states in 4 subtypes of juvenile rheumatoid arthritis. The expression of lymphocyte differentiation antigens and activation markers (Ia and Tac) appeared to be similar in these subgroups. Tac + DNA-synthesizing T blasts represented, at most, 5% of all SF mononuclear cells. This finding was in clear contrast to the high proportion of Ia-positive SF mononuclear cells. There were no differences in Ia and Tac expression or DNA synthesis among the different juvenile rheumatoid arthritis subgroups. This finding suggests that the cell-mediated immune response may represent secondary features of the disease that are involved as a final common pathogenetic pathway.