Characterization of IL-2 responsive synovial T lymphocytes in rheumatoid arthritis. II. Functional properties.

Lymphocytes from peripheral blood (PBL) and synovial fluid (SFL) were obtained from patients with rheumatoid arthritis (RA) and cloned under limiting-dilution conditions without prior activation but in the presence of exogenous interleukin (IL)-2. The precursor frequencies of such in vivo activated IL-2-responsive cells were higher in RA SFL (1/83) than in RA PBL (1/201) or normal PBL (1/377). These HLA-Dr/Ia-positive clones expressed T-cell markers CD3 and T101 and were either CD4- or CD8-positive but lacked NK markers CD11, CD16, and HNK-1. All such clones were cytotoxic for NK-sensitive K562 targets and NK-insensitive Raji cell targets. These cells, which most closely resemble nonmajor histocompatibility complex (MHC) restricted cytotoxic T (CTL) cells, are present with increased frequency in RA synovial fluids.