The cytotoxicity of leukocytes and lymphocytes from patients with rheumatoid arthritis for synovial cells.

Unseparated peripheral blood leukocytes obtained from patients with rheumatoid arthritis (RA) were cytotoxic for synovial cells. The cytotoxic reactions produced by RA leukocytes were more frequent and of greater magnitude than cytotoxicity induced by leukocytes from normal persons and patients with other diseases, primarily connective tissue diseases. Furthermore, the cytotoxic activity of RA leukocytes was greater for RA synovial cells than for nonrheumatoid synovial cells, in contrast to the cytotoxicity of other leukocytes, which did not discriminate between synovial cells according to their origin. Tests with purified lymphocytes showed that the cytotoxicity of unseparated leukocytes directed against RA synovial cells was due to lymphocyte cytotoxicity. These data are consistent with the possibility that sensitized lymphocytes from patients with RA recognize a distinctive antigen present on rheumatoid synovial cells.