Lymphocyte subpopulations in rheumatoid synovial tissue.

Synovial tissue obtained at synovectomy of the knee joint in 21 patients with rheumatoid arthritis contained a significantly lower proportion of T lymphocytes as measured by spontaneous rosette formation with nonsensitized sheep red blood cells than did synovial fluid or blood from the same patients. There was on concomitant increase in synovial tissue lymphocytes with B-cell markers such as surface immunoglobulin or Fc fragment receptors. Removal of lymphocyte receptors with trypsin followed by culture to allow new receptors to form, led to an increase in rosette forming cells, suggesting that part of the synovial cells without B- or T-cell markers may be T lymphocytes with blocked receptors.