Proliferating cells in the synovial fluid in rheumatic disease. An analysis with autoradiography-immunoperoxidase double staining.

The subtype of the proliferating cells in the synovial fluid of patients with rheumatoid arthritis (RA), ankylopoietic spondylarthrosis (SPA), and osteoarthritis (OA) was studied with autoradiography-immunoperoxidase double staining. Of all spontaneously proliferating synovial fluid cells in chronic arthritis, 59 +/- 4% displayed T8 differentiation marker, whereas T4 (21 +/- 4%) and B (2 +/- 1%) cells were few. Of all T4+ and all T8+ lymphocytes, 0.55 +/- 0.1% and 0.90 +/- 0.1%, respectively, incorporated [3H]thymidine. The [3H]thymidine labelling index for B cells was 0.30 +/- 0.1%. This was in contrast to OA, in which no proliferating lymphocytes were observed in the synovial fluid. Our findings suggest that the predominance of proliferating T8+ cells in the synovial fluid reflects an underlying chronic inflammation. Because RA and SPA synovium is a site of intense immunoglobulin production, our finding of the predominance of activated, proliferating T8+ cells may also reflect a dissociation between phenotype and function as a reason for the chronicity of the joint inflammation.