Proliferating Cells in the Synovial Fluid in Rheumatic Disease

Abstract

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 auto-radiography-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.