DUAL CD45RA, CD45RO POSITIVE T-LYMPHOCYTES WITHIN RHEUMATOID ARTHRITIC JOINTS

This report documents the presence of an expanded population of dual C D45RA, CD45RO positive T cells (up to 91% of T cells) in the rheumatoi d joint. Cells from peripheral blood (PB) and synovial fluid (SF) were analysed by dual immunofluorescence labelling. Synovium from a separa te patient population was analysed by single and dual immunoenzyme sta ining of serial sections. Dual CD45RA, CD45RO positive T cells were fo und in PB (up to 74%), SF (up to 91%) and synovium. This was associate d with a lack of early activation antigens (4F2, interleukin-2 recepto r, transferrin receptor) but increased HLA-Class II antigens (HLA-DR, -DP, -DQ) in SF compared with PB. This intermediate activation phenoty pe may support the hypothesis that T cell activation or reactivation o ccurs within the rheumatoid joint.