Cytokines in Chronic Inflammatory Arthritis

Current models of rheumatoid arthritis (RA)' implicate lymphokines in the recruitment and activation of T cells in the synovium (1, 2) . However, adequate documentation of significant amounts of these proteins in the joint is limited . In fact, recent studies have found only very low levels of IFN-y in synovial fluid (SF) and tissue of patients with RA (3) . This relative lack of IFN-y seems contradictory in light of morphologic and immunohistochemical evidence of T cell activation in the RA synovium (4-6) . Because of this paradox, we decided to study two other T cell lymphokines (IL-2 and IL-3) in rheumatoid synovitis . In this study, we report that neither IL-3 RNA transcript nor IL-2 could be detected in rheumatoidjoint samples . However, colonystimulating factor (CSF) and mast cell growth factor (MCGF) were observed. These data support the notion that T cell lymphokines are not abundant in the rheumatoid joint and that most soluble inflammatory mediators appear to be produced by macrophages, synovial lining cells, fibroblasts, and endothelial cells in the synovium .