EXPRESSION OF MACROPHAGE MARKERS BY A POPULATION OF T-CELLS OBTAINED FROM SYNOVIAL-FLUID OF A SUBGROUP OF PATIENTS WITH JUVENILE RHEUMATOID-ARTHRITIS

Objective. To characterize distinctive lymphoid cell populations in th e synovial fluid (SF) of patients with juvenile rheumatoid arthritis ( JRA) that have the specific ability to display monocytic markers when cultured in vitro. Methods. Mononuclear cells obtained from SF of pati ents with JRA and depleted of adherent macrophages were cultured in vi tro in RPMI 1640 medium supplemented with only fetal calf serum (FCS). Phenotypic evaluation of these cells was by flow cytometry and immuno histochemical analysis was by specific fluorochrome labeled antibodies . Results, T cells from a JRA subgroup displayed some typical macropha ge attributes, i.e., abundant cytoplasm, adherence to plastic, and pha gocytosis of latex beads when cultured irt vitro. These cells have the ability to survive in culture for several weeks in RPMI 1640 medium c ontaining only 10% FCS, The macrophage-like T cells rosetted with shee p red blood cells and proliferated when stimulated with phytohemagglut inin or anti-CD3, indicating functional T cell responses. Conclusion. Our data indicate that a population of T cells obtained from the SF of a subgroup of patients with JRA exhibited characteristics of macropha ges, yet retained their CD3 and T cell receptor expression. Whether th is promiscuous behavior is caused by malignant transformation of lymph oid precursor cells or is induced by the concerted effect of a myriad of cytokines and growth factors present in the SF remains unknown. The presence of these cells in the SF of 2 patients with JRA with differe nt onset types raises the question of their function and significance in an autoimmune disorder such as JRA.