Increase of CD57+ T cells in knee joints and adjacent bone marrow of rheumatoid arthritis (RA) patients:: implication for an anti-inflammatory role

The distribution of CD57(+) T and CD56(+) T cells in patients with RA was examined. In control osteoarthritis patients, these cells exist as a minor population in the peripheral blood. Our data show that in patients with RA, CD57(+) T cell levels are elevated in peripheral blood, knee joint fluid, knee synovial membrane and bone marrow (BM), compared with peripheral blood of controls. CD57(+) T cells are especially high in knee joint fluid and joint-adjacent BM, while CD56(+) T cells show no such increase. CD57(+) T cells contain a major population of CD8(+) cells and higher proportions of CD4(-)8(-) cells and gamma delta T cells than do CD57(-)T cells. CD57(+)T cells in peripheral blood and joint fluid increase with the duration of disease. Erythrocyte sedimentation rate (ESR) is inversely correlated with the proportion of CD57(+)T cells in the joint fluid. Although RA frequently occurrs in patients with CD3(+)57(+) cell leukaemia, and some CD57(+)T cells are likely to be involved in the onset of RA, we suggest that CD57(+)T cells may rather suppress inflammation of RA, and other cellular components (e.g. granulocytes) may govern the severity of the inflammation of RA. These CD57(+) T cells are probably generated extrathymically in the adjacent BM or joint space.