EXPRESSION OF THE ACTIVATION ANTIGEN CD27 IN RHEUMATOID-ARTHRITIS

Differentiation of CD4(+) T-cells is reflected by the change from the CD45RA(+)CD27(+) phenotype via CD45RO(+)CD27(+) to the CD45RO(+)CD27(- ) phenotype. To provide insight into the migration and activation of T -cells at the site of inflammation in rheumatoid arthritis (RA), CD27 expression by T-cells in peripheral blood (PB), synovial fluid (SF), a nd synovial tissue (ST) as well as the levels of the soluble form of C D27 (sCD27) in plasma and SF were studied in patients with Rk Since CD 4(+)CD27(+) T-cells are involved in providing helper activity for B-ce lls, we also investigated the levels of rheumatoid factors in serum an d SF in relation to CD27 expression. The mean level of sCD27, which is produced by CD27(+) cells, and the mean percentage of CD27(-) T-cells within the CD4(+)CD45RA(-) subset were higher in SF than in PB. SF sC D27 levels were higher in the patients with RA than in the patients wi th osteoarthritis, who served as controls. In ST infiltration by CD4()CD45RO(+)CD27(+) T-cells could be demonstrated in the rheumatoid peri vascular lymphocytic aggregates with a relative increase in the percen tage of CD27(-) T-cells in the diffuse lymphocytic infiltrate. The sCD 27 levels and the percentages of CD4(+)CD27(+) cells in SF correlated positively with the levels of rheumatoid factors in serum and SF. The findings presented in this study suggest a continuous influx of preact ivated CD4(+)CD45RO(+)CD27(+) cells from the PB into the rheumatoid ST and further activation and differentiation to CD4(+)CD45RO(+)CD27(-) cells in situ, followed by migration to the SF. These activated T-cell s are likely to play a role in synovial inflammation. (C) 1996 Academi c Press, Inc.