COMPARATIVE-ANALYSIS OF CD45RA-POSITIVE AND CD45RO-POSITIVE CD4(-BLOOD, SYNOVIAL-FLUID, AND SYNOVIAL TISSUE IN PATIENTS WITH RHEUMATOID-ARTHRITIS AND OSTEOARTHRITIS()T CELLS IN PERIPHERAL)

To determine whether the predominant infiltration with memory CD4(+)T cells in joints is specific to the local immune and inflammatory respo nse in rheumatoid arthritis (RA), the proportions of CD45RA(+) or CD45 RO(+) cells in the CD4(+)T cell populations in three different compart ments (i.e., peripheral blood, synovial fluid, and synovial tissue) fr om patients with RA and osteoarthritis (OA) were compared by two-color flow-cytometric analysis. In the CD4(+)T cell population of periphera l blood, the number of CD45RO(+) cells was relatively higher than CD45 RA(+) cells in both RA and OA patients, but their percentages did not differ from those found in healthy individuals. However, the great maj ority of CD4(+)T cells present in synovial fluid and synovial tissue w ere CD45RO-positive and CD45RA-negative in both patient groups; althou gh CD4(+)T cells infiltrating both the disease compartments were marke dly greater in RA joints, their mean percentages of CD45RO(+) cells we re not significantly different from those in OA joints. These data ind icate that an accumulation of CD45RO(+) memory CD4(+)T cells is a gene ralized phenomenon during local inflammatory responses in both RA and OA joints, and may be due mainly to the propensity of these cells to p referentially transmigrate into the inflamed joint via adhesion molecu les as compared with CD45RA(+) naive CD4(+)T cells.