SPONTANEOUS AND INVITRO ACTIVATION OF SYNOVIAL-FLUID AND PERIPHERAL-BLOOD LYMPHOCYTES IN RHEUMATOID-ARTHRITIS

Peripheral blood (PB) and synovial fluid (SF) were compared in parallel samples in rheumatoid arthritis (RA). The kinetics of in vitro T-cell activation was assessed in phytohemaglutinin (PHA) stimulated PB or SF mononuclear cell cultures on days 0, 1, 3 and 5. The early lymphocyte activation as assessed by interleukin-2 receptor expression was faster in SF than in PB cell cultures. In particular, IFN-γ secretion was higher in SF than in PB cell cultures (p<0.01). Accordingly, lymphocyte major histocompatibility complex (MHC) locus II antigen expression was higher in SF than in PB cell cultures (53± 7% vs. 21 ± 5%;p<0.01). Our results suggest that lymphocytes, which are particularly effective producers of IFN-γ when stimulated in vitro are sequestered in the diseased joints in RA. © 1990 Springer-Verlag.