| Abstract: | Objective. To determine if the T cell antigen receptor Vβ usage of unstimulated rheumatoid arthritis (RA) synovial fluid (SF) T cells is biased compared with those in peripheral blood (PB). Methods. Freshly isolated, matched synovial fluid and peripheral blood T cells were analyzed for Vβ gene expression using quantitative polymerase chain reaction (PCR) methods. Ten synovial fluid samples from the knees of 7 patients with RA were studied. The PCR assay used 26 Vβ primers with a constant region Cβ primer, and 2 Cα primers that co-amplified a product that served as an internal standard. Cycle number and complementary DNA content were controlled to ensure the linear accumulation of PCR products. Labeled products were separated on 10% polyacrylamide gels and counted with a Betascope blot analyzer. Results. There were consistent differences between the Vβ gene usage of SF and PB T cells directly isolated from patients with RA, regardless of HLA–DR haplotype. In all synovial specimens, Vβ2 was increased relative to the peripheral blood, while Vβ13.1 and Vβ13.2 were decreased. Vβ6 and Vβ21 were increased in 9 of the 10 synovial samples. Analyses of bilateral SF specimens from 2 subjects and serial specimens from the same knee of 1 subject revealed virtually identical patterns in each patient. The SF Vβ bias was not solely due to differences in the proportion of CD4+ and CD8+ cells, because the CD4:CD8 ratios in SF and PB were similar. However, Vβ gene usage of separated CD4+ and CD8+ synovial T cells showed that Vβ2 and Vβ6 were more highly expressed on CD4 cells. Conclusion. Freshly isolated synovial T cells from inflamed (not end-stage) knees of patients with RA have a remarkably consistent biased Vβ gene usage compared with PB T cells. Vβ2 and Vβ6 are uniformly increased, and this increase is primarily in CD4+ T cells. The same Vβ bias in the SF T cells of several RA patients suggests that shared antigens may be stimulating the T cell response. |
