ANALYSIS OF T-CELL SUBSETS PRESENT IN THE PERIPHERAL-BLOOD AND SYNOVIAL-FLUID OF REACTIVE ARTHRITIS PATIENTS

Objective-Reactive arthritis (ReA), a HLA-B27 associated arthropathy, develops in susceptible people after infection with certain bacteria. T cells have been implicated in the pathogenesis of the arthritis but which of the different subsets is involved is still debated. This stud y has further elucidated the role of the CD4(+) and CD8(+) T cells by examining the expression of various surface markers associated with ac tivation. Methods-Three colour flow cytometry was used to examine the phenotype of the T cells within the synovial fluid (SF) and peripheral blood (PB) of ReA patients. Results-ReA SF, compared with paired PB, contained a higher percentage of CD69(+), CD25(+), and HLA-DR+ CD3(+) T cells. The majority of SF T cells also expressed the putative memory marker CD45RO. Within the T cell subsets, CD25 was expressed primaril y on the CD4(+) T cells; however more CD8(+) T cells were HLA-DR+. Con clusion-The results show that both CD4(+) and CD8(+) T cell population s demonstrate evidence of recent activation. Whether these cells are i nvolved in inducing inflammation, regulating the inflammation, or have become active as a result of migration through the endothelium, remai ns to be determined by functional studies.