Increased population of high fluorescence 1F7 (CD26) antigen on T cells in synovial fluid of patients with rheumatoid arthritis.

To investigate the activation of T cells in peripheral blood (PB) and synovial fluid (SF) of patients with rheumatoid arthritis (RA). The expression of CD26 (Ta1 and 1F7) antigen on T cells was analyzed in 7 women with RA and 7 healthy control subjects by immunofluorescence. The percentage of CD3+ CD26+ cells was significantly higher in PB of patients with RA compared with healthy subjects. The IF7+ cell population was divided into high (1F7+high cells) and low fluorescence populations (1F7+low cells), based on 1F7 antigen density. The percentage of 1F7+high cells in SF of RA was markedly increased compared with PB of patients and healthy subjects. However, RA SF contained lower percentages of whole 1F7+ cells compared with PB. Our results indicate that SF of patients with RA contains activated T cells, and suggest that T cells with high levels of CD26 antigen may preferentially migrate into the rheumatoid synovium to induce inflammation and tissue destruction.