PT - JOURNAL ARTICLE AU - Saori Hatachi AU - Yoshiko Iwai AU - Seiji Kawano AU - Sahoko Morinobu AU - Masaya Kobayashi AU - Masahiro Koshiba AU - Ryuichi Saura AU - Masahiro Kurosaka AU - Tasuku Honjo AU - Shunichi Kumagai TI - CD4+ PD-1+ T cells accumulate as unique anergic cells in rheumatoid arthritis synovial fluid. DP - 2003 Jul 01 TA - The Journal of Rheumatology PG - 1410--1419 VI - 30 IP - 7 4099 - http://www.jrheum.org/content/30/7/1410.short 4100 - http://www.jrheum.org/content/30/7/1410.full SO - J Rheumatol2003 Jul 01; 30 AB - OBJECTIVE: The PD-1 receptor, whose deficiency in mice causes autoimmune diseases such as arthritis, is considered to be a negative regulator of activated T cells and to play a crucial role in peripheral tolerance. To clarify the involvement of the PD-1 system in rheumatoid arthritis (RA), we investigated PD-1 expression on synovial fluid (SF) T cells from patients with RA. METHODS: FACS analysis for PD-1 was performed on SF T cells from 44 patients with RA and 6 with osteoarthritis (OA), and also on peripheral blood (PB) T cells from 12 RA patients and 7 healthy controls. Two-color analysis of cell surface PD-1 expression and the intracellular concentration of cytokine production was used to investigate CD4+ T cells from SF of patients with RA and PB from controls. RESULTS: Scarcely any PD-1 expression was detected on control PB T or OA SF T cells. In contrast, PD-1+ cells made up 20.9 +/- 8.6% (mean +/- SD) of RA SF T cells. In RA SF, PD-1 was expressed more predominantly on CD4+ T cells than on CD8+ T cells. As well as expressing CD45RO and CXCR3, CD4+ PD-1+ T cells were mostly CTLA-4 positive and CD26 negative, and were enriched in CD45RB(low) cells. Intracellular cytokine staining revealed that CD4+ PD-1+, but not CD4+ PD-1-, T cells produced interleukin 10 (IL-10), and that CD4+ PD-1+ T cells produced less IL-2 than CD4+ PD-1- T cells. CONCLUSION: PD-1+ T cells in RA SF are enriched, and phenotypic analysis suggests that these cells constitute a unique anergic T cell subset in RA SF.