en علوم پایه پزشکی Basic Medical Sciences تحقیقی Original article <strong>Study objectives:</strong> Rheumatoid arthritis (RA) is a common chronic and systemic autoimmune disease, characterized by inflammation and the destruction of the joints. It is well known that CD4+ T cells play a major role in the pathogenesis of RA. Expanded subpopulations of CD4+ T cells have been reported in RA patients. Here, we investigated the expression of PD-1 on subsets of CD4+ T cells (CD4+CD28- and CD4+CD28+ T cells) in the peripheral blood (PB) and synovial fluid (SF) of patients with RA.<br> <strong>Methods: </strong>A total of 42 RA patients, including 10 newly diagnosed (ND) and 32 relapsed (RL) cases and also 20 healthy controls were enrolled. Phenotypic characterization subsets of CD4+ T cells were evaluated by flow cytometry, using fluorescence conjugated specific human monoclonal antibodies.<br> <strong>Results:</strong> The frequency of CD4+CD28+ T cells was significantly increased in SF versus PB in ND and RL patients. In contrast, the percentage of CD4+CD28- T cells was elevated in PB of ND and RL patients comparison to SF. Expression of PD-1 on CD4+CD28+ and CD4+CD28- T cells in PB of ND and RL patients was significantly higher than the healthy controls. Furthermore, PD-1 expression on CD4+CD28+ and CD4+CD28- T cells in SF versus PB of RL patients were significant increased.<br> <strong>Conclusion: </strong>These data suggest that CD4+ T cells subsets in RA patients were resistance to PD-1 mediated effects and PD-1 has insufficient ability to suppression of CD4+T cells. CD4+CD28+ T cells,CD4+CD28- T cells,CXCR3,PD-1,Rheumatoid Arthritis 61 70 http://goums.ac.ir/jorjanijournal/browse.php?a_code=A-10-551-1&slc_lang=en&sid=1 faezeh ajam faezeh_ajam@yahoo.com 10031947532846005317 10031947532846005317 No Student Research Committee, Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran Mehrdad Aghaei mehrdadaghaie@yahoo.com 10031947532846005318 10031947532846005318 No Golestan Rheumatology Research Center (GRRC), Golestan University of Medical Sciences, Gorgan, Iran Saeed Mohammadi s.mohammadi@goums.ac.ir 10031947532846005319 10031947532846005319 No Stem Cell Research Center, Golestan University of Medical Sciences, Gorgan, Iran Mohsen Saeedi saeedi.m50@gmail.com 10031947532846005320 10031947532846005320 No Stem Cell Research Center, Golestan University of Medical Sciences, Gorgan, Iran Nasser Behnampour behnampour@yahoo.com 10031947532846005321 10031947532846005321 No Public Health Department, Faculty of Health, Golestan University of Medical Sciences, Gorgan, Iran Ali Memarian alimemarian@goums.ac.ir 10031947532846005322 10031947532846005322 Yes Golestan Rheumatology Research Center (GRRC), Golestan University of Medical Sciences, Gorgan, IranGolestan Research Center of Gastroenterology and Hepatology, Golestan University of Medical Sciences, Gorgan, Iran