increased expression of pd-1 on cd4+ t cells subsets in rheumatoid arthritis patients

Study objectives: 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. methods: 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. results: 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. conclusion: 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.