CD4 and rheumatoid arthritis: Finally, two studies (a, ac) in which Tregs were defined as “CD25 and FOXP3 double positive” were selected for meta-analysis (REM 3.27, [0.40 to 6.14]) (Fig 5B); the results revealed that the proportion of Tregs among CD4+ T cells in SF was significantly higher than that in PB of RA patients.