CD4 and rheumatoid arthritis: The expression levels of CTLA4 [36.36 (28.29–42.95) % vs. 56.69 (46.61–67.39) %; p < 0.01] and GITR [51.52 (32.35–61.85) % vs. 61.40 (56.84–70.87) %; p < 0.05] in CD4+CD25−Foxp3+ T cells were lower in RA patients than in HCs.