CD4 and rheumatoid arthritis: The CD4+CD25+Foxp3+ Treg cells [6.18 (5.03–13.34) % vs. 2.62 (1.58–5.36) %; p < 0.01] and CD4+CD25−Foxp3+ T cells [6.19 (3.94–8.12) % vs. 3.20 (1.85–5.51) %; p < 0.01] produced more IL-17A in the RA group than in the HC group.