CD4 and rheumatoid arthritis: Further analysis showed significant differences among the percentages of CD4+CD28−OX40+ T cells in PB samples of patients with Re-RA (5.94 ± 2.24%), Lo-RA (9.68 ± 2.31%, P = 0.001), Mo-RA (11.14 ± 3.12%, P < 0.001), and Hi-RA (12.65 ± 4.47%, P < 0.001) (all vs Re-RA) (Fig. 3b).