IL-21R expression on Tfh-like cells in RA patients was substantially augmented compared to HC (6.64% ± 0.97% vs. 3.03% ± 0.40%, P < 0.05; Figure 3c), but this phenomenon was not detected on CXCR5-CD4+T cells (0.62% ± 0.11% vs. 1.00% ± 0.19%, P > 0.05; Figure 3d). Here, CD4 is linked to rheumatoid arthritis.