JKAP-knockdown BMSC-exosomes increased the percentage of RA CD4+IL-17A + cells (p < 0.05) and the level of IL-17A (p < 0.05) (Figures 2F–2H), but did not affect the percentage of RA CD25+Foxp3+ cells (p > 0.05) and inhibited the level of IL-10 (p < 0.05) compared to Scramble BMSC-exosomes (Figures 2I–2K). Here, CD4 is linked to rheumatoid arthritis.