In both RA and healthy control, after 72 hours stimulation, the levels of RANKL, TNF-α, IL-17, IL-6, and IL-4 in the anti-CD3/CD28 group significantly enhanced compared with the vehicle control group (P < 0.05; Table 2); although the level of OPG and RANKL/OPG in anti-CD3/CD28 group showed a little increase, the differences did not reach significance (P > 0.05, Table 2). Here, CD28 is linked to rheumatoid arthritis.