In the present study, we demonstrated that the numbers of Mon2 monocytes increased during the active phase of RA in the presence of activated platelets and the consequent MPA formation, and that anti-CD147 blocking antibody group, which we found to abrogate MPA formation and phenotypic shifts, appears to be induced by contact co-culturing of platelets and monocytes. The gene discussed is BSG; the disease is rheumatoid arthritis.