Rheumatoid arthritis (RA) is a chronic autoimmune disease that is characterized by destructive polyarthritis. The patients with RA will be changed to be disable if they can't been diagnosed and cured in early phase of RA, however the etiologic agent of RA remains unclear now. There is some evidences that type II collagen (CII) might act as an autoantigen of correlating with RA. So, we had extracted and purified human CII,detected the positive frequencies of CII -reactive T cells and the positive frequencies...