Antibodies to type II collagen and their association with HLA DR1 alleles in Japanese patients with rheumatoid arthritis

To investigate whether immunological responses to type II collagen (CII) play an important role in the patho- genesis of rheumatoid arthritis (RA), the presence of anti- CII antibodies was examined by enzyme immunoassay in 130 Japanese patients with RA, 10 systemic lupus ery- thematosus (SLE) patients, and 30 healthy subjects. In addition, the HLA-DRB1 genes of 40 RA patients were determined, and their association with positive findings of anti-CII antibodies was examined. A significantly high frequency of positive findings of anti-CII antibodies was detected in sera from RA patients (19%, P 0.05) in com- parison with that in sera from healthy subjects (3%). High frequencies of DRB1*0405 and 0101 alleles were observed in the 40 RA patients examined (40.0% and 30.0%, respec- tively). Patients with DRB1*0101 had a significantly higher rate of positive findings of anti-CII antibodies than those without DRB1*0101 (66.7% and 28.6%, respectively, P 0.05). No such association was observed for DRB1*0405. From these findings, we suggest that immunological re- sponses to CII may play an important role in the develop- ment of arthritis in some RA patients.