When autoimmune responses to CII and oxPTM-CII were analyzed according to HLA-DRB1 subtypes, we found that ROS-CII but not native CII autoimmunity was restricted to the HLA Shared Epitope (SE) containing DRB1*04 alleles (112), known to confer the greatest risk for developing RA (OR 3-13) (113). Here, HLA-DRB1 is linked to rheumatoid arthritis.