Human autoantibodies against the 70‐kd polypeptide of u1 small nuclear rnp are associated with hla‐dr4 among connective tissue disease patients

Serum samples from patients with connective tissue disease (CTD) were characterized using a recently developed enzyme-linked immunosorbent assay for reactivity with individual specific polypeptides of U1 small nuclear ribonucleoproteins, including the U1-70-kd protein. The distribution of HLA antigens was compared in CTD patients with and in those without anti-U1-70-kd autoantibodies and in normal controls. The frequencies of HLA-DR4 and HLA-DRw53 were increased among the anti-U1-70-kd autoantibody positive CTD group compared with the frequencies in anti-U1-70-kd autoantibody negative systemic lupus erythematosus patients and compared with normal controls. We conclude that the presence of autoantibodies reactive with the anti-U1-70-kd protein antigen is associated with HLA-DR4 and HLA-DRw53.