Strong association of HLA-DR4 with benign IgA nephropathy.

103 adult patients with biopsy-proved IgA nephropathy were typed for HLA-A and HLA-B antigens and 80 of these cases were typed for HLA-DR antigens. A significant association with HLA-DR4 was clearly noted (pc less than 0.04). The high phenotype frequency (PF) of BW35 was observed in the patients, but not statistically significant (pc less than 0.2). Two groups, the stable group and progressive group, were selected from all patients according to their clinical courses. The PF of HLA-DR4 was significantly higher in the stable group than the progressive group (pc = 0.005). The PF of BW35 was also higher in the stable group, but this difference was not statistically significant (pc = 0.6). The frequency of the combination of HLA-BW35 and DR4 increased significantly as compared to that in the control group. Further, the patients who had both of these antigens showed favorable courses. These results suggest that the HLA-DR4 antigen, especially a combination of HLA-BW35 and DR4 antigens are related to the occurrence of benign IgA nephropathy.