HLA-DPB1 and systemic lupus erythematosus: In another study, DR4 and DRw53 occurred with increased frequency in patients with primary APS (51), and a study of 577 European SLE patients presenting with anti-CL antibodies found a positive association with DPB1*1501 (P value: 0.005, OR 7.4), and DPB1*2301 (P value: 0.009, OR 3.3).