Association between HLA class II antigens and primary antiphospholipid syndrome from the south of Spain.

Recent studies have suggested an association between primary antiphospholipid syndrome (PAPS), antiphospholipid antibodies and some major histocompatibility complex (MHC) antigens. We have studied the relationship between MHC class II antigens and PAPS in 19 patients from the south of Spain. Univariant analysis showed an association between PAPS and HLA-DQ7 (47% vs 25%l P = 0.3), DR4 (32% vs 16%; P = 0.08) and DQ3 (63% vs 39%; P = 0.04). However, multivariant analysis confirmed the association with DQ7 (RR = 2.5; CI 80%: 1.3-4.7) and DR4 (RR = 2.2; CI 80%: 1.1-4.4) but not with DQ3. When we introduced DRw53 into this analysis, we noticed a DR4 confounding effect, with DQ7 (RR = 3.1; CI 80%: 1.7-5.8) and Drw53 (RR = 2.3; CI 80%: 1.2-4.4) remaining as the most important HLA antigens related to PAPS. In conclusion, in PAPS patients from the South of Spain, HLA-DQ7 antigen showed the highest relative risk for PAPS, followed by DRw53.