Background: To establish the relation between class I and II HLA antigens, systemic lupus erythematosus (SLE), autoantibodies production, and clinical manifestations in the south of Spain (Málaga).
Methods: In a regional hospital we undertook a case-control study with a consecutive sample of 104 patients with SLE who fulfilled at least 4 criteria of ARA. Three hundred and twenty-eight local controls with no apparent pathology were included for comparison. We evaluated clinical and analytical aspects about multisystem autoimmune disease. HLA typing was serologically determined.
Results: Univariate analysis showed a relation between SLE and the specificities B8 (21% of patients vs 10% of controls, p = 0.005; RR = 2.3), DR3 (36% vs 20%, p = 0.0006; RR = 2.5), DRw52 (69% vs 49%, p = 0.001; RR = 2.3), and DQ2 (49% vs 36%, p = 0.0150; RR = 1.7). However, in logistic regression multivariate analysis, there was a confounding effect between DR3 and DRw52, and it could be that only this specificity, HLA-DRw52 (RR = 2.0; 95% CI: 1.1-4.0), and of lesser degree B8 (RR = 1.9; 95% CI: 0.9-4.4), are really associated with SLE. Also, in multivariate analysis, DR6 showed a negative association (5% vs 25%, p = 0.011; RR = 4.2; 95% CI: 1.5-17.2) with anti-U1RNP, while DRw52 showed a negative association with IgG-aCL (50% vs 85%, p = 0.019; RR = 0.21; 95% CI: 0.06-0.76). Furthermore, DQ2/DQ6 showed positive association with anti-SSA/Ro antibodies (50% vs 24%; p = 0.046; RR = 3.0; 95% CI: 1.0-9.0). There were also several associations between clinical manifestations and HLA. The specificities DR and DRw53 were almost always risk factors, but only DR5 was a protector for renal lesion. DRw52 and DQ specificities were always protectors when they were associated with some clinical manifestations. Isolated DR3 antigen, is not associated with any of the above-mentioned manifestations.
Conclusions: The previously described relation between SLE and the antigen DR3 is confirmed, but this association could be a result of the presence of DRw52 specificity in patients, that is in linkage disequilibrium with DR3.