HLA class II alleles associations of anticardiolipin and anti-β2GPI antibodies in a large series of European patients with systemic lupus erythematosus

The objective of this study was to determine the HLA class II associations of the anticardiolipin (aCL) and anti-beta(2)GPI (a beta(2)GPI) antibodies in a large series of European patients with systemic lupus erythematosus (SLE). A cohort of 577 European SLE patients was enrolled. aCL and a beta(2)GPI were measured by ELISA methods. Molecular typing of HLA-DRB1, DRB3, DRB4, DRB5, DQA1 and DQB1 loci was performed by the polymerase chain reaction-sequence specific oligonucleotide probes (PCR-SSOP) method. aCL of IgG, IgM and IgA isotypes were detected in 22.8%, 14% and 13.9% of patients, respectively. IgG and IgM a beta(2)GPI were detected in 20% of patients, aCL showed positive association with HLA DRB1*04, DRB1*0402, DRB1*0403, DRBI*07, DRB3*0301, DQA1*0201, DQA1*0301, DQB1*0302, and negative association with DQA1*0501, DRB3*0202. a beta(2)GPI showed positive association with DRB1*0402, DRB1*0403, DQB1*0302. DRB1*0402 carried the highest relative risk for the presence of both aCL (RR = 8.1) and a beta(2)GPI (RR = 4.6). Our results confirm the already described associations of aCL with HLA DR4 and DR7, but also demonstrate that, among the alleles at the DRB1*04 locus; the *0402 was most represented both in aCL and in a beta(2)GPI positive patients. In addition, HLA class II associations of a beta(2)GPI are for the first time extensively examined in a large cohort of European SLE patients.