Differential contribution of HLA-DR, DQ, and TAP2 alleles to systemic lupus erythematosus susceptibility in Spanish patients: role of TAP2*01 alleles in Ro autoantibody production.

OBJECTIVE

To study the influence MHC class II and TAP2 alleles exert on systemic lupus erythematosus (SLE) susceptibility and on the clinical and serological manifestations of the disease, in a cohort of Spanish patients.

METHODS

HLA-DR serological typing and HLA-DQA, DQB, and TAP2 DNA sequence specific oligotyping, were carried out in 85 unrelated Spanish SLE patients and 186 healthy controls. Autoantibodies detection was carried out by indirect immunofluorescence and counter immunoelectrophoresis.

RESULTS

Total SLE group: the frequency of HLA-DR3 and HLA-DQA10501 is significantly increased in this group (pc < 0.005, delta = 0.34 and pc < 0.005, delta = 0.45, respectively) although the highest delta value (delta = 0.87) is obtained when the TAP201 alleles are considered. No DQB allele shows significant deviation from the control group. Renal damage: it mainly occurs in HLA-DR3 patients (pc < 0.0005 and delta = 0.72). HLA-DQA10501 (p < 0.05, delta = 0.57 and DQB10201 (pc NS, delta = 0.56) are weaker susceptibility factors. Ro+ (but not LA) group: this autoantibody response is associated with TAP201 alleles in homozygosity (p < 0.05, delta = 0.81). R0/La+ group: it has a different genetic background as HLA-DQA10501 (delta = 1) and HLA-DQB1*0201 (delta = 1) are the main susceptibility factors.

CONCLUSIONS

A differential association between HLA-DR, DQA1, and DQB1 alleles and SLE or its clinical and serological manifestations are found. Furthermore, the associations are different to the ones reported in other ethnic groups. Finally, TAP201 group of alleles are associated with the highest susceptibility to SLE (higher than HLA-DR3) and may influence Ro (but not La) autoantibodies production, whereas HLA-DQA10501 and DQB1*0201 mediates concomitant Ro and La productions.