RESUMEN
BACKGROUND AND OBJECTIVE: The HLA-DRB1*15 allele is consistently associated with multiple sclerosis (MS) susceptibility in most studied populations. This study investigated the association between HLA-DRB1 alleles and the presence of oligoclonal immunoglobulin G bands (OCB) in the cerebrospinal fluid (CSF) in a Spanish population with MS. METHODS: The HLA-DRB1 typing was performed in 268 patients with sporadic MS and the detection of OCB in CSF. HLA-DRB1 allelic frequencies were compared between OCB-positive and OCB-negative patients, and both groups were also compared with 1088 unrelated healthy controls. Moreover, we correlated the various HLA-DRB1 genotypes, considering all the combinations of both parental alleles found with the presence or absence of OCB. RESULTS: We found 206 OCB-positive and 62 OCB-negative patients. The HLA-DRB1*15 allele in OCB-positive patients had a higher frequency when compared with OCB-negative patients (39.3% in OCB-positive vs. 16.1% in OCB-negative, OR = 1.38 95% CI = 1.18-1.61, P < 0.001). The other alleles did not show differences. When we compared with controls, the HLA-DRB1*15 allele was associated with the disease only in the OCB-positive patients group. None of the 55 genotypes found showed any association with the presence or absence of OCB. CONCLUSIONS: HLA-DRB1*15 allele is associated with OCB-positive patients with MS when studying a Spanish MS population.