HLA-DM polymorphisms do not associate with multiple sclerosis: an association study with analysis of myelin basic protein T cell specificity.

The MHC region on 6p harbors at least one susceptibility gene for multiple sclerosis (MS). Within this region, HLA-DM loci are of interest being involved in class II antigen processing. We investigated the association of HLA-DM polymorphisms with MS. Sixty-three patients with MS and 46 healthy controls from continental Italy were typed for HLA-DM polymorphisms and HLA-DRB1 alleles. Besides, among the donors characterized for the DM polymorphisms, we considered 6 MS patients previously studied for the fine specificity of their MBP-specific T lymphocyte lines (TLL). The frequencies of allelic variants at the DMA and DMB loci were similar between MS patients and controls, even when HLA-DRB1*1501 positive and negative donors were analyzed separately. Patients with predominant responses to different MBP epitopes did not differ for their HLA-DM haplotype while patients with predominant responses to the same MBP epitope could present different HLA-DM haplotypes. HLA-DM polymorphisms do not associate with MS and may not affect specific patterns of T cell responses to MBP.