In this work, we compared thebinding of the encephalitogenic fragment of the myelin basic protein (MBP) totwo HLA-DR complexes that provide protection against and predisposition to MS:HLA-DR1 (HLA-DRB1*0101) and HLA-DR15(HLA-DRB1*1501), respectively. This evidence concerns the gene HLA-DRB1 and myeloid sarcoma.