Mice transplanted with PBMC from HLA-DRB1*15-positive (DR15) MS patients uniquely developed spontaneous hCD8+ T cell lesions in the spinal cord gray matter and brainstem, and prominent brain white and gray matter lesions with mixed hCD4/hCD8 T cells in mice immunized for EAE with myelin peptides. This evidence concerns the gene HLA-DRB1 and myeloid sarcoma.