Analysis of autoimmune disorders has revealed that CD8 T regulatory cells (CD8 Tregs) inhibit pathogenic responses through recognition of self-peptides associated with MHC class Ia or class Ib (MHC-E: mouse Qa-1 and human HLA-E) (2, 6) expressed by target CD4+ T helper cells. This evidence concerns the gene HLA-E and autoimmune disease.