In addition, a unique phenotype of CD8αα+TCRαβ+Qa-1 restricted Treg cells (in mice) and HLA-E in humans, expressing surface molecules typical of NK cells, has been demonstrated (35), as well as the recent discovery of a CD8+KIR+ Treg cell subpopulation, which appears to play an important role in the maintenance of peripheral tolerance in the context of antigen-specific viral infections and its relationship to autoimmunity (179). This evidence concerns the gene HLA-E and viral infectious disease.