Functions of nonclassical MHC and non-MHC-encoded class I molecules.
Fascinating recent discoveries have focused attention on the nonclassical class I molecules. They can exert their function at most levels of the immune response, being part of both innate and adaptive immune systems. They not only have specialized antigen-presentation functions but also play important immunoregulatory roles: HLA-E regulates natural killer cells by interacting with CD94/NKG2 receptors; the MIC (MHC class I chain related) glycoproteins appear crucial to the activation of gammadelta T cells in the gastrointestinal epithelium; HLA-G may play a role in controlling the immune response to the fetus; and CD1 molecules are important in defense against bacterial infections, as well as in the development and regulation of a subset of NKT cells expressing a highly restricted TCR repertoire; however not all nonclassical class I molecules have an immunological function, as demonstrated by HFE which is implicated in iron metabolism.
Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK. vbraud@worf.molbiol.ox.ac.uk.
V M
VM
Braud
D S
DS
Allan
A J
AJ
McMichael
D000818:Animals; D018949:Antigens, CD1 / Q000502:physiology; D006680:HLA Antigens / Q000502:physiology; D059951:HLA-G Antigens; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I / Q000502:physiology*; D006801:Humans; D007109:Immunity; D008565:Membrane Proteins; D000097625:HLA-E Antigens
D018949:Antigens, CD1; D006680:HLA Antigens; D059951:HLA-G Antigens; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D000097625:HLA-E Antigens; C103673:HFE protein, human; C099187:MHC class I-related chain A; C098080:MICB antigen; C032907:Q surface antigens