MHC-I recognition by receptors on myelomonocytic cells: new tricks for old dogs?
Receptors on cytotoxic T lymphocytes and natural killer cells play well-established roles in the immunological response and share a common ligand in the form of MHC-I. We discuss how a variety of MHC-I receptors are also expressed on myelomonocytic cells such as macrophages and dendritic cells. Since myelomonocytic MHC-I receptors recognise a broad range of alleles and MHC-I structures, we propose that their task is to discern expression levels and folding forms of MHC. We describe a model in which these recognition events would regulate bidirectional cross talk between cells of innate and adaptive immune systems to organise an ongoing combined immune response. We discuss how such a model is supported by recent literature and might function in a variety of contexts, including immunoregulation during pregnancy. Our model also offers an alternative explanation of immune dysregulation rather than autoimmunity during HLA-B27-associated spondyloarthropathies and addresses a number of conundrums in this field.
Raine
Tim
T
Department of Pathology, Cambridge University, Cambridge, UK.
Allen
Rachel
R
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D004194:Disease; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology* / Q000378:metabolism*; D008264:Macrophages / Q000276:immunology / Q000378:metabolism; D018448:Models, Immunological; D010920:Placenta / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism
D015395:Histocompatibility Antigens Class I