A novel family of Ig-like receptors for HLA class I molecules that modulate function of lymphoid and myeloid cells.
We review what is presently known about structure, cellular distribution, biochemical characteristics, and function of a new family of human cell-surface receptors referred to as immunoglobulin-like transcripts (ILTs), leukocyte Ig-like receptors (LIRs), or monocyte/macrophage Ig-like receptors (MIRs). These receptors are genetically, structurally, and functionally related to a group of natural killer (NK) cell receptors for HLA class I molecules known as killer cell Ig-like receptors (KIRs). Distinct ILT/LIR/MIR isotypes are differentially expressed on lymphocytes, monocytes, macrophages, dendritic cells, and granulocytes; at least some of them recognize HLA class I molecules. Whereas some isotypes either inhibit or induce cell activation, others may be secreted as soluble receptors. ILT/LIR/MIR receptors may allow all immune cells to monitor class I expression on other cells and to respond in its absence, just as NK cells do. In addition, they may contribute to homeostasis by establishing activation thresholds that can be overcome only by relevant triggering stimuli and not by bystander cells.
Colonna
M
M
Basel Institute for Immunology, Switzerland.
Nakajima
H
H
Navarro
F
F
López-Botet
M
M
D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD; D003602:Cytotoxicity, Immunologic; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D006706:Homeostasis; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007694:Killer Cells, Natural / Q000276:immunology; D000075362:Leukocyte Immunoglobulin-like Receptor B1; D007962:Leukocytes / Q000276:immunology* / Q000378:metabolism; D008221:Lymphoid Tissue / Q000276:immunology*; D046911:Macromolecular Substances; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D009000:Monocytes / Q000276:immunology / Q000378:metabolism; D005810:Multigene Family; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D017452:Receptors, IgG / Q000378:metabolism; D011971:Receptors, Immunologic / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000276:immunology* / Q000502:physiology*; D054340:Receptors, KIR; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D015395:Histocompatibility Antigens Class I; D047908:Intracellular Signaling Peptides and Proteins; C105298:LILRA2 protein, human; C105299:LILRB1 protein, human; D000075362:Leukocyte Immunoglobulin-like Receptor B1; D046911:Macromolecular Substances; D017452:Receptors, IgG; D011971:Receptors, Immunologic; D054340:Receptors, KIR; C119832:neutrophil immunoglobulin-like receptor 1; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases