The role of CD94/NKG2 in innate and adaptive immunity.
CD94/NKG2 is a heterodimer expressed on natural killer (NK) and a small subset of T cells. This receptor varies in function as an inhibitor or activator depending on which isoform of NKG2 is expressed. The ligand for CD94/NKG2 is HLA-E in human and its homolog, Qa1 in mouse, which are both nonclassical class I molecules that bind leader peptides from other class I molecules. Although <5% of CD8 T cells express the receptor in a naïve mouse, its expression is upregulated upon specific recognition of antigen. Similar to NK cells, most CD8 T cells that express high levels of CD94 co-express NKG2A, the inhibitory isoform. The engagement of this receptor can lead to a blocking of cytotoxicity. However, these receptors have also been implicated in the cell survival of both NK and CD8 T cells. The level of CD94 expression is inversely correlated with the level of apoptosis in culture. Thus, CD94/NKG2 receptors may regulate effector functions and cell survival of NK cells and CD8 T cells, thereby playing a crucial role in the innate and adaptive immune response to a pathogen.
Gunturi
Anasuya
A
Center for Immunology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9093, USA.
Berg
Rance E
RE
Forman
James
J
D000818:Animals; D015703:Antigens, CD / Q000276:immunology*; D017209:Apoptosis / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002470:Cell Survival / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular; D007113:Immunity, Innate; D007694:Killer Cells, Natural / Q000276:immunology*; D037181:Lectins, C-Type / Q000276:immunology*; D055654:NK Cell Lectin-Like Receptor Subfamily C; D051920:NK Cell Lectin-Like Receptor Subfamily D; D011971:Receptors, Immunologic / Q000276:immunology*; D055607:Receptors, Natural Killer Cell
D015703:Antigens, CD; C527054:KLRC1 protein, human; C497869:KLRD1 protein, human; C527057:Klrc1 protein, mouse; D037181:Lectins, C-Type; D055654:NK Cell Lectin-Like Receptor Subfamily C; D051920:NK Cell Lectin-Like Receptor Subfamily D; D011971:Receptors, Immunologic; D055607:Receptors, Natural Killer Cell