Mammalian non-classical major histocompatibility complex I and its receptors: Important contexts of gene, evolution, and immunity.

The evolutionary conserved, less‑polymorphic, nonclassical major histocompatibility complex (MHC) class I molecules: Qa‑1 and its human homologue human leukocyte antigen‑E (HLA‑E) along with HLA‑F, G and H cross‑talk with the T‑cell receptors and also interact with natural killer T‑cells and other lymphocytes. Moreover, these nonclassical MHC molecules are known to interact with CD94/NKG2 heterodimeric receptors to induce immune responses and immune regulations. This dual role of Qa‑1/ HLA‑E in terms of innate and adaptive immunity makes them more interesting. This review highlights the new updates of the mammalian nonclassical MHC‑I molecules in terms of their gene organization, evolutionary perspective and their role in immunity.