KIR: Killer cell Immunoglobulin-like Receptor, MHC class I receptors expressed by NK cells and a subpopulation of T cells.
The human leukocyte receptor complex (LCR) is a genetic region of at least 1MB on chromosome 19 at 19q13.4 which contains genes encoding the KIR responsible for inhibiting the innate cytotoxic activity of NK lymphocytes.
The LILR/ILT/LIR  which have
The KIR and LILR/ILT/LIR protein families are structurally and functionally comparable. Both:
Despite these similarities, the KIR and LILR/ILT/LIR receptors have distinct functional characteristics. Whereas most KIR recognize discrete polymorphic epitopes within the G-ALPHA-1 of HLA class I, only the LILR1/ILT2 and LILR2/ILT4 receptors have been demonstrated to bind to a variety of HLA class I ligands. The binding of LILR1/ILT2 is probably mediated via a site in the conserved C-LIKE-DOMAIN of the HLA class I.
Mice do not possess KIR genes, but a locus on mouse chromosome 7 (syntenic to human 19q13) contains PIR genes with sequence homology to the human ILT/LIR genes.