KIR: diverse, rapidly evolving receptors of innate and adaptive immunity

Annu Rev Immunol. 2002;20:217-51. doi: 10.1146/annurev.immunol.20.092501.134942. Epub 2001 Oct 4.


KIR genes have evolved in primates to generate a diverse family of receptors with unique structures that enable them to recognize MHC-class I molecules with locus and allele-specificity. Their combinatorial expression creates a repertoire of NK cells that surveys the expression of almost every MHC molecule independently, thus antagonizing the spread of pathogens and tumors that subvert innate and adaptive defense by selectively downregulating certain MHC class I molecules. The genes encoding KIR that recognize classical MHC molecules have diversified rapidly in human and primates; this contrasts with conservation of immunoglobulin- and lectin-like receptors for nonclassical MHC molecules. As a result of the variable KIR-gene content in the genome and the polymorphism of the HLA system, dissimilar numbers and qualities of KIR:HLA pairs function in different humans. This diversity likely contributes variability to the function of NK cells and T-lymphocytes by modulating innate and adaptive immune responses to specific challenges.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Alleles
  • Amino Acid Sequence
  • Animals
  • Biological Evolution
  • Gene Expression
  • Genetic Variation
  • HLA Antigens / metabolism
  • Haplotypes
  • Histocompatibility Antigens Class I / metabolism
  • Humans
  • Killer Cells, Natural / immunology
  • Molecular Sequence Data
  • Multigene Family
  • Phylogeny
  • Polymorphism, Genetic
  • Receptors, Immunologic / chemistry
  • Receptors, Immunologic / genetics*
  • Receptors, Immunologic / metabolism*
  • Receptors, KIR
  • Sequence Homology, Amino Acid


  • HLA Antigens
  • Histocompatibility Antigens Class I
  • Receptors, Immunologic
  • Receptors, KIR