Population frequencies and putative haplotypes of the killer cell immunoglobulin-like receptor sequences and evidence for recombination.

Background: The killer cell immunoglobulin-like receptors (KIR) are a family of receptors expressed on natural killer (NK) cells and some T cells. Class I HLA molecules on target cells are the ligands for the KIR receptors. The number of KIR genes has been reported to vary between individuals, resulting in different KIR haplotypes. There is little published data on the frequency of each KIR gene and the linkage disequilibrium between the genes. Because there is evidence that NK cells may be involved in bone marrow transplant rejection, we have determined the KIR gene frequencies and possible haplotypic arrangements by linkage disequilibrium analysis in an Australian population.

Methods: Controls, patients with leukemia, and unrelated bone marrow donor-recipient pairs were typed for the presence of 11 KIR genes by polymerase chain reaction-sequence specific priming.

Results: Ninety percent of the population was found to have a sufficient number and variety of KIR genes to detect any mismatch of HLA-A, -B, and -C alleles on NK target cells. The 11 KIR genes could be divided into two groups based on linkage disequilibrium between pairs of genes. Evidence for a recombination within the KIR gene complex is presented.

Conclusion: Typing for the presence of particular KIR genes may be indicated for bone marrow donor-recipient pairs for whom a class I HLA mismatch is unavoidable.