Distribution of natural killer cell immunoglobulin-like receptor sequencesin three ethnic groups

Killer cell immunoglobulin-like receptors (KIRs) are members of a group of molecules that specifically recognize HLA class I ligands and are found on subsets of human lymphopoetic cells. The number of KIR loci can vary betwee n individuals, resulting in a heterogeneous array of possible KIR genes. Th e range of observed profiles has been explained by the occurrence of two ha plotype families termed A and B which can be distinguished on the basis of certain KIR sequences. Here we attempted to determine whether the frequenci es of putative KIR loci and the two haplotype groups vary in three ethnical ly defined, healthy, and unrelated control populations, namely UK Cancasoid (n=136), Palestinian (n=105) and Thai (n=119). We molecularly typed genomi c DNA for the presence of 12 putative KIR loci, KIR2DL1, KIR2DL2, KIR2DL3, KIR2DL4, KIR3DL1, KIR3DL2, KIR2DS1, KIR2DS2, KIR2DS3, KIR2DS4, KIR2DS5, and KIR3DS1, using modified PCR sequence-specific primers. The patterns of KIR locus frequencies combined with the similar linkage disequilibrium values suggest that there was a distinction in the distribution of the two broad h aplotype groups between the populations studied. The A haplotype was always the most prevalent, but the ratio of A to B varied between populations. Th e frequency of B haplotype was highest in the Palestinians and lowest in th e Thais (P-c<0.0001).