Development of a novel multiplex PCR assay to detect functional subtypes of KIR3DL1 alleles.

Among NK cell receptor-ligand partnerships, KIR3DL1 and HLA-Bw4 demonstrate the greatest diversity; permutations of their allelic combinations titrate NK reactivity. Balancing selection has maintained distinct subtypes of KIR3DL1 alleles in global populations, implying that each may provide unique fitness advantages and variably influence disease processes. Though approaches exist for determining HLA-B allotypes, practical methods for identifying KIR3DL1 alleles are lacking. We have developed a PCR-based approach that identifies functional subtypes of KIR3DL1 alleles; it is suitable for research and may have clinical application. Six allele subsets were identified based on expression characteristics of the eleven most common KIR3DL1 alleles represented in reported populations. The remaining 62 low-frequency alleles were distributed into these groups based on sequence homology to coding regions. Subtype-specific SNPs were found in exons 3, 4, and 7, and used as priming sites for five multiplex PCR reactions. Genomic DNA derived from 175 unrelated donors and 52 related individuals from 6 families demonstrated >99.5% concordance between sequence-based typing and our novel approach. Finally, PCR-based typing accurately predicted NK phenotypes obtained by flow cytometry after staining with DX9 and Z27 monoclonal antibodies. This novel approach facilitates high-throughput analysis of KIR3DL1 allotypes to enable a broader understanding of KIR3DL1 and HLA-Bw4 interaction in health and disease.