Genotyping of human killer-cell immunoglobulin-like receptor genes by polymerase chain reaction with sequence-specific primers: an update.

Killer-cell Immunoglobulin-like Receptors (KIR) help human natural killer (NK) cells counteract infections by pathogens that evade the immune system by inducing down-regulation of HLA class I molecules in infected cells. KIRs are structural and functionally diverse receptors encoded by a family of polymorphic genes. The most extreme aspect of KIR polymorphism is the varying content of KIR-genes in the genome of different individuals, as first demonstrated by KIR genotyping using the PCR-SSP method. Knowledge on the KIR-gene family has been recently expanded by the identification of new genes, pseudogenes and multiple gene variants, several of which escaped detection by the original genotyping technique. We present here an upgraded PCR-SSP method for KIR genotyping that integrates recent achievements in the research of the diversity of this gene family. Our method permits detection of all known KIR genes and pseudogenes in a 16-reaction set. Furthermore, an additional set of six reactions permits subtyping of KIR2DL5 variants, each of which shows well-differentiated functional and genetic features.