Combination of KIR 2DL2 and HLA-C1 (Asn⁸⁰) confers susceptibility to type 1 diabetes in Latvians

Killer immunoglobulin-like receptors (KIRs) are known to modulate natural killer (NK) and NK T-cell function by interacting with human leucocyte antigen (HLA) class I ligands on target cells. The aim of our study was to investigate the influence of KIR2D genes with their HLA-C ligands in susceptibility to type 1 diabetes. A total of 98 type 1 diabetes patients and 70 healthy subjects from Latvia were typed for KIR genes and HLA-C ligands using polymerase chain reaction-based genotyping. The HLA C1+/C2+ combination was positively, and C1-/C2+ combination was negatively, associated with type 1 diabetes. Stratification analysis of KIR/HLA-C ligand combinations showed 2DL2+/C1+, 2DL3+/C1+, and 2DS2+ /C1+ to be positively, and 2DL2-/C1- and 2DS2-/ C1- to be negatively, associated. The presence of 2DL2-HLA-C1 in the absence of 2DS1, 2DS2 confers maximum susceptibility. Absence of 2DL2 and HLA-C1 along with absence of 2DS1 and 2DS2 confer maximum protection. A hypothetical model of KIR/ligand combinations on immune responses and type 1 diabetes susceptibility is proposed. Our results suggest that a combination KIR2DL2- HLA-C1 plays a critical role in susceptibility or protection in Latvians against type 1 diabetes.