Killer Cell Immunoglobulin-Like Receptor Genes and Their HLA-C Ligands in Hashimoto Thyroiditis in a Chinese Population

OBJECTIVE:Natural killer (NK) cells serve as primary immune surveillance and are partially regulated by combinations of killer immunoglobulin-like receptors (KIR) and their human leukocyte antigen-C (HLA-C) ligands. Alterations in NK cell activity have been associated with Hashimoto thyroiditis (HT). The aim of this study was to determine whether certain KIR/HLA-C genotype combinations play a role in HT pathogenesis.METHODS:The present study enrolled 107 unrelated HT patients and 108 random healthy individuals in a case-control study. Blood was collected for DNA extraction; typing of KIR genes and HLA-C alleles was performed by polymerase chain reaction with sequence specific primers (PCR-SSP), followed by electrophoresis on agarose gels.RESULTS:Among a panel of KIR2D/HLA-C genotype combinations, the frequency of KIR2DS2/HLA-C1 was significantly increased in HT patients compared to controls (33.64% vs. 12.96%, P<.001). To further analyze the precise genotype, we investigated inhibitory or activating KIR/HLA-C gene pairs when their corresponding activating or inhibitory KIR genes were absent in the 2 groups. Only the frequency of KIR2DS2(-)2DL2/3(+)HLA-C1(+) was significantly decreased in HT patients compared to controls (48.60% vs. 70.37%, P = .001).CONCLUSION:Our data suggest that KIR2DS2/HLA-C1 may correlate with HT pathogenesis. On the contrary, the predominance of KIR2DL2/3/HLA-C1 in the absence of KIR2DS2 suggests a potential inhibitory role in HT pathogenesis. In conclusion, our findings may further elucidate the mechanisms underlying the pathogenesis of HT and other autoimmune diseases.ABBREVIATIONS:HLA-C = human leukocyte antigen-C HT = Hashimoto thyroiditis KIR = killer immunoglobulin-like receptor NK = natural killer PCR = polymerase chain reaction.