An increased frequency of NK cell receptor and HLA-C group 1 combinations in early-onset type 1 diabetes.

Aims/hypothesis: Natural killer (NK) cells serve as primary immune surveillance and are partially regulated by combinations of killer immunoglobulin-like receptor (KIR) genes and their HLA class I ligands. Alterations in NK cell activity have been associated with type 1 diabetes. The aim of this study was to determine whether KIR-HLA class I gene frequency: (1) is altered in a current population with type 1 diabetes compared with healthy controls; and (2) has changed over the half century in which the incidence of type 1 diabetes has increased rapidly. Methods: KIR-HLA class I gene frequencies were compared in 551 individuals diagnosed with type 1 diabetes ≤15 years of age (394 in a current cohort and 157 from the historical 'Golden Years' cohort) and 168 healthy controls. The overall balance of activation and inhibition was analysed using KIR-HLA genotype models. Results: Children with type 1 diabetes who were positive for KIR2DS2/KIR2DL2 and KIR2DL3 were more often homozygous for HLA-C group 1 and this effect was strongest in children diagnosed with diabetes before the age of 5 years ( p = 0.003, corrected p [ p] = 0.012) and ( p = 0.001, p = 0.004), respectively. Children with type 1 diabetes have fewer inhibitory KIRs with their corresponding ligands compared with healthy controls ( p = 1.9 × 10). This pattern of NK activation has not changed significantly in individuals with type 1 diabetes over the last half century. Conclusions/interpretation: Activating combinations of KIR-HLA genes are more frequent in young children with type 1 diabetes diagnosed in the first 5 years of life, suggesting that NK cell responses may be altered in this group. [ABSTRACT FROM AUTHOR]