Influence of KIR genes and their HLA ligands in the pathogenesis of leprosy in a hyperendemic population of Rondonópolis, Southern Brazil

Background: The objective of this study was to investigate the association between KIR genes and the immunopathogenesis of leprosy. Methods: The types of KIR and HLA genes were evaluated by PCR-SSOP-Luminex in 408 patients with leprosy and 413 healthy individuals. Statistical analysis was performed using the Chi-square or Fisher’s exact test and stepwise multivariate analysis. Results: There was a higher frequency of activating KIR genes (KIR2DS1, 2DS2 and 3DS1) together with their HLA ligands in the tuberculoid (TT) group as compared to the lepromatous leprosy (LL) group. KIR2DL2/2DL2-C1 was more frequent in the patient, TT and LL groups than in the control group. Borderline patients presented a higher frequency of inhibitory pairs when compared to the control group, and a higher frequency of activating pairs as compared to the LL group. Multivariate analysis confirmed the associations and demonstrated that being a female is a protective factor against the development of the disease per se and the more severe clinical form. Conclusions: This study showed that activating and inhibitory KIR genes may influence the development of leprosy – in particular, activating genes may protect against the more aggressive form of the disease – thereby demonstrating the role of NK cells in the immunopathology of the disease