Cytokine polymorphisms and susceptibility to leprosy / Polimorfismos de citocinas e susceptibilidade à hanseníase

ABSTRACT

Cytokines play a key role in the regulation of the immune response against infectious diseases. In leprosy, the polymorphisms of pro-inflammatory cytokine genes may contribute to host susceptibility to Mycobacterium leprae. The objective of this study was to investigate the association between cytokine gene polymorphisms and BCG protection against leprosy in Brazilian leprosy cases and controls. DNA samples were obtained from 46 patients with leprosy and 83 healthy controls (not leprosy contacts). All genotyping (TNF alpha, IFN gamma, IL-6, IL-10 and TGF beta) measurements were taken using sequence-specific primers (SSP) - PCR. When compared to the healthy controls, no significant associations were observed between the cytokine gene polymorphisms studied and their susceptibility to leprosy. The most frequent genotypes in this population were TNF alpha ?G? allele and G/G genotype at position -308, ?A? allele of IFN gamma at position +874, G allele in the IL-6 at position -174, G allele (codon 25) and T/C-G/G genotype in TGF beta, and ?A? allele in IL-10 at position -1082. For those individuals that had a BCG scar, the TGF beta and IFN gamma genotype polymorphisms did not show difference among leprosy patients compared to healthy controls. Polymorphisms of the cytokine genes studied were not associated with an increased occurrence of leprosy.