Association of interleukin-2 gene variants (positions +114 and −384) and susceptibility to brucellosis in Iranian population

Abstract

Brucella is an obligate intracellular gram negative bacterium and the causative agent of brucellosis. Interleukin-2 (IL-2) is a cytokine involved in cell-mediated immunity response secreted by activated T-cells and considered as the growth factor for T-cells. Previous reports have revealed that gene polymorphisms of cytokines can affect susceptibility to Brucella infection. The goal of this study was to investigate the relationship between IL-2 gene polymorphisms (positions +114 and −384) and susceptibility to brucellosis. A total of 173 brucellosis patients and 75 healthy animal husbandmen who had Brucella infected animals and consumed their contaminated dairy products, as control group, were included in this study. All participants were genotyped for IL-2 gene polymorphisms at positions +114 (G/T) and −384 (G/T), using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). The frequency of TT genotype at the position +114 was significantly higher in the controls, compared with the patients. But, there was no significant difference between the groups regarding TG and GG genotypes as well as T and G alleles. Furthermore, at position −384, the frequencies of G allele and GG genotype were higher in the controls compared with patients, however, they were not significantly different Additionally, TT/TT haplogenotype (+114/−384) was significantly higher in the controls, compared with the patients. Conclusively, it is suggested that the inheritance of TT genotype (position +114) and TT/TT haplogenotype (+114/−384) of IL-2 gene could be considered as one of the genetic factors responsible for resistance to brucellosis.