OBJECTIVETo investigate the relationships of polymorphisms of interleukin-2 (IL-2) gene to the susceptibility of chronic hepatitis B, and to analyze the frequencies of IL-2 gene polymorphisms and the HBV-DNA copies in patients with chronic hepatitis B.

METHODSTwo single nucleotide polymorphisms of IL-2 gene promoter -385T/G and +114T/G at exon one were analyzed in 155 patients with chronic hepatitis B and in 170 age- and sex-matched controls from a Chinese population. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) strategy and DNA sequencing were used, and the serum HBV DNA in these patients was determined by real-time PCR.

RESULTSThere were no differences in the distributions of IL-2 gene +114T/G polymorphism in the patient group and the controls, but their IL-2 gene -385T/G polymorphisms were significantly different (P less than 0.05). The relative risk of being chronic hepatitis B victims with T allele was 1.490 times of those with G allele (OR=1.490, 95% CI: 1.085-2.046). The association between the genotype of IL-2 gene polymorphisms and HBV-DNA copies showed that the frequency of -385G allele carriers in high HBV-DNA copy group was closer than that in low HBV-DNA copy group (chi2=6.051, P=0.014).

CONCLUSIONSIL-2 gene -385T/G polymorphism is associated with chronic hepatitis B and G allele is an important genetic susceptibility gene for chronic hepatitis B. In IL-2 gene -385G allele carriers the risk of increasing HBV-DNA copies may be related to the pathogenesis of chronic hepatitis B.