IL-18 promoter -137G/C polymorphism correlates with chronic hepatitis B and affects the expression of interleukins.

The relationship between the interleukin (IL)-18 promoter -137G/C polymorphism and plasma levels of IL-18, IL-12, IL-4, and IFN-γ in chronic hepatitis B (CHB) patients and healthy subjects was investigated. The polymorphism was genotyped by a ligase detection reaction-PCR (LDR-PCR), while the cytokines were assayed by ELISA. Compared with healthy subjects, CHB patients exhibited an increased frequency of the G allele, GG genotype and increased IL-4 levels, but decreased levels of IL-18, IL-12, and IFN-γ. A positive correlation for IL-18 ~ IL-12 ~ IFN-γ and a negative correlation for IL-18 ~ IL-4 were found. We conclude that the IL-18 promoter -137G polymorphisms correlated with CHB infection and influenced the expression of IL-18. The studied interleukins represent an immunomodulatory network that plays important roles in host immune responses to CHB infection.