Polymorphisms of IL-1B, IL-1RN, IL-2, IL-4, IL-6, IL-10, and IFN-γ genes in the Korean population

Cytokines play a crucial role in regulating the immune and inflammatory responses. The collective influence of several cytokines can regulate immune responses as complex as those underlying allograft rejections or autoimmune diseases. Polymorphisms in the regulatory regions of the cytokine genes may influence their expression. Therefore, the polymorphisms of cytokine genes are potentially important as genetic predictors of the disease susceptibility or clinical outcome. In 311 unrelated healthy Korean individuals, we investigated the polymorphisms of cytokine genes (interleukin-1 [IL-1], IL-2, IL-4, IL-6, IL-10, and interferon-γ [IFN-γ]), which had been previously reported to be associated with a number of immune diseases, transplant complications, and direct or indirect influences on the level of expression and production. And we also compared the results to those published for other populations. The genotype distributions were consistent with the assumption of the Hardy-Weinberg equilibrium, with the exceptions of IL-1B +3954 and IL-6-174 polymorphisms. The polymorphisms examined in this study were almost similar to that observed in Asian populations. There were significant differences of the polymorphisms, except for IL-4 receptor α +1902, between Korean and other populations. Comparing the alleles associated with higher level of expression and production, IL-1B +3954*T, IL-2-330*G, and IL-4-590*T alleles were significantly higher, and IL-1RN*A2, IL-10-1082*G, and IFN-γ*2 alleles were lower in Koreans than other populations. Especially in IL-6 promoter -174 polymorphism, we found only the G allele associated with higher plasma IL-6 levels. In haplotype analysis of IL-10 promoter polymorphisms, the GCC haplotype, associated with higher expression of IL-10, was significantly lower in Koreans. These results may be helpful for understanding transplant-related complications, immune or autoimmune diseases, and malignant diseases in the Korean population.