IL21 and IL21R polymorphisms and their interactive effects on serum IL-21 and IgE levels in patients with chronic hepatitis B virus infection.

Interleukin (IL)-21 may affect both T-cell and B-cell responses and was suggested to be involved in response to HBV infection. This study explored IL21rs907715 and rs2221903 and IL21R T-83C and rs3093301 polymorphisms and serum IL-21 and IgE levels in 395 patients with chronic HBV infection, 75 HBV infection resolvers and 174 healthy controls. IL21R T-83C was not polymorphic in the study populations. IL21 rs2221903 AG was less frequent in HBV patients than in resolvers (p<0.001, OR=0.364, 95% CI=0.211-0.629) or in controls (p=0.017, OR=0.589, 95% CI=0.381-0.911). IL21R rs3093301 TT was more frequent in HBV patients than in controls [p value after Bonferroni correction (pc)=0.022, OR=1.908, 95% CI=1.158-3.142] and more frequent in resolvers than in controls (pc=0.010, OR=2.965, 95% CI 1.375-6.392). The carriage of IL21 rs2221903 AG/IL21R rs3093301 CT+IL21 rs2221903 AG/IL21R rs3093301 TT was less frequent in patients than in resolvers (pc=0.007, OR=0.236, 95% CI=0.096-0.579) and more frequent in resolvers than in controls (pc=0.014, OR=4.354, 95% CI=1.660-11.420). IL21 rs2221903 was, by interaction with IL21R rs3093301, associated with serum IL-21 and IgE levels in HBV patients. It is suggested that IL21 rs2221903 and IL21R rs3093301 polymorphisms may, independently or interactively, affect the susceptibility to and/or persistence of HBV infection potentially through altering IL-21 and IgE production.