PDCD1 polymorphism amplifies the predisposing effect conferred by CTLA4 polymorphism in chronic hepatitis B virus infection.

Programmed cell death 1 (PDCD-1) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) both negatively regulate the T-cell response in chronic hepatitis B virus (HBV) infection. This study determined genotypes of PDCD1 -606 G/A and +8669 G/A and CTLA4 -318 C/T and +49 A/G polymorphisms in 172 chronic HBV patients and 145 healthy controls and analyzed the interaction between these polymorphisms of the 2 genes. The results indicated that carriage of the PDCD1 +8669 A allele was increased in HBV patients carrying the CTLA4 -318 CC genotype and carrying the CTLA4 +49 AA genotype compared with controls carrying the CTLA4 -318 CC genotype (80.2% vs 64.8%, p = 0.002, odds ratio [OR] = 2.202, 95% confidence interval [95% CI] = 1.326-3.656) and carrying the CTLA4 +49 AA genotype (18.6% vs 9.7%, p = 0.024, OR = 2.139, 95% CI = 1.093-4.187), respectively. More obviously, carriage of the PDCD1 +8669 AA genotype was significantly increased in HBV patients carrying the CTLA4 +49 AA genotype compared with controls carrying the same CTLA4 +49 genotype (14.0% vs 3.4%, p = 0.001, OR = 4.541, 95% CI = 1.686-12.230). These results suggest that the PDCD1 +8669 A allele and AA genotype may amplify the predisposing effect conferred by the CTLA4 polymorphism through PDCD1 and CTLA4 gene interaction in chronic HBV infection.