Impact of IL-22 gene polymorphism on human immunodeficiency virus infection in Han Chinese patients. 
To analyze the polymorphism of the IL-22 gene in Han Chinese patients and to evaluate the influence of IL-22 polymorphism on human immunodeficiency virus (HIV) infection.  IL-22 gene polymorphism was analyzed in 73 blood samples from healthy participants.  The influence of the genotype and allele distribution of three single nucleotide polymorphisms (rs2227484, rs2227485, and rs2227513) of IL-22 on HIV infection was evaluated in 619 HIV seropositive patients and 619 healthy controls.  To determine the association between the rs2227513 genotype and IL-22 levels in plasma, we randomly selected 29 HIV seropositive blood samples and 15 healthy blood samples and measured the levels of IL-22.  Nine single nucleotide polymorphism loci of the IL-22 gene were found (rs2227484, rs2227485, rs2227491, rs2227508, rs2227513, rs1179249, rs1179250, rs1179251, and rs1182844).  Stratified analysis (by sex) showed a higher association of HIV infection and the A/G genotype and G allele at rs2227513 in women, but not in men (A/G genotype odds ratio = 5.24, 95% confidence interval = 1.13-24.27; allele G odds ratio = 5.27, 95% confidence interval 1.15-24.23).  The rs2227513 A/G genotype was also associated with significantly higher levels of plasma IL-22, regardless of whether the patient was HIV seropositive or seronegative.  Our results suggest that IL-22 production in blood might act as a pathogenic factor in HIV infection.