title: Association of CD40 -1C/T polymorphism in the 5'-untranslated region with chronic HBV infection.
abstract: BACKGROUND
  CD40 is an important costimulatory molecule in both cellular and humoral immune responses, involved in the pathogenic processes of chronic inflammatory diseases. Few studies were performed on the association of CD40 single nucleotide polymorphism (SNP) with chronic hepatitis B virus (HBV) infection. In this study, we studied whether the CD40-1C/T polymorphism had any effect on the progression of chronic HBV infection in Chinese population.
  
  
  METHODS
  CD40 -1C/T polymorphism in the 5'-untranslated region was analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 453 chronic HBV carriers, who were divided into asymptomatic HBV carriers (ASC), moderate chronic hepatitis B group (MCHB) and severe chronic hepatitis B group (SCHB). 202 healthy individuals in the same region were enrolled in this study as the controls. The CD40 expression on B lymphocytes was detected by flow cytometry. The concentrations of soluble CD40 (sCD40) in sera were assayed by a commercial ELISA kit.
  
  
  RESULTS
  Our results showed the frequencies of TT genotype and T allele of CD40-1C/T polymorphism were higher significantly in ASC than those in controls (P< 0.05), while this result was not found in either MCHB or SCHB. On the surface of B lymphocytes, the CD40 expression levels in the individuals with TT genotype were significantly lower than those with CC and CT genotypes in either ASC group or healthy controls (P<0.001). The sCD40 levels in the sera of ASC, MCHB and SCHB groups were significantly higher than the controls (P<0.001).
  
  
  CONCLUSIONS
  The CD40 -1C/T polymorphism may contribute to the susceptibility of asymptomatic HBV carriers through its effect on cell-surface CD40 expression, which indicated CD40 signaling was involved in immune tolerance of chronic HBV infection.
authors.affiliation: State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhou
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Jin
authors.forename: Jie
authors.initials: J
authors.lastname: Tang
authors.forename: Jiaqian
authors.initials: J
authors.lastname: Fei
authors.forename: Chunxia
authors.initials: C
authors.lastname: Gu
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
mesh_terms: D020121:5' Untranslated Regions; D000328:Adult; D000483:Alleles; D001402:B-Lymphocytes / Q000378:metabolism; D019013:CD40 Antigens / Q000097:blood / Q000235:genetics*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D019694:Hepatitis B, Chronic / Q000235:genetics / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide
chemical_list: D020121:5' Untranslated Regions; D019013:CD40 Antigens