ABSTRACT
Occult hepatitis B infection [OBI] is defined as a form of hepatitis B that despite absence of detectable HBsAg, HBV-DNA is present in patient's peripheral blood. Genetic and immunological differences appear to play important roles in producing OBI. Therefore, this project was aimed to examine the expression of a chemokine receptor [CCR5] on CD8[+] T cells of OBI patients. In this experimental study, 3,700 HBsAg- plasma samples were collected. Samples were tested for anti-HBc antibody and all of HBsAg-/anti-HBc[+] samples were screened for HBV-DNA by PCR. HBV-DNA positive samples were assigned as OBI cases. Also, flow cytometry analysis was performed to examine the expression of CCR5 on CD8[+] T cells of OBI patients. Results of current study showed that 352 [9.5%] cases of samples were positive for anti-HBc. Examination of HBsAg/anti-HBc[+] samples for HBV-DNA by PCR showed that 57 [16.1%] cases had HBV-DNA. Flow cytometric studies indicated lymphocytosis in these patients; however, the number of cells which expressed CD8[+] and CCR5 is decreased significantly in patients, compared to healthy control. In addition to CD8[+] T cells, the expression of CCR5 is also decreased on all immune cells. One of the chemokine receptors which are expressed by CD8[+] T cells is CCR5 and these cells are recruited to infected tissues, including liver by CCR5. Therefore, based on results of this investigation, one may conclude that due to the decreased expression of CCR5, the CD8[+] T cells are unable to respond to the chemokines [CCR5 ligands] and, hence, can not immigrate to the infected liver and incorporate in clearance of hepatitis B virus