Evaluation of CCR5 expression on NK cells in Iranian patients with occult hepatitis B infection

Abstract

Background: Chemotactic cytokine (CC) motif receptor type 5 (CCR5) also known as "cluster of differentiation 195" (CD195), is found on the surface of natural killer (NK) cells which play a critical role in host antiviral defense. NK cells are involved in immunity against overt and occult hepatitis B virus (HBV) infection. Occult HBV infection (OBI) is characterized by the presence of HBV-DNA despite the absence of hepatitis B surface antigen (HBsAg) in the serum of infected patients. The CCR5 receptor and its ligands play an important role in the immune defense mechanism against HBV. Material and methods: We tested 3700 plasma samples for the presence of HBsAg, hepatitis B core antibody (anti-HBc), and HBV-DNA to identify patients who were HBsAg negative, anti-HBc positive, and HBV-DNA positive (HBsAg-/anti-HBc+/HBV-DNA+) and considered as OBI. Subsequently CD195/CCR5 was used a marker in flow cytometry to isolate NK cells from OBI patients. Results: From the original pool of 3700 patients 352 (9.5%) plasma samples were HBsAg-/anti-HBc+. Among these samples, 57 were HBV-DNA+, representing a total of 57 OBI patients. Flow cytometric analysis indicated that the number and intensity of CCR5/CD195+ NK cells was decreased in cell samples from all of our OBI patients. Conclusion: NK cells in OBI patients may be unable to express sufficient CCR5 to mount an effective immune response to HBV infection.