ABSTRACT
Background: the mechanism behind the apparent lack of effective antiviral immune response in patients with chronic hepatitis C virus [HCV] infection is poorly understood. Although multiple levels of abnormalities have been identified in innate and adaptive immunity, it is postulated that production of specific cytokines such as IL-10 may contribute to the induction and maintenance of HCV persistence. Production of IL-10 by CD4[+], CD25[+], and IL-10 [+] regulatory T cells with regulatory capacity [Tregs] appears to be one of the viral mechanisms that alter the antiviral immune response. As the first report, that attempts to mimic physiological forces that can occur during HCV infection, in this study we evaluate the ability of HCV-core antigens in increasing the frequency of CD4[+],CD25[+],IL-10[+] regulatory T cells
Materials and Methods: we analyzed peripheral blood mononuclear cells [PBMCs] from chronic HCV-infected patients [n=19] and normal controls [n=6] to determine the effect of the HCV-core antigen in the frequency of HCV-specific IL-10 production. PBMCs of different groups were isolated, cultured and stimulated with core antigen. Then, an in-house triple-stain flow cytometric method was used to investigate the frequency of CD4[+],CD25[+],IL-10 producing cells
Results: following incubation of PBMCs with HCV-core antigen, a population of CD4[+],CD25[+],IL-10[+] cells [regulatory T cells] increased. However we observed no increase in Tregs in the negative controls
Conclusion: the study supports the view that specific CD4[+],CD25[+],IL-10[+] T cells may be implicated in host immune tolerance during an HCV infection. It is likely that HCV vaccine candidates avoid epitopes that lead to strong IL-10 production
ABSTRACT
Regulatory T cells [Tregs] have been involved in impaired immunity and may have a pivotal role in persistence of viral infections. To develop a simple and reliable in-house three color flow cytometery of peripheral blood to understand the role of HCV infection in the increase of Tregs. The level of naturally occurring CD4+ CD25+ FoxP3+ regulatory T cells [nTregs] in 20 chronically infected with hepatitis C virus [HCV] patients was compared to those of 15 healthy individuals by flowcytometry. In a different approach we performed permeabilization and intracellular staining before surface staining which allows the preservation of the surface molecules in the combined detection process and results in the normal frequency of nTregs in blood. Using the optimized method, it was shown that a significantly higher proportion of nTregs in the total CD4+ T cell population was seen in the peripheral blood of chronic HCV patients [0.83 +/- 0.21%, p=0.05] as compared to controls [0.26 +/- 0.1, p=0.05]. Conclusions: In accordance with other studies, we showed that HCV infection induces a dramatic increase in Tregs, which might contribute to the immune response failure during HCV infection