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Abstract
T cells constitutively expressing both CD4+ and CD25+ are essential for maintenance of self-tolerance therefore have been referred to as natural regulatory T cells (natural T reg cells) (Wolf et al., 2003). These cells exert a controlling role during infectious processes. Natural T reg cells may limit the magnitude of effector responses via suppressing the function of dendritic cells, T cells and natural killer cells (NK), which may result in failure to adequately control infection (Stoop et al., 2004) (Belkaid and Rouse, 2005).
Natural T reg cells play a pivotal role in HCV infection; a chief complication of which is massive liver damage that after requires organ transplant. Liver biopsies obtained at the time of the transplant show an inverse correlation between the natural T reg cells in the peripheral blood and the histological inflammatory site (Cabrera et al., 2004).
HCV is a disease in which involvement of natural T reg cells impedes the immune defense. Chronically infected patients have more circulating natural T reg cells in peripheral blood than do uninfected people. T reg cell suppression is dependant on TGF-β and cell contact. Notably, patients chronically infected with HCV who develop autoimmunity show considerable reduction in their peripheral natural T reg cells number (Boyer et al., 2004).