The potential role of regulatory t cells and TGF-β1 in downregulating NKG2D killer activator receptor expression on cytotoxic cells in patients with chronic HCV hepatitis

Aims: Impaired natural killer (NK) cell activity has been proposed to contribute to viral persistence in HCV infection. Recent studies demonstrated that in tumors regulatory T cells (Treg) the secreted TGFβ1 down-regulates NKG2D killer activator receptor and NK cytotoxicity. Since in chronic hepatitis C plasma TGFβ1 level is also increased, we analyzed whether decreased NK activity corresponds to a dysregulated expression of NKG2D. Correlation between the percentage of Treg cells, TGFβ1 levels and NKG2D expression was also studied. Methods: The percentage of peripheral CD4+CD25high+Treg cells, NKG2D+ NK and T ce…