Increased number of non-invariant NKT cells and low number of circulating CD1-expressing leukocytes in patients infected with hepatitis C virus.

Natural killer T (NKT) cells represent an heterogeneous T cell population involved in host immunity against several microorganisms. They also have important immunoregulatory functions. Studies on circulating levels of NKT cells during HCV infection have been focused on the invariant NKT (iNKT) subset which recognizes the non-classical Ag-presenting molecule CD1d, with little information about the non-invariant NKT (non-iNKT) cell subset. In the present study, we assessed the number of both NKT cells subsets and the surface expression of CD1a, b, c and d isoforms in peripheral blood of 31 HCV-infected patients and 31 ages matched healthy individuals. A significant increase of circulating non-iNKT cells was observed in HCV-infected patients as compared to controls (74 ± 57 cells/µL vs 42 ± 16 cells/µL respectively, p<0.0042) with no differences in the iNKT subset. In addition, the percentage of CD1a, CD1c and CD1d-expressing leukocytes was significantly low in patients as compared to controls. These findings suggest that both components, non-iNKT cells and CD1 molecules expression are involved in the control of natural immunity against HCV.