T-cell immune activation in children with vertically transmitted hepatitisC virus infection

Little is known concerning the clinical features, the histological outcome, and the effects on the maturation of immune system of children with vertic ally-transmitted hepatitis C virus (HCV) infection. Specifically, no data a re available on the peripheral distribution of T-cell subsets. The frequenc y of naive and memory cells, activated T cells, and cytokine-producing T ce lls was analyzed in nine HCV-infected children born to HCV-positive mothers . In HCV-infected children, the distribution of naive and memory cells was not significantly altered in the CD4 subset whereas within the CDS subset, an increase of memory and a decrease of naive cells was observed. The frequ ency of HLA-DR-positive and Fas-positive T cells was increased in HCV-infec ted children in both CD4 and CD8 subsets. The distribution of Fas-expressin g T cells was directly related to that of HLA-DR cells and inversely relate d to the frequency of naive T cells. In regard with cytokine production we found increased levels of both CD4 and CD8 interferon-gamma (IFN-gamma)-pro ducing cells whereas no difference in the percentage of interleukin-2 (IL-2 )-producing T cells was observed. No meaningful correlation was observed be tween individual T cell subsets and ALT levels or HCV viral load. In conclu sion, our results indicate an increased T-cell activation and a shift to a T(H)1 pattern of cytokine production in children with vertically transmitte d HCV infection. The cause of this kind of immune response could reside in the persistent antigenic stimulation by chronic HCV infection.