Role of soluble inflammatory mediators and different immune cell populations in early control of symptomatic acute hepatitis C virus infection

The natural course of acute Hepatitis C Virus (aHCV) infection is highly heterogeneous, and only few biomarkers have been identified to reliably predict the outcome of infection. We analysed a large panel of soluble inflammatory mediators, immune cell frequencies and phenotypes using peripheral blood samples from 26 patients with symptomatic aHCV infection from a controlled randomized clinical trial (ISRCTN88729946, www.isrctn.com). We found that patients with a spontaneous early HCV control demonstrated a distinct expression pattern of various soluble immune mediators including IFNα and IL-16. Immune cell phenotype and frequency differed between patients who cleared the viral infection early (n=13) and those who remained HCV RNA positive after 12 weeks of observation (n=13) with a reduced ratio of CD4+ T cells to NK cells in the non-early clearer. Further, correlation analyses of 50 cytokines and chemokines revealed more positive correlations in between the distinct cytokines, especially for IFNα and IL-16, and between the cytokines and HCV RNA levels in spontaneous early clearer patients. Beyond that, in vitro stimulation of CD4+ T cells with IL-16 reduced the susceptibility of these cells to killing by IFNα-activated NK cells. These data indicate that the immune cell composition and cytokine pattern varies considerably in patients with symptomatic aHCV infection. NK cell-mediated killing of CD4+ T cells might affect early control of HCV infection.