Valva P, Gismondi MI, Casciato PC, et al. - Researchers evaluated 27 pediatric and 32 adult liver samples by immunohistochemistry or immunofluorescence for intrahepatic viral infection, apoptosis, and portal and periportal/interface infiltrate in order to better understand the pathogenesis of chronic hepatitis C. Pediatric vs adult samples displayed a higher number of infected hepatocytes. In children, these were noted to be correlated with apoptotic hepatocytes. In addition, the investigators observed a correlation of infected and apoptotic hepatocytes with the severity of fibrosis. In severe hepatitis, increased activated caspase-3⁺ cell count was noted in adults. Adult samples displayed higher total, CD4⁺, CD8⁺, and Foxp3⁺ lymphocyte count. CD8⁺ cells in children demonstrated a correlation with infected and TUNEL⁺ hepatocytes, while in adult samples, these were correlated with activated caspase-3⁺ hepatocytes. In adults, CD8⁺ was noted to be associated with hepatitis severity and with inflammatory activity. Chronic hepatitis C pathogenesis of both pediatric and adult patient thus involves hepatitis C virus, apoptosis, and immune response. However, in pediatric CHC, the liver injury seemed largely associated with a viral cytopathic effect mediated by apoptosis; in adults, it seemed mainly associated with an exacerbated immune response.