EXPRESSION OF COSTIMULATORY MOLECULES BY KUPFFER CELLS IN CHRONIC HEPATITIS OF HEPATITIS-C VIRUS ETIOLOGY

In this paper we show that in viral hepatitis most Kupffer cells (KCs) are activated and express high levels of CD80, CD40, and class-II MHC molecules, thus acquiring the phenotype of professional antigen prese nting cells (APCs). Activated KCs display a close contact with CD4+ T lymphocytes and form KCs-T lymphocyte clusters. Clusters are found wit hin the sinusoids, across the sinusoid wall, and within the liver pare nchima as well, as a consequence of transendothelial migration (TEM), The positivity of activated KCs for hepatitis C virus (HCV) antigens, which likely reflects phagocytosis of infected hepatocytes, suggests t hat KCs-T cell clusters represent the morphological expression of the functional interaction between KCs acting as professional APCs and ant igen-experienced CD4+ T lymphocytes within the liver. These phenotypic and morphological changes are distinct features of livers in chronic hepatitis patients compared with controls.