Ordered array of dendritic cells and CD8+lymphocytes in portal infiltratesin chronic hepatitis C

Aims: Despite the importance of dendritic cells in stimulating primary and secondary immune responses by presenting antigens to T-lymphocytes in drain ing lymph nodes and peripheral tissues, respectively, very limited informat ion is available on the presence and localization of these cells in hepatit is C virus (HCV)-related chronic active hepatitis. Therefore, we addressed the ultrastructure, immunophenotype, distribution and relationships to lymp hatics of dendritic cells in portal infiltrates of this disease. Methods and results: Part of percutaneous diagnostic liver biopsies (Knodel l's histological assessment index: 9-13) was processed for electron microsc opy and for immunohistochemical detection of immune system cell membrane an tigens and of the lymphatic endothelium marker podoplanin. in portal infilt rates. cells with electron microscopical and cell marker features of dendri tic cells and expressing the activation markers CD54, CD80, CD83 and CD86 w ere organized in a discontinuous network, that embedded CD8+ lymphocytes in close contact with dendritic cells and came in contact with hepatocytes. s ometimes infiltrating beyond the limiting plate. Also, dendritic cells were found within newly formed lymphatic capillaries in thin, infiltrated septa among hepatocytes. Conclusions: This evidence strongly suggests a critical role of dendritic c ells and newly formed lymphatics in the pathogenesis and organization of th e immune infiltrate that characterizes HCV-related chronic active hepatitis .