Ghasem Mosayebi - Molecular and Medicine Research Center, School of Medicine, Arak University of Medical Sciences, Arak, Iran
Sayyed Mohammad Moazzeni - Department of Immunology, School of Medical Sciences, Tarbiat Modarres University, Tehran, Iran

Introduction Dendritic cells (DCs) are bone marrow-derived cells, which migrate to lymphoid and non-lymphoid organs via blood. Liver DCs are believed to play an important role in the regulation of hepatic allograft acceptance. However, because of inherent difficulties in isolating adequate numbers of DCs from liver, limited information is available on the phenotype and functions of liver DCs. To address this issue, we isolated DCs from normal C۵۷BL/۶ mouse liver using a modified procedure and described their immunophenotypic characteristics. Materials and Methods Non-parenchymal cells (NPCs) were obtained by collagenase digestion of perfused liver fragments and density gradient centrifugation (۱۴.۵% nycodenz column). After overnight (۱۸ hr) incubation of the NPCs, enrichment for transiently adherent, low- density cells on ۱۳% nycodenz gradients permitted the recovery of low numbers of cells (approximately ۱.۲-۱.۵ x ۱۰۵ per liver), many of which displayed distinct DCs morphology (abundant cytoplasm with prominent projections and irregularly shaped nuclei). Results Flowcytometric analysis revealed that most of these cells were recognized by anti-CD۱۱c (۶۰-۷۰%). The results obtained from double staining with PE and FITC conjugated monoclonal antibodies indicated that these cells were CD۱۱c+/MHC-II+ (۵۳%), CD۱۱c+/CD۸۶+ (۵۳.۵%), CD۱۱c+/ CD۸a+ (۳۶%) and CD۱۱c+/CD۱۱b+ (۴۵%). Conclusion These findings indicate that the purity of DCs isolated by nycodenz gradient is higher than other reported methods. Considering the similar ratio of lymphoid (CD۱۱c+/CD۸a+) and myeloid (CD۱۱c+/CD۱۱b+) DCs in the liver, and the known role of lymphoid DCs in tolerance induction, it seems that this subpopulation of DCs is not the main reason of liver tolerogenecity. Therefore, other factors such as the immaturity of liver DCs or the effect of liver microenvironment on these cells, etc. may explain the acceptance of hepatic allograft.

Dendritic cells, Liver, Mice, Phenotype