title: Interleukin-10 increases mannose receptor expression and endocytic activity in monocyte-derived dendritic cells.
abstract: Human monocyte-derived dendritic cells were differentiated in vitro for 7 days with granulocyte macrophage-colony stimulating factor and interleukin-13. These cultured dendritic cells are at an immature stage of differentiation and exhert high endocytic activity via surface mannose receptor and via fluid-phase macropinocytosis. We have investigated the modulation of endocytosis by interleukin-10 in these cells. When added during the last 24 h of the 7-day culture, interleukin-10 significantly stimulated the uptake of fluorescein-labelled dextran (39 +/- 16% increase, mean +/- SD of 6 experiments), a sugar binding to the mannose receptor. This effect was dose dependent and correlated with the length of exposure to interleukin-10, with a maximal effect (more than seven-fold increase) when the cytokine was added at the beginning of the culture (day 0). The interleukin-10-increased fluorescein-labelled-dextran endocytosis was mostly mediated via the mannose receptor, as unlabelled mannose and specific antimannose receptor monoclonal antibody inhibited most of the uptake. Moreover, interleukin-10-treated cells expressed increased levels (up to four-fold) of mannose receptor. Interleukin-10 also increased, although to a lesser extent, the fluid-phase endocytosis (macropinocytosis) of fluorescein-labelled albumin. Interleukin-10 had the opposite effect on the differentiation and functional activity of monocyte-derived dendritic cells; cells having a very low stimulatory capacity and reduced expression of MHC class II and CD1a after a 7-day exposure. Thus interleukin-10 had a strong immunosuppressive effect on the differentiation and functional activity of monocyte-derived dendritic cells and yet strongly stimulated endocytosis in these cells. We speculate that an increased endocytic activity would eventually result in a decreased availability of antigens in the external milieu, thus contributing to the immunosuppressive and tolerogenic activity of interleukin-10.
authors.affiliation: Department of Immunology and Cell Biology, Mario Negri Institute, Milan, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Longoni
authors.forename: L
authors.initials: L
authors.lastname: Piemonti
authors.forename: S
authors.initials: S
authors.lastname: Bernasconi
authors.forename: A
authors.initials: A
authors.lastname: Mantovani
authors.forename: P
authors.initials: P
authors.lastname: Allavena
mesh_terms: D000911:Antibodies, Monoclonal; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000737:chemistry* / Q000166:cytology / Q000187:drug effects; D004705:Endocytosis / Q000187:drug effects*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D016130:Immunophenotyping; D016753:Interleukin-10 / Q000494:pharmacology*; D018793:Interleukin-13 / Q000494:pharmacology; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D009000:Monocytes / Q000166:cytology*; D011956:Receptors, Cell Surface / Q000032:analysis / Q000276:immunology / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D018793:Interleukin-13; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D011956:Receptors, Cell Surface; D016753:Interleukin-10; D016178:Granulocyte-Macrophage Colony-Stimulating Factor