title: Dendritic cells generated with Flt3L and exposed to apoptotic cells lack induction of T cell anergy and Foxp3⁺ regulatory T cell conversion in vitro.
abstract: Removal of apoptotic cells, which appear during the steady state, is a pre-requisite to prevent generation of secondary necrotic cells that may lead to autoimmunity. The recognition of apoptotic material by dendritic cells (DCs) has been proposed to convert them into tolerogenic DCs equipped with specialized tolerogenic mechanisms on T cells. However, comparative studies to demonstrate functional alterations of DCs upon exposure to apoptotic cells have not been performed so far. Here we show that immature murine bone marrow-derived DCs generated with GM-CSF (GM-DCs) or Flt3L (FL-DCs) interact with live or apoptotic syngeneic thymocytes. As expected, GM-DCs phagocytose apoptotic but not live cells, FL-DCs only show trogocytosis of membrane parts. Interaction with live or apoptotic thymocytes did not lead to DC maturation. Both GM-DCs and FL-DCs present OVA as protein, peptide and membrane-associated antigens. Interestingly, only GM-DCs were able to induce T cell anergy or convert naïve T cells into FoxP3⁺ regulatory T cells (Tregs) but FL-DCs did not show either of these effects. Unexpectedly, exposure of immature GM-DCs to live or apoptotic thymocytes did not improve DC functions in both types of in vitro T cell tolerance induction assays. Together, our data suggest that these tolerogenic in vitro measures of immature BM-DCs are not further enhanced by exposure to apoptotic cells and may depend on the generating cytokine.
authors.affiliation: Institute of Virology and Immunobiology, University of Wuerzburg, Germany.
authors.forename: Katrien
authors.initials: K
authors.lastname: Pletinckx
authors.affiliation: Institute of Virology and Immunobiology, University of Wuerzburg, Germany. Electronic address: m.lutz@vim.uni-wuerzburg.de.
authors.forename: Manfred B
authors.initials: MB
authors.lastname: Lutz
mesh_terms: D000818:Animals; D017209:Apoptosis; D001854:Bone Marrow Cells / Q000276:immunology*; D002454:Cell Differentiation; D002478:Cells, Cultured; D017635:Clonal Anergy / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology*; D051858:Forkhead Transcription Factors / Q000378:metabolism; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000276:immunology; D007156:Immunologic Memory; D008213:Lymphocyte Activation; D008565:Membrane Proteins / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010587:Phagocytosis; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D060168:Thymocytes / Q000276:immunology / Q000473:pathology
chemical_list: D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D008565:Membrane Proteins; C084881:flt3 ligand protein; D016178:Granulocyte-Macrophage Colony-Stimulating Factor
keywords: Anergy; Apoptotic cells; Dendritic cells; FITC; FL-DCs; Flt3-L; Flt3-L-dependent conventional DCs; GM-CSF-dependent DCs; GM-DCs; MFI; PE; Regulatory T cells; fluorescein isothiocyanate; fms-like tyrosine kinase 3 ligand; mean fluorescence intensity; phycoerythrin