title: Dendritic cell membrane CD83 enhances immune responses by boosting intracellular calcium release in T lymphocytes.
abstract: CD83 is a marker of mDCs directly related to their lymphostimulatory ability. Some data suggest that it has a central role in the immune system regulation, but how this function is performed remains to be determined. This work aimed to analyze the influence of CD83, present in mDCs, in the modulation of calcium signaling in T lymphocytes. Mo were differentiated into iDCs and activated with TNF-α. iDCs were treated, 4 h before activation, with siRNACD83, to reduce CD83 expression. Purified allogeneic T lymphocytes were labeled with the calcium indicator Fluo-4-AM, and calcium mobilization in the presence of mDCs was analyzed. CD83 knockdown mDCs induced lower calcium signal amplitude in T lymphocytes (29.0±10.0) compared with siRNAscr-treated mDCs (45.5±5.3). In another set of experiments, surface mDC CD83 was blocked with a specific mAb, and again, decreased calcium signaling in T lymphocytes was detected by flow cytometry and microscopy (fluorescence and confocal). In the presence of antibody, the percentage of responding T cells was reduced from 58.14% to 34.29%. As expected, anti-CD83 antibodies also reduced the proliferation of T lymphocytes (as assessed by CFSE dilution). Finally, in the absence of extracellular calcium, CD83 antibodies abrogated T cell signaling induced by allogeneic mDCs, suggesting that the presence of CD83 in mDC membranes enhances T lymphocyte proliferation by boosting calcium release from intracellular stores in these cells.
authors.affiliation: Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, Brazil.
authors.forename: Mariana Pereira
authors.initials: MP
authors.lastname: Pinho
authors.affiliation: Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, Brazil.
authors.forename: Isabella Katz
authors.initials: IK
authors.lastname: Migliori
authors.affiliation: Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, Brazil.
authors.forename: Elizabeth Alexandra
authors.initials: EA
authors.lastname: Flatow
authors.affiliation: Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, Brazil jbarbuto@icb.usp.br.
authors.forename: José Alexandre M
authors.initials: JA
authors.lastname: Barbuto
mesh_terms: D000906:Antibodies / Q000494:pharmacology; D015703:Antigens, CD / Q000276:immunology*; D020013:Calcium Signaling / Q000187:drug effects / Q000276:immunology*; D002462:Cell Membrane / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology*; D055785:Gene Knockdown Techniques; D006801:Humans; D007111:Immunity, Cellular; D007136:Immunoglobulins / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D000097802:CD83 Antigen
chemical_list: D000906:Antibodies; D015703:Antigens, CD; D007136:Immunoglobulins; D008562:Membrane Glycoproteins; D000097802:CD83 Antigen
keywords: activation; signal transduction; signaling