title: Expression and function of histamine receptors in human monocyte-derived dendritic cells.
abstract: BACKGROUND
  Histamine is a well-known mediator eliciting different responses in immune and nonimmune cells, but its role in modulating dendritic cell (DC) functions has been marginally investigated.
  
  
  OBJECTIVE
  The purpose of this investigation was to analyze whether human monocyte-derived DCs express functional histamine receptors according to their maturation stage.
  
  
  METHODS
  DCs were derived from monocytes and used as immature or LPS-differentiated cells. DCs were tested for histamine receptor expression, chemotaxis, cytokine release, and the capacity to induce T-cell differentiation in response to specific histamine receptor agonists.
  
  
  RESULTS
  Immature and mature DCs expressed the mRNA for H1, H2, and H3 histamine receptors. Histamine induced intracellular Ca2+ transients, actin polymerization, and chemotaxis in immature DCs. Maturation of DCs resulted in the loss of these responses. In maturing DCs, however, histamine dose-dependently enhanced intracellular cAMP levels and stimulated IL-10 secretion while inhibiting production of IL-12. As a consequence, histamine might contribute to the impairment of generation of allogeneic type 1 responses via maturing DCs. Specific histamine receptor agonists or antagonists revealed that Ca2+ transients, actin polymerization, and chemotaxis of immature DCs were due to stimulation of H1 and H3 subtypes. Modulation of IL-12 and IL-10 secretion by histamine involved the H2 and H3 receptors exclusively.
  
  
  CONCLUSIONS
  Our study suggests that histamine has important biological effects on DC activities, opening the possibility that histamine released during inflammatory or immune responses could regulate DC functions and ultimately favor type 2 lymphocyte-dominated immunity.
authors: Department of Experimental Dermatology, University Hospital, Freiburg, Germany.
authors: Marco
authors: M
authors: Idzko
authors: Andrea
authors: A
authors: la Sala
authors: Davide
authors: D
authors: Ferrari
authors: Elisabeth
authors: E
authors: Panther
authors: Yared
authors: Y
authors: Herouy
authors: Stefan
authors: S
authors: Dichmann
authors: Maja
authors: M
authors: Mockenhaupt
authors: Francesco
authors: F
authors: Di Virgilio
authors: Giampiero
authors: G
authors: Girolomoni
authors: Johannes
authors: J
authors: Norgauer
mesh_terms: D000199:Actins / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000502:physiology; D002630:Chemotactic Factors / Q000494:pharmacology; D003713:Dendritic Cells / Q000166:cytology* / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000276:immunology / Q000517:prevention & control; D016753:Interleukin-10 / Q000378:metabolism; D018664:Interleukin-12 / Q000037:antagonists & inhibitors; D007425:Intracellular Membranes / Q000378:metabolism; D009000:Monocytes / Q000166:cytology*; D011108:Polymers / Q000378:metabolism; D011968:Receptors, Histamine / Q000502:physiology*
chemical_list: D000199:Actins; D002630:Chemotactic Factors; D011108:Polymers; D011968:Receptors, Histamine; D016753:Interleukin-10; D018664:Interleukin-12; D006632:Histamine; D002118:Calcium