title: Histamine induces Th2 activation through the histamine receptor 1 in house dust mite rhinitic but not asthmatic patients.
abstract: BACKGROUND
  Effects of mast cell-released histamine on smooth muscle and endothelial cells are considered as responsible of immediate symptoms of anaphylaxis. However, little is known about histamine effects on Th2 lymphocytes, which orchestrate the allergic reaction upstream of mast cells.
  
  
  OBJECTIVE
  We addressed this question in house dust mite (HDM) allergics, according to the presence of rhinitis or asthma and allergen stimulation.
  
  
  METHODS
  Peripheral blood mononuclear cell from 15 rhinitic and 14 asthmatic HDM-allergic subjects and 16 controls were cultured with Der p 1 or histamine. The effect of Der p 1 on histamine receptor (H1R and H2R) expression was studied. T-cell cytokine production was studied upon Der p 1 or histamine stimulation. The role of H1R in histamine effects was assessed with levocetirizine.
  
  
  RESULTS
  H1R and H2R are overexpressed on T cells from asthmatic but not from rhinitic subjects. Der p 1 increases H1R expression on CD4(+) cells from both allergic groups, and decreases it in controls, on CD4(+) and CD8(+) subsets. Der p 1 decreases T-cell H2R expression in asthmatics. Allergen increases IL-4 and IL-13 in both allergic groups. Histamine increases Th2 cytokines in rhinitics only, and levocetirizine abolishes this effect. In asthmatics and controls, histamine decreases T-cell cytokines through a non-H1R dependent pathway.
  
  
  CONCLUSIONS
  In rhinitis but not in asthma, histamine is able to increase allergic inflammation by increasing Th2 cytokine production in a positive feedback dependent on H1R. This result could explain in part why H1R antagonists, are very efficient in rhinitis, but not in asthma.
authors.affiliation: L'institut du thorax, INSERM U915, Faculté de médecine, Université de Nantes, Nantes, France. botturikarine@yahoo.fr
authors.forename: K
authors.initials: K
authors.lastname: Botturi
authors.forename: Y
authors.initials: Y
authors.lastname: Lacoeuille
authors.forename: D
authors.initials: D
authors.lastname: Vervloet
authors.forename: A
authors.initials: A
authors.lastname: Magnan
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology; D039741:Antigens, Dermatophagoides / Q000276:immunology; D060829:Arthropod Proteins; D001249:Asthma / Q000276:immunology*; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases; D016207:Cytokines / Q000096:biosynthesis; D005260:Female; D006632:Histamine / Q000276:immunology* / Q000494:pharmacology; D006801:Humans; D008213:Lymphocyte Activation; D008297:Male; D011969:Receptors, Histamine H1 / Q000378:metabolism*; D012221:Rhinitis, Allergic, Perennial / Q000209:etiology / Q000276:immunology*; D018418:Th2 Cells / Q000187:drug effects / Q000276:immunology*
chemical_list: D000485:Allergens; D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; D016207:Cytokines; D011969:Receptors, Histamine H1; D006632:Histamine; D003546:Cysteine Endopeptidases; C451162:Dermatophagoides pteronyssinus antigen p 1