title: Histamine and tryptase in nasal lavage fluid following challenge with methacholine and allergen.
abstract: BACKGROUND
  The level of histamine in nasal lavage fluid has been used as an index of mast cell/basophil activation in a number of studies. Obviously, such an index can only be valid if changes in the secretory activity of nasal glands do not affect the level of histamine in lavage fluid (i.e. hypersecretion, without a simultaneous activation of mast cells/basophils in the nasal mucosa, must not increase the level of histamine).
  
  
  OBJECTIVE
  To asses the effect of nasal hypersecretion on histamine levels in lavage fluid.
  
  
  METHODS
  Nasal challenges were performed with methacholine and allergen in grass pollen-allergic patients and non-allergic controls. Nasal lavage fluid was collected before and repeatedly for nine hours after nasal challenge, and the level of histamine was compared with that of a specific mast cell-derived enzyme, tryptase. In addition, the effect of methacholine on basophils was examined in vitro.
  
  
  RESULTS
  Allergen challenge of allergic patients produced sneezing and a significant increase in histamine and tryptase levels, whereas challenge of non-allergic subjects produced no such response. Interestingly, challenge with methacholine also induced a significant increase in histamine levels. This increase was seen in both allergic and non-allergic subjects and it was not associated with any sneezing or increase in tryptase levels, indicating that mast cells were not activated. Furthermore, stimulation of basophils with methacholine did not induce any histamine release in vitro.
  
  
  CONCLUSIONS
  Apparently, there exists a pool of histamine in the human nose that can be transferred to lavage fluid during glandular hypersecretion. The source of this histamine is yet to be identified. As the level of histamine seems to be affected by the secretory activity of nasal glands, we question the use of this single mediator as an index of mast cell/basophil activation in nasal lavage studies.
authors.affiliation: The Allergy Unit, National University Hospital, Copenhagen, Denmark.
authors.forename: H H
authors.initials: HH
authors.lastname: Jacobi
authors.forename: P S
authors.initials: PS
authors.lastname: Skov
authors.forename: G T
authors.initials: GT
authors.lastname: Kampen
authors.forename: L K
authors.initials: LK
authors.lastname: Poulsen
authors.forename: C M
authors.initials: CM
authors.lastname: Reimert
authors.forename: C
authors.initials: C
authors.lastname: Bindslev-Jensen
authors.forename: C
authors.initials: C
authors.lastname: Praetorius
authors.forename: H J
authors.initials: HJ
authors.lastname: Malling
authors.forename: N
authors.initials: N
authors.lastname: Mygind
mesh_terms: D000281:Administration, Intranasal; D000328:Adult; D000485:Allergens / Q000008:administration & dosage / Q000276:immunology*; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology / Q000494:pharmacology; D001491:Basophils / Q000187:drug effects / Q000276:immunology; D016085:Bronchoconstrictor Agents / Q000008:administration & dosage / Q000276:immunology*; D053818:Chymases; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D006632:Histamine / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000008:administration & dosage / Q000276:immunology*; D008875:Middle Aged; D017817:Nasal Lavage Fluid / Q000737:chemistry / Q000276:immunology*; D011058:Pollen / Q000276:immunology; D012697:Serine Endopeptidases / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D012912:Sneezing / Q000187:drug effects / Q000276:immunology; D053802:Tryptases
chemical_list: D000485:Allergens; D000888:Antibodies, Anti-Idiotypic; D016085:Bronchoconstrictor Agents; C026408:anti-IgE antibodies; D016210:Methacholine Chloride; D006632:Histamine; D012697:Serine Endopeptidases; C083294:chymase 2; D053818:Chymases; D053802:Tryptases