title: Lipid mediators from pollen act as chemoattractants and activators of polymorphonuclear granulocytes.
abstract: BACKGROUND
  Under natural exposure conditions, pollen grains function as allergen carriers that release allergens from internal binding sites on contact with the aqueous phase of mucosa membranes. In addition, we recently demonstrated that pollen are a rich source of eicosanoid-like mediators, which are rapidly released on contact with the aqueous phase.
  
  
  OBJECTIVE
  The current study was designed to characterize the biochemical nature of pollen-derived lipid mediators in more detail and to delineate their biologic activity on polymorphonuclear granulocytes (PMNs).
  
  
  METHODS
  Aqueous and lipid extracts from Phleum pratense L and Betula alba L pollen were analyzed by means of HPLC. PMNs were exposed to aqueous extracts or lipid fractions from pollen or to HPLC-purified lipid mediators identified in pollen extracts. Effects on PMNs were tested with transwell migration, calcium mobilization, and surface expression of CD11b.
  
  
  RESULTS
  Aqueous pollen extracts (APEs) contained predominantly monohydroxylated products derived of linoleic acid and linolenic acid. In chemotaxis assays PMNs displayed significant migration to APEs. Lipid extracts from pollen and the HPLC fraction containing 13-hydroxy-octadecadienoic acid/hydroxy-linoleic acid and 13-hydroxy-octadecatrienoic acid/hydroxy-linolenic acid induced migratory responses, although to a lesser degree than the APEs. In addition, APE, as well as lipid, extracts induced PMN activation, as documented by means of calcium mobilization and upregulation of CD11b.
  
  
  CONCLUSIONS
  Pollen grains release mediators that recruit and activate PMNs in vitro. Similar mechanisms may be effective in vivo, suggesting that pollen-derived lipid mediators may act as adjuvants in the elicitation phase of allergic reactions.
authors: Division of Environmental Dermatology and Allergy TUM/GSF, Neuherberg, Germany.
authors: Claudia
authors: C
authors: Traidl-Hoffmann
authors: Anna
authors: A
authors: Kasche
authors: Thilo
authors: T
authors: Jakob
authors: Michael
authors: M
authors: Huger
authors: Sabine
authors: S
authors: Plötz
authors: Ivo
authors: I
authors: Feussner
authors: Johannes
authors: J
authors: Ring
authors: Heidrun
authors: H
authors: Behrendt
mesh_terms: D002465:Cell Movement / Q000187:drug effects; D002630:Chemotactic Factors / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D006801:Humans; D008041:Linoleic Acids / Q000032:analysis / Q000494:pharmacology; D008055:Lipids / Q000032:analysis / Q000494:pharmacology*; D016177:Macrophage-1 Antigen / Q000378:metabolism; D018375:Neutrophil Activation; D009504:Neutrophils / Q000187:drug effects* / Q000502:physiology*; D010936:Plant Extracts / Q000494:pharmacology; D011058:Pollen / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: D002630:Chemotactic Factors; D005231:Fatty Acids, Unsaturated; D008041:Linoleic Acids; D008055:Lipids; D016177:Macrophage-1 Antigen; D010936:Plant Extracts; C027369:octadecadienoic acid