title: Epigallocatechin gallate-induced histamine release in patients with green tea-induced asthma.
abstract: OBJECTIVE
  Epigallocatechin gallate is the causative agent of green tea-induced asthma. To determine whether an IgE-mediated mechanism plays a pathogenetic role in this disorder, we measured histamine release after in vitro exposure to epigallocatechin gallate.
  
  
  METHODS
  Subjects included eight patients (four men and four women) with green tea-induced asthma, who had been diagnosed by skin test and inhalation challenge, and eight controls (four asthmatic subjects with no previous exposure tea dust and four healthy volunteers). Heparinized whole blood samples were taken and incubated with epigallocatechin gallate at various concentrations (final concentration range, 0.003 to 300 micrograms/mL) for 30 minutes at 37 degrees C. After centrifugation, histamine was measured in the cell-free supernatants by radioimmunoassay. Histamine release was expressed as a percentage of total histamine. A result higher than 10% was considered positive.
  
  
  RESULTS
  In one of the tea-sensitive patients, epigallocatechin gallate did not cause histamine release. Five of the other seven patients (71%) demonstrated a positive, dose-dependent histamine release to epigallocatechin gallate. In asthmatic and normal controls, histamine release was not observed at any epigallocatechin gallate concentration. Furthermore, a significant correlation was noted between the maximum percentage histamine release and the threshold epigallocatechin gallate concentration for intradermal skin testing.
  
  
  CONCLUSIONS
  These results indicate that an IgE-mediated response is the basis for green tea-induced asthma.
authors.affiliation: Second Department of Internal Medicine, Hamamatsu University School of Medicine, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Shirai
authors.forename: A
authors.initials: A
authors.lastname: Sato
authors.forename: K
authors.initials: K
authors.lastname: Chida
authors.forename: H
authors.initials: H
authors.lastname: Hayakawa
authors.forename: J
authors.initials: J
authors.lastname: Akiyama
authors.forename: M
authors.initials: M
authors.lastname: Iwata
authors.forename: M
authors.initials: M
authors.lastname: Taniguchi
authors.forename: K
authors.initials: K
authors.lastname: Reshad
authors.forename: Y
authors.initials: Y
authors.lastname: Hara
mesh_terms: D000328:Adult; D016587:Antimutagenic Agents / Q000494:pharmacology*; D001249:Asthma / Q000097:blood / Q000209:etiology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D006636:Histamine Release / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012882:Skin Tests; D013662:Tea / Q000009:adverse effects*
chemical_list: D016587:Antimutagenic Agents; D013662:Tea; D002392:Catechin; C045651:epigallocatechin gallate