EPIGALLOCATECHIN GALLATE-INDUCED HISTAMINE-RELEASE IN PATIENTS WITH GREEN TEA-INDUCED ASTHMA

Background and Objective: Epigallocatechin gallate is the causative ag ent of green tea-induced asthma. To determine whether an TgE-mediated mechanism plays a pathogenetic role in this disorder, we measured hist amine release after in vitro exposure to epigallocatechin gallate. Met hods: Subjects included eight patients (four men and four women) with green tea-induced asthma, who had been diagnosed by skin test and inha lation challenge, and eight controls (four asthmatic subjects with no previous exposure to tea dust and four healthy volunteers). Heparinize d whole blood samples were taken and incubated with epigallocatechin g allate at various concentrations (final concentration range, 0.003 to 300 mu g/mL) for 30 minutes at 37 degrees C. After centrifugation, his tamine 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 th e tea-sensitive patients, epigallocatechin gallate did not cause hista mine release. Five of the other seven patients (71%) demonstrated a po sitive, dose-dependent histamine release to epigallocatechin gallate. Ln asthmatic and normal controls, histamine release was not observed a t any epigallocatechin gallate concentration. Furthermore, a significa nt correlation was noted between the maximum percentage histamine rele ase and the threshold epigallocatechin gallate concentration for intra dermal skin testing. Conclusion: These results indicate that an IgE-me diated response is the basis for green tea-induced asthma.