Measurement of histamine release from human lung tissue ex vivo by microdialysis technique

Objective and Design: Currently no method is available for measurement of m ediator release from intact human lung. In this study, a microdialysis tech nique was used to measure histamine release from mast cells in human lung t issue ex vivo. Material: Microdialysis fibers of 216 mu m were inserted into lung tissue a nd perfused with Krebs Ringer buffer at a rate of 3 mu l/min. After a 15 mi n period of steady-state perfusion, anti-IgE and vehicle were injected into the lung tissue above individual fibers. Samples from each fibre were coll ected for 20 min at 2 min intervals. Histamine was assayed fluorometrically . Results: Anti-IgE concentrations of 40-40,000 U/ml dose-dependently release d histamine, significant histamine release being demonstrated with anti-IgE concentrations of 400 U/ml and greater. The kinetics of histamine release showed peak values 2-8 min after the injection. Great individual responses were observed but data could be reproduced within individual donors. Monocy te chemoattractant protein-1, a potent basophil secretagogue, did not induc e histamine release in lung tissue which indicated mast cells to be the his tamine source. Substance P did not release histamine in the lung tissue. Conclusions: The microdialysis technique allowed measurements of histamine release from mast cells in intact lung ex vivo. The method may prove useful since a number of experiments can be performed in a few hours in intact lu ng tissue without any dispersion or enzymatic treatment.