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

Objective and Design: Currently no method is available for measurement of mediator release from intact human lung. In this study, a microdialysis technique was used to measure histamine release from mast cells in human lung tissue ex vivo.¶Material: Microdialysis fibers of 216 μm were inserted into lung tissue and perfused with Krebs Ringer buffer at a rate of 3 μl/min. After a 15 min period of steady-state perfusion, anti-IgE and vehicle were injected into the lung tissue above individual fibers. Samples from each fibre were collected for 20 min at 2 min intervals. Histamine was assayed fluorometrically.¶Results: Anti-IgE concentrations of 40–40,000 U/ml dose-dependently released 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. Monocyte chemoattractant protein-1, a potent basophil secretagogue, did not induce histamine release in lung tissue which indicated mast cells to be the histamine 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 lung tissue without any dispersion or enzymatic treatment.