Effect of lung tissue on the inhibitory actions of isoprenaline, theophylline, disodium cromoglycate and PGE1 on antigen-induced mast cell degranulation.

Isoprenaline, disodium cromoglycate and PGE1 poorly inhibit antigen-induced degranulation of sensitised rat peritoneal mast cells, but in the presence of chopped rat lung their inhibitory activities were markedly enhanced. The chopped lung preparation had no effect on degranulation in the absence of an inhibitor and did not enhance the weak inhibitory potency of theophylline. Lung tissue suspensions pretreated with isoprenaline released a factor into the supernatant which enhanced the action of isoprenaline on peritoneal mast cells. The activity of this supernatant factor was destroyed by boiling for 5 min. Supernatant fluid from untreated lung tissue did not itself reduced antigen-induced degranulation or enhance the inhibitory potency of isoprenaline.