An in vitro model of canine immediate-type hypersensitivity reactions.

Fragmented lung prepared from dogs cutaneously sensitive to ascaris antigen released histamine and a slow-reacting substance of anaphylaxis-like (SRS-A) material upon antigen challenge. Passive sensitization of fragments with serum obtained from ascaris-sensitive donor dogs enhanced the release of both substances; heating (56 degrees C for 4 h) destroyed the ability of the serum to enhance release. In passively sensitized tissues isoproterenol and papaverine inhibited the release of histamine and SRS-A; propranolol antagonized the effect of isoproterenol. Carbachol enhanced the release of both substances from passively sensitized lung wheras disodium cromoglycate and aminoguanidine were without effect. It is concluded that fragmented canine lung is a useful model for study of immediate-type hypersensitivity reactions.