INVITRO 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.degree. 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 whereas disodium cromoglycate and aminoguanidine were without effect. Fragmented canine lung is a useful model for study of immediate-type hypersensitivity reactions.