Pharmacologic regulation of antigen-induced mediator release from canine lung.

The ascaris antigen-induced release of histamine and a slow-reacting substance of anaphylaxis (SRS-A) from passively sensitized fragmented canine lung is further characterized. Histamine and SRS-A were released within 30 sec of antigen challenge, reached a maximum at 7 and 10 min, respectively, and thereafter appeared to remain constant to 30 min. Contractions of guinea pig ileum produced by canine SRS-A were competitively antagonized by the SRS-A antagonist FPL-55712. Indomethacin and deuterium oxide enhanced antigen-induced SRS-A release from canine lung but had little effect on histamine release. The ability of several chemically novel 'antiallergic agents' to inhibit mediator release was evaluated. Inhibition of histamine release, and to a lesser extent SRS-A release, by one of these compounds was shown to vary with time and temperature. It is concluded that fragmented canine lung, while disclosing some qualitative pharmacological differences from other species, is a useful in vitro model of immediate hypersensitivity reactions.