MEDIATORS OF ANTIGEN-INDUCED GASTRIN-RELEASE - ROLE OF ANTIGEN-ANTIBODY COMPLEXES AND THE COMPLEMENT-SYSTEM

That orally administered antigen was shown to induce gastrin release i n immunized animals was a new aspect of gastrointestinal physiology. T he mediators responsible for this immunological effect are still uncle ar. In an attempt to discover more about the mechanisms regarding anti gen-induced gastrin release, we developed an in vitro system where fra gments of rat antral mucosa were challenged. This makes it possible to determine the role of antigen-antibody complexes and the complement s ystem in the mechanism of antigen-induced gastrin release. Wistar rats were immunized in vivo with NIP-OVA and mucosal fragments were challe nged in vitro with NIP-HGG. Gastrin was determined after a preincubati on and a challenged incubation period without supernatants. After anti genic challenge, supernatants were used for in vitro challenge in orde r to rule out the presence of a soluble mediator and activation of com plement. In a second group of experiments Wistar rats were used to stu dy in vitro the release of specific antibodies after antigenic challen ge. With this experimental design we were able to show increased gastr in secretion after antigenic challenge in vitro in the presence of int act tissue. It is shown that the increased gastrin release is most pro bably mediated by activation of the complement system in the presence of antigen-antibody complexes. These are built up by specific anti-NIP antibodies and NIP-HGG used for the challenge. The complement system might be the final pathway of the observed increased gastrin release.