Immunopathology of guinea pig autoimmune enterocolitis induced by alloimmunisation with an intestinal protein.

An enterocolitis has been induced in guinea pigs by alloimmunisation with a mucosal protein. A single dose of immunogen fails to provoke a synthesis of precipitant antibodies, but a high percentage of animals, injected with two or more doses, develop these antibodies. A specific cell mediated immune response was already detectable 30 days after a single dose of immunogen. At later periods and after multiple doses of immunogen positive results were still found, although in a lesser percentage of the animals. The pathology was characterised by the appearance of multiple mucosal ulcerations, congestion, oedema and localised haemorrhage. The target organs were mainly ileum and descending colon. At later periods a combination of mononuclear cell infiltration, fibrocytic proliferation and granuloma formation appeared together with the other lesions. When an intraluminal challenge was made 48 hours before death, a heavy mononuclear cell infiltration was present in the contact area. The lesions appeared to extend to areas which usually remained unaffected. The characteristic immunopathology of this autoimmune enterocolitis in guinea pigs possesses some of the features of human inflammatory bowel diseases and makes it a useful model for further studies.