Ileal Crohn tissue and concomitant flora inoculated into germfree rats.

During the last decade, the presence of a transmissible agent in Crohn's disease has been disputed. Some authors have observed granulomatous changes in laboratory animals inoculated with Crohn tissue, while others have failed to do so. The reason for these differences in results might inter alia be the susceptibility of the recipient animals and/or the handling of the Crohn tissue. In the present study germfree rats, which are known ot be highly susceptible to microbial agents, were inoculated with ileal Crohn tissue with adjacent content. The Crohn tissue was handled in a way securing the least possible influence of oxygen on the anaerobic part of the flora. The animals were exsanguinated after 35 weeks. Specimens from the gastrointestinal tract and related organs were removed and examined histologically. In all 264 specimens from inoculated rats and 144 from untreated controls were examined. None of the inoculated germfree rats showed any patho-anatomical changes or other features related to Crohn's disease.