The production of an unusual tissue reaction in rabbit bowel injected with Crohn's disease homogenates.

Recent reports have suggested a transmissible factor in the etiology of Crohn's disease, which had yet to be confirmed. The specificity of the transmission was tested with a disease control of ulcerative colitis as well as normal bowel. Twenty New Zealand White rabbits received inoculum of tissue homogenates from the terminal ileum of normal, ulcerative colitic, and Crohn's disease patients. This inoculum was injected into the wall of the ascending colon and the animals were examined after one year. Changes were noted consistently only in those animals receiving the Crohn's disease inoculum. These changes consisted of thickened bowel wall with increased mucosal folds, thickened mesenteric fat with some creeping, irregular areas of thin colonic mucosa, and hyperplastic mesenteric lymph nodes. The terminal ileum distant from the inoculum site was smooth with atrophic changes only in the Crohn's inoculated group of animals. These animals also had discrete collections of macrophages in colon or sacculus, mucosal and submucosal edema, and chronic inflammation of the colon. However, the characteristic features of Crohn's disease were not reproduced.