Ultrastructure of the Ileum in Crohn's Disease

Abstract

Electron microscopic investigations of the inflammatory reactions in the intestinal wall and the regional lymph nodes obtained during surgery on patients with Crohn's disease of the terminal ileum showed a marked preponderance of lesions attributable to cell-mediated immune mechanisms. The dominating cells were small and large lymphocytes, many being of the activated, polyribosome-rich type. Plasmacytosis was also present, although to a lesser extent. Epithelioid cell granulomas were found both in the intestinal wall and in the hyperplastic regional lymph nodes. The granulomas were indistinguishable from those seen in sarcoid tissue lesions. Microorganisms could not be found. An unexpected finding was a conspicuously large number of mast cells throughout the tissues involved. Mastocytosis has not hitherto been described as a feature of Crohn's disease and the role of the mast cells in that disorder is unknown.