Abstract

Direct tissue isoelectric focusing was used as a procedure to analyze differences in soluble tissue protein profiles of resected intestinal segments and endoscopic biopsies from patients with ulcerative colitis, Crohn's disease, and colonic cancer. Extraction of tissue proteins was accomplished by electrophoresis of mucosal cryostat sections on agarose gels across a broad pH gradient. The inflamed colonic mucosa from Crohn's disease patients showed similar isoelectric focusing protein patterns. Small bowel mucosa from a patient with both colonic diverticular disease and Crohn's disease showed protein patterns identical with that of the mucosa from a patient with only Crohn's disease. The inflamed mucosae from ulcerative colitis patients revealed identical protein patterns but were distinct from those of non-inflamed ulcerative colitis mucosa and from the inflamed mucosae from Crohn's disease patients. Non-inflamed small bowel mucosae from cancer, ulcerative colitis, and Crohn's disease patients showed distinct protein patterns which were absent in the non-inflamed large bowel mucosae. The inflamed resected ileum of a Crohn's disease patient exhibited protein patterns similar to those of the biopsy of an inflamed mid-transverse large bowel. Mucosal biopsies from inflamed sigmoid colon of a Crohn's disease patient showed different protein patterns than those in biopsies from the inflamed mid-transverse colon. Thus, distinctive isoelectric focusing protein patterns may be useful in differentiating Crohn's colitis and ulcerative colitis when granulomata are absent, and in resolving indeterminant colitis to one of these classic inflammatory bowel diseases.