Background & Aims: Although clinical and pathological differences exist between Crohn's disease (CD) and ulcerative colitis (UC), distinguishing features are often absent, making diagnosis and treatment problematic. This study evaluated the differences in the expression of substance P (SP) receptors in patients with CD or UC. Methods: Tissue samples from patients with inflammatory bowel disease or control patients were obtained at surgery, processed for 125I-SP binding, and analyzed by quantitative autoradiography. Results: Patients with CD showed a massive increase in SP receptors in lymphoid aggregates, small blood vessels, and enteric neurons of the small and large bowel relative to controls. Six of 16 CD specimens had no pathological evidence of CD yet continued to express high concentrations of SP receptors. Pathologically positive patients with UC showed high concentrations of SP receptors on colonic lymphoid aggregates and small blood vessels but not enteric neurons. No increased SP binding was evident in clinically and pathologically quiescent UC colons and normal UC ileostomy samples. Conclusions: The increased expression of SP receptors on the enteric neurons of patients with CD distinguishes CD from UC. The persistent increased SP binding in pathologically normal CD tissue may indicate a subclinical disease state. SP receptor expression may have important diagnostic, etiologic, and therapeutic usefulness in inflammatory bowel disease.
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