Secretion and tissue content of eosinophil cationic protein in Crohn's disease

To define further the role of eosinophils in the pathogenesis of Crohn's disease, the secretion rate and tissue content of eosinophilic cationic protein (ECP) were measured in colorectal samples. Mucosal biopsies were obtained from 22 controls and 20 patients with Crohn's disease during colonoscopy. After measurement of the initial basal ECP, release samples were incubated using a mucosa oxygenation system. Spontaneous and antiimmunoglobulin E (anti-IgE)-induced secretions of ECP were measured at different time points. For detection of the remaining tissue, ECP amount samples were mechanically homogenized after the incubation period. ECP measurement was performed by radioimmunoassay. Spontaneous ECP secretion rates during the incubation period were similar in all patient groups, whereas the initial basal ECP secretion was significantly increased in tissue affected by Crohn's disease. After stimulation with anti-IgE, ECP secretion was increased two-fold in controls and three-fold in patients with Crohn's disease. In tissue affected by Crohn's disease, ECP levels were found to be significantly increased in most segments of the lower gastrointestinal tract with the highest ECP concentrations in affected mucosa. This functional study demonstrates an enhanced immunologically mediated ECP secretion and an accumulation of ECP in the intestinal mucosa of Crohn's disease, indicating a local upregulation of eosinophils.