ACTIVATED EOSINOPHILS AND INTERLEUKIN-5 EXPRESSION IN EARLY RECURRENCE OF CROHNS-DISEASE

Endoscopic recurrences after radical surgery for Crohn's disease are u seful for studying the pathogenesis of initial lesions of Crohn's dise ase. Factors predisposing to recurrence are poorly understood, but it has been shown that eosinophilic infiltration of the neoileum may occu r within a few weeks of resection. The aim of this study was to compar e, in nine patients having an ileocolectomy, the infiltration of eosin ophils and their activation state in normal and diseased areas of the neoileum, three months after surgery. Tissue eosinophils were studied by histochemical methods and electron microscopy. Mucosal expression o f interleukin 5 (IL 5), an important eosinophil activating factor was studied using in situ hybridisation. Sixty per cent of patients had en doscopic recurrence at three months. Eosinophil infiltration was more pronounced in diseased than in endoscopically normal areas and was ass ociated with a high expression of IL 5 mRNA. Ultrastructural analysis showed features of eosinophil activation, but no cytotoxic lesions of surrounding inflammatory or epithelial cells. This study suggests that local synthesis of IL 5 associated with eosinophil activation in the tissues could participate in early mucosal damage in Crohn's disease.