A rat model of hypereosinophilic syndrome

Hypereosinophilia-occurring rats without chemical and antigen treatment hav e been maintained in our laboratory. The rat, Matsumoto Eosinophilia Shinsh u (mes), showed hypereosinophilia at the age of 9 weeks or older and develo ped eosinophil-related inflammatory lesions in many organs. These lesions i ncluded: aortitis, granulomatous lesion in the mesenteric lymph node, infla mmatory fibroid polyp of the stomach and pulmonary vasculitis with septal i nfiltration. These lesions were involved with cellular infiltration of eosi nophils and macrophages, and deposition of eosinophilic crystals which immu nohistologically showed major basic protein and eosinophilic peroxidase der ived from eosinophilic lysosomal constituents. Although the distribution of lesions in mes is a little different from that of hypereosinophilic syndro me (HES) in humans, in that endomyocardial fibrosis appears in HES while ao rtitis appears in mes, mes is probably comparable with HES. The present pap er describes the pathological aspects of the lesions in mes and discusses t he pathogenesis of tissue injury related to eosinophilic infiltration.