BENIGN IDIOPATHIC HYPEREOSINOPHILIA - A FEEBLE MASQUERADER OR A SMOLDERING FORM OF THE HYPEREOSINOPHILIC SYNDROME

In a patient with long-standing idiopathic hypereosinophilia with no a pparent organ damage we measured serum eosinophil cationic protein (EC P) and eosinophil protein X (EPX) titers, activated circulating eosino phil rates (by means of monoclonal antibodies EG1 and EG2), and the re lease of ECP and EPX in vitro by leukocytes at different cultures stag es in order to detect possible functional abnormalities associated wit h hypereosinophilia. Our patient had elevated serum levels of both ECP and EPX, together with a high EG2 count, which would suggest eosinoph il activation. However, serum levels of ECP and EPX were not significa ntly high in relation to the total number of eosinophil cells, althoug h they were more numerous than in healthy controls. Moreover, the rele ase of intracytoplasmic basic proteins by the patient's eosinophils wa s poor even after in vitro stimulation. Since hypereosinophilic syndro me (HES) with organ damage can appear as long as 8-9 years after the p resence of a hypereosinophilic state, the absolutely benign nature of our patient's condition still cannot be defined. Thus, there is the po ssibility it could be slow-onset or smoldering HES.