SUSTAINED REMISSION OF IDIOPATHIC HYPEREOSINOPHILIC SYNDROME FOLLOWING ALPHA-INTERFERON THERAPY

Two patients with idiopathic hypereosinophilic syndrome (HES) refracto ry to treatment with corticosteroids and hydroxyurea received alpha-in terferon (alpha-IFN) for 3 and 1 years, respectively. Eosinophil count s dropped below 1.5 x 10(9)/1 at weekly doses of 2-7 x 3 million units alpha-IFN. More than a year after discontinuation of alpha-IFN, 1 pat ient remains in a stable remission. Granulocyte-macrophage colony-stim ulating factor (GM-CSF)'plasma levels were found to be normal in this patient, although GM-CSF is known to stimulate eosinophil proliferatio n in vitro. Based on the favorable clinical results of alpha-IFN, furt her studies are necessary to define its role in the treatment of HES.