Interferon-alpha treatment of six patients with the idiopathic hypereosinophilic syndrome.

OBJECTIVE

To examine the response to interferon-alpha 2B therapy in six patients with the idiopathic hypereosinophilic syndrome.

DESIGN

Prospective cohort study.

SETTING

Tertiary referral center, university hospital inpatient and outpatient clinics, and offices of private practice physicians.

PATIENTS

Six patients satisfying the criteria for the hypereosinophilic syndrome, five of whom were resistant to or intolerant of conventional treatment.

INTERVENTION

Individualized dosages of interferon-alpha based on clinical response and side effects.

MEASUREMENTS

Measurements of eosinophilia (peripheral and bone marrow counts), levels of serum eosinophil major basic protein, doses of glucocorticoid and cytotoxic medications, and transfusion requirements.

RESULTS

Various dosages of interferon-alpha from 1.5 MU/d to 8 MU/d decreased the total eosinophil count to less than 1000/mm3 in five of six patients. All patients were able to taper and discontinue prednisone and hydroxyurea. Both patients with incapacitating mucosal ulcers had resolution and no recurrence of these previously resistant lesions. Interferon-alpha was generally well tolerated except for dose-limiting side effects, including thrombocytopenia in one patient and in a second patient, temporary worsening of mucosal lesions and constitutional symptoms.

CONCLUSIONS

Interferon-alpha is a valuable agent for patients with the hypereosinophilic syndrome who are resistant to or intolerant of conventional therapy and for patients with this syndrome who have incapacitating mucosal ulcers.