Hypereosinophilic syndromes (HES) and systemic mastocytosis (SMCD) are heterogeneous disorders with clinical symptoms from local and remote effects of excessive proliferation of eosinophils and mast cells, respec tively. Interferon α (IFN-α), alone or in combination with other medications, can be a useful, and at times life-saving, treatment for patients with HES. Receptors for IFN-α are present on eosinophils, and clinical benefits are due to its effect on eosinophil proliferation, migration, activation, and survival. These effects are likely mediated through multiple pathways including, but not limited to, inhibition of eosinophil colony-forming cells, upregulation of IFN-γ synthesis, and inhibition of production of eosinophil-active cytokines by T cells, mast cells, and mononuclear cells. IFN-α has been life-saving for patients with intractable HES that were resistant to prednisone, hydroxyurea, and other agents. Resistance to the eosinopenic effect of IFN-α does not develop and the dose of IFN-α necessary to maintain control of eosinophilia often decreases with time. The combination of IFN-α and hydroxyurea is very useful and allows dosage reduction of IFN-α and better control of hypereosinophilia than with either agent alone. The efficacy of IFN-α for treatment of SMCD has been more difficult to establish, with both favorable and unfavorable results reported. The disparate results may have resulted from the small number of patients with SMCD treated with IFN-α, the use of various criteria for a ‘successful’ treatment outcome, short duration of treatment and follow-up, and the use of modest dosages. In reported series, side effects from IFN-α have frequently been dose-limiting. IFN-α improves many of the clinical symptoms of SMCD including dermatological, hematological, gastrointestinal, and systemic symptoms associated with histamine release. IFN-α has a beneficial effect on skeletal symptoms because of its ability to increase bone density and reduce painful episodes from vertebral fractures. No consistent improvement in bone marrow infiltration by mast cells has been demonstrated except in a recent study employing high dosages of IFN-α. A beneficial effect from the combination of IFN-α and prednisone has been reported for several patients, suggesting that combined use of these two medications may provide synergism in treatment outcomes.

Keywords:
Interferon α2A, Interferon α2B, Interferon =γ, Hypereosinophilic syndrome, Systemic mastocytosis, Tryptase, Interleukin-5, Granulocyte macrophage colony-stimulating factor, Interleukin-13, T cells
© 2005 S. Karger AG, Basel
2005
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.