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Interferon-α Treatment and Formation of Factor VIII Antibodies
- Mike Makris, MA, MD; and
- F. Eric Preston, MD
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TO THE EDITOR:
In their small controlled study, Mauser-Bunschoten and colleagues [1] found the same incidence of antibodies to factor VIII (inhibitors) in hemophiliacs treated with interferon-α as in the untreated control group. The authors concluded that interferon-α does not increase the risk for development of factor VIII inhibitors. The incidence of new inhibitors in the control group, however, is 92 cases per 1000 patient-years; this rate is more than 20 times greater than that previously reported in the Netherlands (4.4 per 1000 patients-years) [2]. Furthermore, at approximately the same time during which their interferon-α trial was being conducted, an unexpected and sudden increase in inhibitors occurred in their center that was related to a new pasteurized factor VIII concentrate [2]. It is clearly important to know whether any of the patients in this study received the implicated factor VIII product.
Since 1987, we have treated 36 hemophiliacs with interferon and have seen only one case of a new factor VIII antibody. This patient is a 44-year-old man with severe hemophilia A. He is negative for human immunodeficiency virus but positive for antibody to hepatitis C virus. A liver biopsy specimen obtained in 1989 revealed chronic persistent hepatitis; as a result, the patient received interferon-α 2b for 6 months. He had a transient response and relapsed soon after interferon therapy was discontinued. In 1992, the patient was treated with a 1-year course of interferon-α 2a and once again had a transient response. Four months after discontinuation of interferon treatment, however, he developed factor VIII inhibitors with a human level of 30 Bethesda units and a porcine level of 4 Bethesda units (he has never been exposed to porcine factor VIII). During the last 3 years, the level of the human inhibitor has decreased to 2.7 Bethesda units; the porcine inhibitor is now undetectable.
The size of Mauser-Bunschoten and colleagues' study and the extremely high incidence of inhibitors in their control group make it highly unlikely that the authors would have detected a significant increase in inhibitor development after interferon-α treatment.
Mike Makris, MA, MD
F. Eric Preston, MD
Royal Hallamshire Hospital; Sheffield, S10 1SG, United Kingdom
The Editors welcome submissions for possible publication in the Letters section. Authors of letters should:
•Include no more than 300 words of text, three authors, and five references
•Type with double-spacing
•Send three copies of the letter, an authors' form signed by all authors, and a cover letter describing any conflicts of interest related to the contents of the letter.
Letters commenting on an Annals article will be considered if they are received within 6 weeks of the time the article was published. Only some of the letters received can be published. Published letters are edited and may be shortened; tables and figures are included only selectively. Authors will be notified that the letter has been received. If the letter is selected for publication, the author will be notified about 3 weeks before the publication date. Unpublished letters cannot be returned.
Annals welcomes electronically submitted letters.
- Copyright ©2004 by the American College of Physicians
