Interferon alfa susceptibility factors

In addition to the underlying disease, there are many potential susceptibility factors (499,519). There is as yet no definitive evidence that age, sex, dose, and duration of treatment play an important role in the development of thyroid disorders. However, patients with previous thyroid abnormalities are predisposed to develop more severe thyroid disease (SEDA-20, 328). The incidence of thyroid disease was not different between natural and recombinant interferon alfa. Although this should be taken into account, a previous familial or personal history of thyroid disease was generally not considered a major risk factor. Finally, only pre-treatment positivity or the development of thyroid antibodies during treatment seem to be strongly associated with the occurrence of thyroid dysfunction. 

Interferons were originally discovered as proteins that interfered with virus replication. When mice were injected with antibodies to interferons, they became markedly susceptible to virus-mediated disease, including virus-related tumour induction. Interferons can be detected at low levels in most human tissues, but amounts increase upon infection with viruses, bacteria, protozoa, and exposure to certain growth factors. Interferons were initially classified according to the cellular source, but recent nomenclature is based primarily on sequencing data. Thus leukocyte interferon (a mixture of proteins) is now known as interferon alfa, fibroblast interferon as interferon beta, and immune interferon as interferon gamma. 

In addition, patients with this allele had neuropsychiatric events sooner than patients without it. In another study in 14 patients with chronic hepatitis C, lower baseline serum activities of propylendopeptidase and dipeptyl peptidase IV, which both play a role in the pathophysiology of major depression, were possible predictors of higher depressive and anxiety scores during interferon alfa treatment (378). Whether these factors help to predict susceptibility to interferon alfa-induced neuropsychiatric disorders in clinical practice needs to be further investigated. 

The study identified female sex, a dose of interferon alfa above 15 MU/week, and naive patients as independent susceptibility factors for premature withdrawal. 

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