Assay of Interferons

Several lines of evidence have been obtained that correlate biological activity with reactivity in an immunoradiometric assay (IRMA) employing two different monoclonal antibodies. Antiviral activity and immunological reactivity decreased in parallel when freeze-dried human gamma-interferon (HuIFN-gamma) was heated for prolonged periods of time at elevated temperatures. Likewise, aqueous preparations of HuIFN-gamma inactivated by acid pH or heat responded similarly in the biological assay and IRMA. These results indicate that the monoclonal antibodies used in this commercially available IRMA are specific for the epitopes on biologically activity HuIFN-gamma.

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“…2). Although most IFN immunoassays appear to be rather insensitive to IFN, all have higher reproducibility than biological assays.…”

Section: Discussionmentioning

confidence: 98%

HuIFN-γ Antiviral Activity Correlates with Immunological Reactivity in a Double-Monoclonal Antibody Radiometrie Assay

Sedmak¹,

Siebenlist²,

Grossberg³

1985

Journal of Interferon Research

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“…The presence of NAb in sera is determined in special bioassays that measure the ability of antibodies to reduce IFN beta bioactivity. The biologic assays most frequently employed to determine the levels of NAb to type I IFN are based on antiviral activities such as yield reduction or cytopathic effect or, less frequently, the inhibitory effect of the antibodies on the proliferation of T lymphocytes (34). The antiviral assay (AVA), which measures the residual activity of IFN beta against viral cytopathic effect after the addition of potentially neutralizing sera, is the most commonly-used biologic assay, and was recommended by the World Health Organization (WHO) (35).…”

Section: Assays For Anti-ifn Antibody Titrationmentioning

confidence: 99%

Anti-interferon antibodies in multiple sclerosis. Molecular basis and their impact on clinical efficacy

Durelli

Ricci²

2004

Front Biosci

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Low levels of naturally-occurring, high-affinity antibodies directed against cytokines can be found in the circulation of individuals who have never been exposed to exogenously-supplied cytokines. These antibodies are thought to play a regulatory role in the intensity and duration of immune response. Interferon (IFN) beta has been shown to attenuate both relapsing-remitting multiple sclerosis (MS) and secondary progressive MS in several well-powered, randomized, controlled clinical trials. IFN therapy can induce the production of anti-IFN neutralizing antibodies (NAb), usually in the second 6 months of treatment, in 3 to 45% of treated patients. This variation in the proportion of NAb-positive patients is probably due to the immunogenicity of different formulations of IFN beta, as well as the assay used, which are not currently standardized. The occurrence of NAb appears to be directly correlated with the dose of therapeutic IFN administered, up to a certain dose threshold. If the dose is increased beyond this threshold, the levels of NAb decrease. The biological significance of anti-IFN NAb is not yet known, nor has it been proven conclusively that they affect the clinical response to IFN beta therapy. The presence of NAb is therefore not an indication that treatment should be changed. Indeed, any treatment decision should be based only on the clinical response to therapy.

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Section: Quantitation (If Appropriate)mentioning

confidence: 99%

“…Many factors, between laboratories as well as within a laboratory, can contribute to variations in IFN a potency as determined by the CPE-inhibition assay (Table 8) (37,38). The nature of the cells (diploid vs. transformed, human vs. animal, or primary cul- tures vs. a cell line); the virus (eg, encephalomyocarditis vs. vesicular stomatitis virus); and the endpoint system (eg, visual inspection vs. a spectrophotometric endpoint) are all factors that can contribute to differences in the determination of potency.…”

Section: Quantitation (If Appropriate)mentioning

confidence: 99%

Approval Standards for Alfa Interferon Subtypes

Trotta¹,

Antonelli²,

Bausch³

et al. 2000

Drug Information J

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The quality and potency of recombinant proteins is peculiarly dependent on numerous factors in the manufacturing process. The producing strain, the plasmid, and the production process from fermentation to final purification have a profound influence on the impurities in the drug substance as well as on the structure of the compound, particularly its tertiary structure, which has implications for receptor-binding, mechanism of action and, ultimately, clinical safety and eflcacy. The molecule produced from a defined strain and process must also be fully characterized to determine whether impurities or compounds related to the encoded protein may be present that can affect quality, safety, efficacy, and antigenicity. Even when a new product meets specifications comparable to those of an approved reference product, however; the active substance and the profile of impurities will probably differ since both the nature of the active substance and the impurity profile are process-dependent. Since many variables can affect biologic activity as well as clinical safety and eflcacy, controlled clinical trials must be conducted to establish safety and efficacy. This review describes scientific issues regarding production, characterization, quality assurance, biologic activity, and clinical safety and efficacy, which relate specifically to recombinant alfa interferons but also have broader application for approval standards for other recombinant proteins produced by a new manufacturer using a completely different manufacturing process.

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Assay of Interferons

Cited by 8 publications

References 80 publications

HuIFN-γ Antiviral Activity Correlates with Immunological Reactivity in a Double-Monoclonal Antibody Radiometrie Assay

HuIFN-γ Antiviral Activity Correlates with Immunological Reactivity in a Double-Monoclonal Antibody Radiometrie Assay

Anti-interferon antibodies in multiple sclerosis. Molecular basis and their impact on clinical efficacy

Approval Standards for Alfa Interferon Subtypes

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