Interferon antibodies in patients with infectious diseases. Anti-interferon antibodies

Diagnostic Accuracy of Methods for Detection of Antibodies against Type I Interferons in Patients with Endocrine Disorders

Autoantibodies against type 1 interferons (IFN-I) are a highly specific marker for type 1 autoimmune polyglandular syndrome (APS-1). Moreover, determination of antibodies to omega-interferon (IFN-ω) and alpha2-interferon (IFN-α2) allows a short-term diagnosis in patients with isolated and atypical forms of APS-1. In this study, a comparison of three different methods, namely multiplex microarray-based, cell-based and enzyme-linked immunosorbent assays for detection of antibodies against omega-interferon and alpha2-interferon, was carried out. A total of 206 serum samples from adult patients with APS-1, APS-2, isolated autoimmune endocrine pathologies or non-autoimmune endocrine disorders, and healthy individuals were analyzed. In the APS-1 patient cohort (n = 18), there was good agreement between the results of anti-IFN-I antibody tests performed by three methods, with 100% specificity and sensitivity for microarray-based assay. Although only the cell-based assay can determine the neutralizing activity of autoantibodies, the microarray-based assay can serve as a highly specific and sensitive screening test to identify anti-IFN-I antibody positive patients.

Multiplex Autoantibody Detection in Patients with Autoimmune Polyglandular Syndromes

The diagnosis of autoimmune polyglandular syndrome (APS) types 1/2 is difficult due to their rarity and nonspecific clinical manifestations. APS-1 development can be identified with assays for autoantibodies against cytokines, and APS-2 development with organ-specific antibodies. In this study, a microarray-based multiplex assay was proposed for simultaneous detection of both organ-specific (anti-21-OH, anti-GAD-65, anti-IA2, anti-ICA, anti-TG, and anti-TPO) and APS-1-specific (anti-IFN-ω, anti-IFN-α-2a, and anti-IL-22) autoantibodies. Herein, 206 serum samples from adult patients with APS-1, APS-2, isolated autoimmune endocrine pathologies or non-autoimmune endocrine pathologies and from healthy donors were analyzed. The prevalence of autoantibodies differed among the groups of healthy donors and patients with non-, mono- and multi-endocrine diseases. APS-1 patients were characterized by the presence of at least two specific autoantibodies (specificity 99.5%, sensitivity 100%). Furthermore, in 16 of the 18 patients, the APS-1 assay revealed triple positivity for autoantibodies against IFN-ω, IFN-α-2a and IL-22 (specificity 100%, sensitivity 88.9%). No anti-cytokine autoantibodies were found in the group of patients with non-APS-1 polyendocrine autoimmunity. The accuracy of the microarray-based assay compared to ELISA for organ-specific autoantibodies was 88.8-97.6%. This multiplex assay can be part of the strategy for diagnosing and predicting the development of APS.

Detection of anti-cytokine antibodies and their clinical relevance

Cytokines regulate many aspects of cell growth and differentiation and play pivotal roles in the orchestration of immune defence against invading pathogens. Though 'self' proteins, they are potentially immunogenic and can give rise to anti-cytokine autoantibodies (aCA). The main foci of the article are a critical summary of the various methodologies applied for detecting and measuring aCA and a broad review of studies of the occurrence, characterization and clinical relevance of aCA in normal healthy individuals, patients with autoimmune diseases or microbial infections and aCA in patients whose disease is treated with recombinant cytokine products. The need for technical and methodological improvement of assays, including validation and standardization, together with approaches to harmonize calculation and reporting of results is also discussed.

Interferons, interferon-like cytokines, and their receptors

Recombinant interferon-alpha (IFN-alpha) was approved by regulatory agencies in many countries in 1986. As the first biotherapeutic approved, IFN-alpha paved the way for the development of many other cytokines and growth factors. Nevertheless, understanding the functions of the multitude of human IFNs and IFN-like cytokines has just touched the surface. This review summarizes the history of the purification of human IFNs and the key aspects of our current state of knowledge of human IFN genes, proteins, and receptors. All the known IFNs and IFN-like cytokines are described [IFN-alpha, IFN-beta, IFN-epsilon, IFN-kappa, IFN-omega, IFN-delta, IFN-tau, IFN-gamma, limitin, interleukin-28A (IL-28A), IL-28B, and IL-29] as well as their receptors and signal transduction pathways. The biological activities and clinical applications of the proteins are discussed. An extensive section on the evolution of these molecules provides some new insights into the development of these proteins as major elements of innate immunity. The overall structure of the IFNs is put into perspective in relation to their receptors and functions.

Bioequivalence and the immunogenicity of biopharmaceuticals

The expiry of the first patents for recombinant-DNA-derived biopharmaceuticals will open the possibility of marketing generics, if they can be shown to be essentially similar to the innovator product. However, as shown by the problem of immunogenicity, the properties of biopharmaceuticals are dependent on many factors, including downstream processing and formulation. Products from different sources cannot be assumed to be bioequivalent, even if identical genes are expressed in the same host cells and similar production methods are used. Some of the influencing factors are still unknown, which makes it impossible to completely predict biological behaviour, such as immunogenicity, which can sometimes lead to serious side effects.

Detection of anti-erythropoietin antibodies in haemodialysis patients treated with recombinant human-erythropoietin

An enzyme-immunoassay was developed to evaluate the presence of anti-erythropoietin antibodies in plasma samples obtained from renal failure patients treated with recombinant human erythropoietin (rh-EPO). The assay was specific and reproducible. Normal donors had no antibodies to EPO, while 67% of treated patients were positive to the assay. While the specificity of anti-EPO IgG antibodies was high, their affinity for the antigen was low. This finding can be explained by the very small differences in the structure of rh-EPO compared to that of natural EPO. The assay described could be useful in evaluating the long-term effects of rh-EPO treatment on the control of anaemia in renal failure patients.

Detection and characterization of antibodies to PEG-IFN-alpha2b using surface plasmon resonance

Some patients treated with type I interferon (IFN) preparations develop neutralizing antibodies that may abrogate any clinical benefit. We have a new complex of polyethylene glycol12000 and IFN-alpha2b (PEG-IFN-alpha2b) in clinical trials and need to be able to detect any antibodies formed specifically against the complex. We have, therefore, devised a method based on measurement of surface plasmon resonance (SPR) in the BIACORE 2000 apparatus. PEG-IFN-alpha2b is anchored to one flow cell on the sensor chip, IFN-alpha2b to another, and PEG to a third. A 20 microl serum sample flows in turn through the three cells, which are optically scanned. Any antibodies in the serum bind to the corresponding immobilized antigen, and a change in the optical signal is generated. With appropriate specific reagents, their immunoglobulin isotype can be similarly established. The automated assay can quickly test numerous sera. Very little serum is needed, and the assay is reliable and precise and can detect low-alphaffinity antibodies.