Detection of serum interferon-α by dissociation-enhanced lanthanide fluoroimmunoassay

Cytokines as Biomarkers in Systemic Lupus Erythematosus: Value for Diagnosis and Drug Therapy

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease. The disease is characterized by activation and dysregulation of both the innate and the adaptive immune systems. The autoimmune response targets self-molecules including cell nuclei, double stranded DNA and other intra and extracellular structures. Multiple susceptibility genes within the immune system have been identified, as well as disturbances in different immune pathways. SLE may affect different organs and organ systems, and organ involvement is diverse among individuals. A universal understanding of pathophysiological mechanism of the disease, as well as directed therapies, are still missing. Cytokines are immunomodulating molecules produced by cells of the immune system. Interferons (IFNs) are a broad group of cytokines, primarily produced by the innate immune system. The IFN system has been observed to be dysregulated in SLE, and therefore IFNs have been extensively studied with a hope to understand the disease mechanisms and identify novel targeted therapies. In several autoimmune diseases identification and subsequent blockade of specific cytokines has led to successful therapies, for example tumor necrosis factor-alpha (TNF-α) inhibition in rheumatoid arthritis. Authors of this review have sought corresponding developments in SLE. In the current review, we cover the actual knowledge on IFNs and other studied cytokines as biomarkers and treatment targets in SLE.

Interferon-β therapy prolongs survival in rhesus macaque models of Ebola and Marburg hemorrhagic fever

There is a clear need for novel, effective therapeutic approaches to hemorrhagic fever due to filoviruses. Ebola virus hemorrhagic fever is associated with robust interferon (IFN)-α production, with plasma concentrations of IFN-α that greatly (60- to 100-fold) exceed those seen in other viral infections, but little IFN-β production. While all of the type I IFNs signal through the same receptor complex, both quantitative and qualitative differences in biological activity are observed after stimulation of the receptor complex with different type I IFNs. Taken together, this suggested potential for IFN-β therapy in filovirus infection. Here we show that early postexposure treatment with IFN-β significantly increased survival time of rhesus macaques infected with a lethal dose of Ebola virus, although it failed to alter mortality. Early treatment with IFN-β also significantly increased survival time after Marburg virus infection. IFN-β may have promise as an adjunctive postexposure therapy in filovirus infection.

A time-resolved fluorescence immunoassay (DELFIA) increases the sensitivity of antigen-driven cytokine detection

In an effort to improve the quantification of the low levels of cytokines released in response to antigenic stimulation of T cells, a sandwich dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA) was developed and compared to a standard sandwich ELISA. The DELFIA enhanced the sensitivity of a mouse IL-2 assay 8- to 27-fold, and a human GM-CSF assay 10-fold, as compared to colorimetric ELISA. The increase in sensitivity allows for the use of lower sample volumes per well, and the ability to run more assays per supernatant sample. This sensitive, nonisotopic alternative to other cytokine detection methods will be useful for those researchers wanting to quantitate low levels of antigen-driven cytokine production.

Development of a highly purified multicomponent leukocyte IFN-alpha product

A purification process was developed to obtain a human interferon- alpha (IFN-alpha) product that contains all major IFN-alpha subtypes produced by human leukocytes. The purification was accomplished by immunoaffinity chromatography using two monoclonal antibodies (mAb) and gel filtration. The process comprised two effective virus inactivation steps, solvent detergent treatment, and incubation at low pH, and the purified product was filtered with a 15-nm pore size virus removal filter. The overall yield of IFN-alpha in the process was about 60% when starting from the culture supernatant of Sendai virus-induced human leukocytes. The specific activity was about 1.0 x 10(8) IU/mg. The level of DNA and protein impurities including mouse IgG was very low. The product contained seven main subtypes: IFN-alpha 1, IFN-alpha 2, IFN-alpha 8, IFN-alpha 10, IFN-alpha 14, IFN-alpha 17, and IFN-alpha 21. The subtypes IFN-alpha 4 and IFN-alpha 7 were minor components. Reverse-phase HPLC indicated a constant subtype composition for the product from batch to batch. Stabilization of the pure IFN-alpha solution with albumin and Tween 80 was compared. In virus filtration, a better yield and higher filtration capacity were obtained with Tween. The addition of albumin resulted in the formation of IFN-albumin aggregates. During long-term storage, IFN-alpha was stable in both solutions for 2 years at 2-8 degrees C. The new method makes it possible to extensively purify all major IFN-alpha subtypes and obtain a virus-safe and stable product with a constant subtype composition.

Role of sialylation in determining the pharmacokinetics of neutrophil inhibitory factor (NIF) in the Fischer 344 rat

1. Recombinant neutrophil inhibitory factor (NIF) is a glycoprotein. Its amino acid sequence remains constant and has a molecular weight of 28.9 kD. However, approximately 40% of the total molecular weight consists of glycans with variable structure. 2. The pharmacokinetics of 11 different NIF batches with varying extents and patterns of sialylation have been investigated in the Fischer 344 rat following intravenous administration. These data indicate that reducing the extent of NIF sialylation reduces the half-life of the molecule due to an increase in the systemic clearance. Also, an increase in the number of unsialylated or neutral glycans may increase the volume of distribution of NIF, although this effect is marginal. 3. Isolated perfused rat liver (IPRL) investigations have shown that sialylated NIF has a low hepatic extraction (< 1%), while asialo NIF has an extraction that is > 20-fold higher. Co-administration of asialo NIF with asialo fetuin (a protein cleared by hepatic asialoglycoprotein receptor (possibly galactose)-mediated uptake reduced the hepatic extraction of asialo NIF. 4. These data suggest that NIF molecules that have free sugar moieties (possibly galactose) interact with an asialoglycoprotein receptor (possibly galactose-mediated) in the liver (parenchymal cells/hepatocytes). Interaction with this receptor leads to cellular internalization and degradation.