Cell-Based Assay Services: Cytokine/Chemokine Bioactivity & Antiviral Assays

Cell-based assay tools are key to understanding cellular mechanisms in a biologically relevant context. PBL offers a targeted portfolio of cell-based assay services to provide you with the most relevant information and facilitate advancement of your research.


Whatever your cell-based study needs, PBL will work with you to determine the most suitable assay program to meet your goals. PBL's services team is a trusted partner of midsize and major biotech and pharma companies worldwide.


Selected capabilities:

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Cytokine/Chemokine Bioactivity Assays


Proliferation & Anti-Proliferation Assays

Growth promotion and inhibition assays are often used to measure cytokine and drug activity profiles. Such Proliferation and Anti-Proliferation (AP) assays utilize a variety of cell lines and protein or small molecule stimuli to address specific applications and clinical indications. EC50 or IC50 results are provided.


Figure 1 shows OVCAR-3 grown in the presence of IFN-alpha. Cellular anti-proliferation was quantified using soluble tetrazolium reagent. Figure 2 shows TF-1 grown in the presence of GM-CSF. Cellular proliferation was quantified using soluble tetrazolium reagent. For both graphs, the quantity of reduced reagent product is directly proportional to viable cell number.


For more information on PBL's Proliferation & Anti-Proliferation Assay Services, click here.

Figures 1 and 2. Growth Inhibition and Promotion Assays

Growth Inhibition and Promotion Assays

Cytokine Secretion Assays

Accurate measurement of the ability of a sample to induce cytokine production and/or release from cell lines or isolated donor cells is the standard assay for certain applications, such as measurement of IL-18 activity.


Figure 3 shows a natural killer cell model, NK-92, stimulated to produce IFN-Gamma by incubation with Type I IFNs. The data is graphed as a function of IFN-alpha concentration in the bioassay.


For more information on PBL's Cytokine Secretion Assay Service, click here.

Figure 3. Cytokine Secretion Assay

Cytokine Secretion Assay

Antiviral Assays


Cytopathic Effect Inhibition (CPE) Assays

  • Frequently used systems:
    • Human A549 / EMCV
    • Bovine MDBK
    • Mouse L929 / VSV
  • High level of assay sensitivity and accuracy

The standard bioassay used to determine the biological activity of interferon (IFN) encompasses measurement of the protection of cells from the cytopathic effect (CPE) of certain viruses. CPE assay services may be used to measure the antiviral activity of IFN-α, β, ω, γ, and λ in human samples, as well as in a variety of other species, and in multiple matrices.


CPE assays are inherently complex due to the metabolic state of cells, virus replication, and the ability of IFN to protect cells. Our years of knowledge and expertise in CPE assays will reduce variability and provide you with reproducible quality results.


Results are provided either as a graphical representation of dye binding which allows slope and parallel line analysis, or visually determined from microscopic examination of the CPE and determination of the dilution of test samples which protects 50% of the cells.


Figure 4 to the right shows IFN-beta titrated in a CPE assay on A549 cells with EMCV. In this antiviral assay, the EC50 is approximately 1 unit/ml of interferon. Units of IFN activity were determined colorimetrically with respect to an international reference standard for human IFN.


For more information on PBL's CPE Assay Service, click here. 


Figure 4. Human IFN-Beta AVA Standard in CPE Assay

Cytopathic Effect Inhibition Assay

Neutralizing Antibody Assays

  • Suitable for serum, plasma, cell culture media, or tissue culture media samples

The standard method of accurately determining whether a sample may inhibit the biological activity of cytokines is the neutralization assay. Results, provided either as a visual read or in a graphical format, reveal the ability of a sample to block the activity of IFN added at a specific concentration which provides 100% cell protection.


May be used as an anti-drug antibody (ADA) assay for certain therapeutics.


Figure 5 to the right shows representative neutralization curves of two different MAbs to IFN in a CPE assay to determine neutralization titer. One neutralization unit (NU) is the amount of antiserum or antibody (NAb) required to neutralize 1 unit of human IFN to a 50% endpoint. NU are determined with respect to the international reference standard.


For more information on PBL's Neutralizing Antibody Assay Service, click here.

Figure 5. Monoclonal Antibody Titration (Neutralizing Antibody Assay)

Neutralizing Antibody Assay

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