Name: Interleukin-21 (Human, Recombinant)
Brand: Molecular Depot
SKU: B2010308
Price: 495.00 USD
Availability: InStock

<h2 data-section-id="f727ot" data-start="0" data-end="41">What are interferons and interleukins?</h2>
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Interferons (IFN-alpha, IFN-beta, IFN-gamma) and interleukins (IL-1 through IL-18) are signaling cytokines that direct immune cell communication, antiviral response, and inflammation. Related entities include tumor necrosis factor (TNF-alpha), colony-stimulating factors (G-CSF, GM-CSF), Janus kinase (JAK) signaling, and T-cell, NK-cell, and macrophage activation assays.
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<h2 dir="ltr">What you'll find in this category: </h2>
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Antiviral Defense Modulators: Premium interferons prepared to study cellular resistance mechanisms and viral replication paths.
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Leukocyte Communication Links: Pure interleukins designed to direct immune cell activation, differentiation, and crosstalk.
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Immune Response Standards: Batch-validated signaling tools built to maintain steady, predictable baselines in co-culture models.
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<h2 data-section-id="1p9v7w8" data-start="587" data-end="632">How to choose interferons and interleukins</h2>
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Species and isoform match
Confirm the protocol calls for human, mouse, or rat recombinant protein and the correct isoform (e.g., IFN-gamma vs. IFN-alpha2a, IL-2 vs. IL-15). A mismatched species cytokine will not activate the intended receptor in most cell lines.
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Carrier protein presence
Carrier-free formats (no BSA) are preferred for applications where trace bovine protein could confound downstream assays, such as ELISA development or animal-component-free (ACF) stem cell culture. Carrier-added formats improve stability for general cell culture supplementation.
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Endotoxin level
Endotoxin-free or low-endotoxin (typically &lt;0.1 ng per microgram of protein) preparations matter for immune cell assays, since lipopolysaccharide contamination can independently activate macrophages and skew interleukin readouts.
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Activity verification (bioassay vs. SDS-PAGE)
Look for lot-specific bioactivity data (e.g., ED50 in a proliferation or reporter assay), not only purity by SDS-PAGE, when reproducibility across lots is critical for a multi-month study.
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<h2 data-section-id="1fljvas" data-start="2347" data-end="2372">Specifications context</h2>
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Concentrations for cytokine stimulation assays are typically expressed in ng/mL, with working ranges from 0.1 ng/mL to 100 ng/mL depending on the receptor's sensitivity and the readout (proliferation vs. reporter gene). Specific activity is reported in units/mg or IU/mg for interferons, following international reference standards used to calibrate antiviral potency. As of 2026, labs increasingly request carrier-free, endotoxin-tested lots when cytokines feed into single-cell or multi-omics workflows where background activation must be minimized.
For related signaling reagents, see Epidermal Growth Factors (EGF), Transforming Growth Factors, Tumor Necrosis Factors (TNF-alpha), Fibroblast Growth Factors (FGF), and the broader Growth Factors &amp; Hormones category.
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Interferons & Interleukins

Molecular Depot

Key Specifications

Interleukin-21 (Human, Recombinant)

Interleukin-21 (Human, Recombinant) by Molecular Depot is highly pure recombinant human interleukin-21 (IL-21) expressed in E. coli. IL-21 is a class 1 cytokine produced by activated CD4+ T cells that stimulates T, B and NK cells, enhancing proliferation and effector function. It is used in B-cell differentiation and antibody research, follicular helper T-cell studies, NK and CD8 T-cell expansion and as a standard in IL-21 immunoassays. Each unit contains 10 µg. MBP supplies Molecular Depot research reagents to research labs in the United States, Canada and worldwide.