Recombinant Human IL-21R

Recombinant Human IL-21R is primarily used in research to study and modulate the IL-21/IL-21R signaling pathway, which is crucial for immune cell development, function, and antitumor responses. Its applications include acting as a decoy receptor to inhibit IL-21 signaling, probing receptor-ligand interactions, and validating therapeutic strategies targeting this pathway.

Key scientific applications and rationales for using recombinant human IL-21R:

• Blocking IL-21 Signaling: Recombinant IL-21R can function as a soluble decoy receptor, binding IL-21 and preventing it from activating cell-surface IL-21 receptors. This is useful for dissecting the biological effects of IL-21 in vitro and in vivo, such as inhibiting IL-21-dependent enhancement of IFN-γ secretion in NK cells.
• Studying Immune Modulation: The IL-21/IL-21R axis is central to the regulation of T cells, B cells, and NK cells, influencing their proliferation, differentiation, and cytotoxic activity. Using recombinant IL-21R allows researchers to investigate how blocking or modulating this pathway affects immune responses, including antitumor immunity and autoimmunity.
• Therapeutic Validation: Recombinant IL-21R is used to validate therapeutic approaches that target IL-21 signaling, such as in cancer immunotherapy or autoimmune disease models. For example, blocking IL-21/IL-21R interactions can help determine the pathway’s role in disease progression or treatment response.
• Receptor-Ligand Interaction Studies: Recombinant IL-21R is valuable for biochemical and structural studies, enabling precise characterization of IL-21 binding and downstream signaling events.
• Assay Development: It is used in cell-based and biochemical assays to quantify IL-21 activity, screen for inhibitors, or develop diagnostic tools.

Summary of benefits:

• Enables precise dissection of IL-21-mediated effects on immune cells.
• Facilitates the development and validation of IL-21/IL-21R-targeted therapies.
• Provides a tool for neutralizing IL-21 in experimental systems, allowing for controlled studies of cytokine function.

In summary, recombinant human IL-21R is a versatile reagent for immunological research, particularly in studies of cytokine signaling, immune modulation, and therapeutic development targeting the IL-21 pathway.

Recombinant Human IL-21R can be used as a standard for quantification or calibration in ELISA assays, provided it is validated for this purpose and matches the assay’s requirements. The suitability depends on the protein’s purity, form, and compatibility with the antibodies used in your ELISA.

Key considerations:

• Validation for ELISA Standard Use: Some recombinant IL-21R proteins are specifically recommended for use as ELISA standards, especially when supplied with carrier proteins like BSA to enhance stability and reproducibility. However, not all recombinant proteins are validated for quantitative ELISA use; some are intended only for functional assays or bioactivity studies.

• Protein Fragment and Epitope Recognition: The recombinant IL-21R you referenced is a fragment (amino acids 20–236). It is essential that this fragment contains the epitopes recognized by both the capture and detection antibodies in your ELISA. If the antibodies target regions outside this fragment, the standard may not be detected accurately.

• Purity and Endotoxin Levels: High purity (>95%) and low endotoxin levels (<1 EU/µg) are important for quantitative standards to avoid interference in the assay.

• Carrier Protein: Standards with carrier proteins (e.g., BSA) are generally preferred for ELISA calibration due to improved stability and reduced adsorption to plasticware.

• Assay-Specific Calibration: Commercial ELISA kits for IL-21R typically include a recombinant IL-21R standard that has been validated for use with the kit’s antibodies and protocol. If you use a recombinant IL-21R not supplied with the kit, you must validate its performance by generating a standard curve and confirming parallelism with the kit standard.

Best Practices:

• Confirm that your recombinant IL-21R matches the immunoreactivity required for your ELISA (i.e., the same isoform, fragment, and post-translational modifications as the native protein in your samples).
• Run a standard curve with your recombinant IL-21R and compare it to the kit standard, if available, to ensure accurate quantification.
• Use appropriate diluents and blocking buffers to minimize matrix effects and non-specific binding.

Summary Table: Recombinant IL-21R Use as ELISA Standard

Conclusion:
You can use recombinant human IL-21R as a standard for ELISA quantification if it is validated for this purpose and matches the assay’s antibody specificity. For best results, use a standard provided or recommended by the ELISA kit manufacturer, or thoroughly validate your recombinant protein in your assay system.

Recombinant Human IL-21R has been validated for several key applications in published research, primarily in the context of immunology and cancer biology.

Validated Applications:

• Functional Assays: Recombinant IL-21R is used to assess its ability to inhibit IL-21-dependent biological activities, such as the enhancement of IFN-γ secretion in NK-92 human natural killer lymphoma cells. This demonstrates its utility in studying IL-21 signaling and receptor-ligand interactions.

• ELISA (Enzyme-Linked Immunosorbent Assay): IL-21R is commonly used as a capture or detection reagent in ELISA to quantify IL-21 or to study IL-21/IL-21R interactions.

• Western Blot: Recombinant IL-21R can be used as a positive control or for detection of IL-21R protein in cell lysates, validating antibody specificity and protein expression.

• Blocking Assays: It is employed to block IL-21 signaling in vitro, helping to dissect the functional consequences of IL-21/IL-21R engagement in immune cell populations.

• Immunohistochemistry: Recombinant IL-21R is used to validate antibody specificity and to study tissue distribution of IL-21R expression.

Research Applications:

• Adoptive T Cell Therapy: Engineered IL-21R has been used to arm TCR-engineered T cells, enhancing their proliferation, memory differentiation, and antitumor function in vitro and in vivo, particularly in hepatocellular carcinoma models.

• Cancer Immunotherapy: Recombinant IL-21R is involved in studies combining IL-21 or IL-21R signaling with immune checkpoint blockade (e.g., PD-1, CTLA-4, Tim-3, Lag-3) to improve antitumor responses.

• Leukemia and Lymphoma Research: Elevated IL-21R expression has been observed in certain leukemia and lymphoma samples, and recombinant IL-21R is used to study its role in disease progression and response to therapy.

• Acute Myeloid Leukemia (AML): IL-21/IL-21R signaling has been shown to sensitize AML stem cells to cytarabine and CAR T cell therapy, with recombinant IL-21R used to dissect these mechanisms.

Summary Table of Validated Applications

These applications are supported by multiple peer-reviewed studies and product validation data, confirming the versatility of recombinant human IL-21R in both basic and translational research.

To reconstitute and prepare Recombinant Human IL-21R protein for cell culture experiments, follow these best-practice steps based on current protocols and technical datasheets:

1. Centrifuge the vial
   Briefly centrifuge the lyophilized protein vial before opening to ensure all material is at the bottom.

2. Reconstitution

   • Add sterile distilled water to the vial to achieve a final concentration of 0.1–0.5 mg/mL (100–500 μg/mL).
   • Gently mix by swirling or slow pipetting down the side of the vial. Do not vortex or pipette vigorously to avoid protein denaturation.
   • Allow several minutes for complete dissolution.

3. Carrier Protein Addition (Optional but Recommended for Storage/Handling)

   • For improved stability, especially if you plan to store aliquots or use the protein over several days, add a carrier protein such as 0.1% BSA, 5% HSA, 10% FBS, or 5% trehalose.
   • This is particularly important if the protein will undergo freeze-thaw cycles.

4. Aliquoting and Storage

   • Aliquot the reconstituted protein into single-use volumes to avoid repeated freeze-thaw cycles.
   • Store aliquots at –20 °C for up to 3 months or at 2–8 °C for up to 1 week.
   • Avoid repeated freeze/thaw cycles, as this can reduce protein activity and stability.

5. Preparation for Cell Culture

   • Before adding to cell culture, dilute the reconstituted protein to the desired working concentration using cell culture medium or buffered solution (e.g., PBS) containing a carrier protein (such as BSA or FBS) to minimize adsorption and loss.
   • Ensure the final buffer is compatible with your cell culture system and is low in endotoxin.

Summary Table: Recombinant Human IL-21R Reconstitution

Additional Notes:

• Always use sterile technique and wear appropriate PPE (lab coat, gloves) when handling recombinant proteins.
• If the protein is to be used for functional assays (e.g., ligand binding, inhibition), confirm activity after reconstitution as per your experimental requirements.

If your specific application requires a different buffer or concentration, adjust accordingly, but always avoid harsh mixing and repeated freeze-thaw cycles to preserve protein integrity.