Recombinant Human APRIL

Recombinant human APRIL (A Proliferation-Inducing Ligand) offers several compelling advantages for research applications, particularly in immunology and disease modeling studies.

Scientific Advantages

Precision and Reproducibility

Recombinant human APRIL provides consistent, high-purity protein suitable for rigorous experimental work. Unlike native sources, recombinant production ensures batch-to-batch reproducibility, which is essential for obtaining reliable and comparable results across multiple experiments and research groups.

Well-Characterized Biological Activity

APRIL is a member of the TNF superfamily with clearly defined mechanisms of action. The protein specifically interacts with two key receptors—BCMA (B-cell maturation antigen) and TACI (Transmembrane Activator and CAML-interactor)—allowing you to study targeted immune signaling pathways. When APRIL binds to BCMA, it triggers robust survival signals through NF-κB pathway activation and upregulates anti-apoptotic proteins like Mcl-1, while TACI signaling promotes Blimp-1 expression for maintaining plasma cell identity.

Research Applications

B Cell and Plasma Cell Studies

Recombinant APRIL is particularly valuable for investigating long-lived plasma cell (LLPC) biology. APRIL specifically supports LLPCs through unique binding affinities distinct from other B cell developmental stages. You can use recombinant APRIL to examine plasma cell survival, proliferation, and antibody production in controlled in vitro settings.

Autoimmune Disease Modeling

APRIL plays a critical role in autoimmune pathogenesis, making recombinant protein essential for disease research. Studies demonstrate that APRIL overexpression significantly reduces collagen-induced arthritis severity in mice. Additionally, APRIL uniquely promotes IL-10 production and enhances regulatory B cell (Breg) functions in human B cells, unlike BAFF. This makes recombinant APRIL valuable for investigating regulatory immune mechanisms and testing potential therapeutic interventions.

Therapeutic Development

Recombinant APRIL enables screening of neutralizing antibodies and receptor antagonists for treating conditions like systemic lupus erythematosus (SLE) and IgA nephropathy (IgAN). Preliminary clinical trial data indicate that APRIL inhibition can reduce proteinuria and slow kidney disease progression in IgAN by acting at upstream pathogenic levels.

Experimental Flexibility

Recombinant human APRIL can be applied to multiple experimental formats including bioassays, binding assays for protein-protein interactions, apoptosis assays, and flow cytometry applications. The protein is available in various formats and expression systems, allowing you to select the most appropriate form for your specific experimental needs.

Yes, you can use Recombinant Human APRIL as a standard for quantification or calibration in your ELISA assays. Recombinant Human APRIL is routinely used as a standard in commercial ELISA kits for the quantitative measurement of human APRIL/TNFSF13 in biological samples such as serum, plasma, and cell culture supernatants. This is because recombinant proteins provide a purified, well-characterized source of the target antigen, which is essential for generating accurate standard curves.

When preparing the standard curve, it is recommended to use a purified or recombinant protein to ensure consistency and reliability. For ELISA applications, recombinant APRIL formulated with BSA is typically preferred, as BSA helps stabilize the protein and is compatible with most ELISA protocols. However, if BSA could interfere with your specific assay, a carrier-free version should be used.

In summary:

• Recombinant Human APRIL is suitable and commonly used as an ELISA standard.
• Use a formulation with BSA unless BSA interferes with your assay.
• Follow the dilution and handling instructions provided by the supplier for optimal results.

Recombinant Human APRIL has been validated in published research for several key applications, primarily in the fields of immunology, oncology, and neurobiology.

Validated Applications in Published Research:

• In vitro bioassays:
  APRIL is widely used to assess its biological activity on immune cells, particularly for supporting the survival and differentiation of plasma cells (PCs) and plasmablasts (PBs). It has been shown to activate signaling pathways such as ERK, p38, JNK, and NF-κB, and to promote the survival of antibody-secreting cells in culture.

• Cell culture studies:
  Recombinant APRIL is used to stimulate cell proliferation, especially in B cell and plasma cell models, and to study its effects on immune cell maturation and function. It is also used to investigate the impact of APRIL on tumor cell growth and survival in cancer research.

• Apoptosis assays:
  APRIL has been validated for use in apoptosis assays, where it is tested for its ability to protect cells from programmed cell death, particularly in B cell populations.

• Protein-protein interaction and binding assays:
  It is used in binding assays to study interactions with its receptors (BCMA, TACI) and other ligands, as well as to characterize its molecular partners.

• ELISA standard:
  Recombinant APRIL serves as a standard in ELISA-based quantification assays for detecting APRIL levels in biological samples.

• Biomarker studies:
  APRIL is investigated as a biomarker for tumor proliferation and certain autoimmune diseases, with elevated levels observed in serum or tissues of affected patients.

• Neurite outgrowth assays:
  In neurobiology, APRIL has been validated for promoting neurite outgrowth in developing neurons, demonstrating its role in axonal growth and neural development.

• Screening and release assays:
  It is used in screening assays for antibodies or compounds that block APRIL signaling, relevant for therapeutic development.

Additional Context:

• Immunotherapy research:
  Recombinant APRIL is a tool for exploring new immunotherapeutic strategies, including modulation of immune responses in cancer and autoimmune diseases.

• Mechanistic studies:
  It is used to dissect signaling pathways and gene expression programs downstream of APRIL engagement in immune cells.

• SDS-PAGE control:
  APRIL is sometimes used as a control protein in SDS-PAGE to verify protein integrity and molecular weight.

Summary Table of Validated Applications

These applications are supported by peer-reviewed studies and product validation data, demonstrating the versatility of recombinant human APRIL in both basic and translational research contexts.

To reconstitute and prepare Recombinant Human APRIL protein for cell culture experiments, follow these general guidelines based on standard protocols and manufacturer recommendations:

Reconstitution Steps

1. Centrifuge the Vial: Before opening, briefly centrifuge the lyophilized protein vial (or tap it gently) to ensure all powder is collected at the bottom.

2. Equilibrate to Room Temperature: Allow both the vial and the reconstitution buffer to reach room temperature before proceeding.

3. Choose the Correct Buffer:

   • If the protein is supplied with a carrier protein (such as BSA), reconstitute in sterile PBS containing at least 0.1% human or bovine serum albumin (BSA).
   • If the protein is carrier-free, reconstitute in sterile PBS alone.

4. Reconstitution Concentration: Most protocols recommend reconstituting the lyophilized protein at a concentration of 100 μg/mL. Adjust the volume of buffer accordingly based on the amount of protein in the vial.

5. Gentle Mixing: Add the buffer to the vial and allow it to reconstitute for 15–30 minutes at room temperature with gentle agitation (do not shake vigorously to avoid foaming and protein denaturation).

6. Aliquot and Store: Once fully dissolved, aliquot the protein into volumes greater than 20 μL and store at –20°C or colder. Avoid repeated freeze-thaw cycles.

Additional Notes

• For carrier-free proteins, if long-term storage is needed, consider adding a stabilizer such as trehalose (5–50% final concentration) before aliquoting and freezing.
• For serum-free or in vivo experiments, avoid using animal-derived carrier proteins (like BSA) and use alternatives such as human serum albumin (HSA) or trehalose as stabilizers.
• Always refer to the Certificate of Analysis (CoA) or product insert for specific instructions, as formulations may vary between manufacturers.

Example Protocol

• Protein: Recombinant Human APRIL (with carrier)
• Reconstitution Buffer: Sterile PBS + 0.1% BSA
• Concentration: 100 μg/mL
• Mixing: 15–30 min at room temperature, gentle agitation
• Storage: Aliquot and store at –20°C or colder

Following these steps will help ensure optimal activity and stability of the recombinant protein for your cell culture experiments.