Recombinant mouse fractalkine (CX3CL1) offers several compelling advantages for research applications, particularly in studies examining immune cell interactions, neuroinflammation, and tissue regeneration.

Key Research Applications

Chemotaxis and Cell Migration Studies

Recombinant mouse fractalkine effectively chemoattracts cells expressing the CX3CR1 receptor, making it ideal for migration and recruitment assays. The protein demonstrates reproducible bioactivity with well-characterized effective concentrations (ED₅₀ values of 0.03-0.12 μg/mL for chemotaxis), enabling precise experimental design and reliable quantification of cell responses.

Neuroinflammation and Microglial Regulation

Fractalkine plays a critical role in regulating microglial physiology and neuron-glia interactions. The protein is principally produced by neurons, while microglia express the functional CX3CR1 receptor. This makes recombinant fractalkine particularly valuable for investigating microglial recruitment, activation states, and their consequences in various neurological contexts.

Remyelination and Neuroprotection

Recent research demonstrates that fractalkine administration promotes oligodendrocyte regeneration and myelin formation. In demyelinating disease models, fractalkine infusion increased mature oligodendrocyte density by approximately 1.46- to 2-fold and enhanced new myelin formation by 1.8- to 2-fold, comparable to agents currently in clinical trials. The protein also reduces pro-inflammatory microglial populations while promoting remyelination in both white and grey matter.

Technical Advantages

The recombinant protein is typically produced in insect cell systems (Sf21 baculovirus-derived) with high purity (>97%) and includes a C-terminal 6-His tag for easy detection and purification. This standardized production ensures batch-to-batch consistency essential for reproducible research outcomes.

Experimental Versatility

Recombinant mouse fractalkine is suitable for multiple assay formats including bioassays, binding assays, and ELISA applications, providing flexibility across different experimental designs and research questions.

You can use recombinant mouse Fractalkine (CX3CL1) protein as a standard for quantification or calibration in ELISA assays, provided that the recombinant protein is well-characterized, matches the relevant epitope(s) recognized by your assay antibodies, and is supplied in a quantifiable, pure form.

Essential context and supporting details:

• Recombinant standards are commonly used in ELISA kits for quantification of mouse Fractalkine/CX3CL1. Many commercial ELISA kits use recombinant mouse Fractalkine produced in insect cells (e.g., Sf21) as their standard, and these standards are serially diluted to generate a calibration curve.
• The standard must be compatible with your assay antibodies. Most sandwich ELISAs use antibodies that recognize the chemokine domain of Fractalkine. If your recombinant protein is fragmented, you must confirm that the fragment contains the relevant epitope(s) recognized by both the capture and detection antibodies in your assay.
• Purity and quantification: The recombinant standard should be highly purified and supplied with a known concentration, ideally verified by protein assay or absorbance at 280 nm. Impurities or inaccurate concentration can compromise quantification.
• Fragmented vs. full-length protein: If your recombinant Fractalkine is a fragment (not full-length), ensure that the fragment includes the region detected by your ELISA antibodies. Many kits use the chemokine domain (N-terminal region) as the standard, as this is the biologically active and immunodominant portion. If your fragment lacks the relevant domain, it may not be suitable as a standard.
• Validation: It is best practice to validate the recombinant standard in your specific ELISA system. This includes confirming parallelism between the standard curve and sample dilution curves, and ensuring recovery and linearity.

Additional relevant information:

• Standard curve preparation: Always prepare a fresh standard curve for each assay run, using serial dilutions of the recombinant protein in the same buffer as your samples.
• Documentation: Record the lot number, concentration, and source of your recombinant standard for reproducibility and troubleshooting.
• Limitations: Recombinant standards may differ from endogenous protein in post-translational modifications or folding, which can affect antibody recognition in rare cases. If your assay is highly sensitive to such differences, consider validating with endogenous protein or using spike-and-recovery experiments.

Summary Table: Recombinant Fractalkine Standard Use in ELISA

If your recombinant mouse Fractalkine (fragmented) meets these criteria, it can be used as a standard for ELISA quantification. If uncertain about epitope compatibility, consult the antibody datasheets or perform a pilot assay.

Applications of Recombinant Mouse Fractalkine in Published Research

Recombinant mouse fractalkine (CX3CL1) has been validated across multiple research applications, with particular emphasis on its role in neurobiology and immunology.

Bioassay Applications

The primary validated application is bioassay, where recombinant mouse fractalkine has been extensively used to assess biological activity. This includes chemotaxis assays measuring the protein's ability to attract cells expressing the CX3CR1 receptor, such as BaF3 mouse pro-B cells transfected with mouse CX3CR1. The effective dose (ED₅₀) for this chemotactic effect ranges from 0.03-0.12 μg/mL.

Binding and Receptor Studies

Recombinant fractalkine has been validated for binding assays examining receptor-ligand interactions. Research has characterized binding in cell-substrate contact zones using CX3CR1 and related chemokine receptors, providing quantitative analysis of fractalkine-receptor engagement.

Neurobiological Research

The protein has been validated in studies investigating oligodendrocyte regeneration and remyelination. Fractalkine infusion in demyelinating mouse models increased mature oligodendrocyte numbers by approximately 1.46- to 2-fold and enhanced new myelin formation by 1.8- to 2-fold compared to vehicle controls. These findings demonstrate fractalkine's pro-regenerative role in central nervous system (CNS) contexts.

Microglial and Immune Function Studies

Recombinant fractalkine has been used to study microglial physiology and neurotoxicity regulation, as well as macrophage polarization in contact hypersensitivity models. The protein has also been applied in investigating the fractalkine-CX3CR1 axis in transplant rejection and ischemia-reperfusion injury contexts.

ELISA and Immunoassay Applications

The protein is suitable for fractalkine ELISA and immunoassay applications in mouse model studies, enabling quantitative detection and analysis of fractalkine-mediated biological responses.

To properly reconstitute and prepare Recombinant Mouse Fractalkine (Fragmented) protein for cell culture experiments, follow these general best practices based on manufacturer guidelines and scientific protocols:

1. Preparation Before Reconstitution

• Centrifuge the lyophilized protein vial briefly (e.g., 10–15 seconds at low speed) before opening to ensure all powder is at the bottom.

2. Reconstitution

• Reconstitute the protein in sterile distilled water or sterile PBS (phosphate-buffered saline) to a final concentration typically between 0.1–0.5 mg/mL. Some protocols allow up to 1.0 mg/mL depending on the product.
• Gently pipette up and down to dissolve the protein. Do not vortex or shake vigorously, as this may denature the protein or cause foaming.

3. Carrier Protein (Optional)

• For cell culture, it is often recommended to add a carrier protein such as 0.1% BSA (bovine serum albumin) or 5% HSA (human serum albumin) to stabilize the protein and reduce non-specific binding.
• If performing serum-free culture or in vivo experiments, use trehalose (5–10%) as a stabilizer instead of BSA/HSA.

4. Aliquoting and Storage

• Aliquot the reconstituted protein into small volumes to minimize freeze-thaw cycles.
• For short-term use (up to 1 week), store at 2–8°C.
• For long-term storage, aliquot and store at –20°C or lower. Avoid repeated freeze-thaw cycles.
• If long-term storage is needed, consider adding 5–10% trehalose or 5–50% glycerol before freezing.

5. Use in Cell Culture

• Dilute the reconstituted protein in cell culture medium to the desired working concentration.
• Typical working concentrations for chemokines like Fractalkine in cell migration or activation assays range from 10–100 ng/mL, but optimal concentration should be determined empirically for your specific experiment.

6. Additional Notes

• Always check the product datasheet for specific instructions, as formulations may vary between suppliers.
• If the protein is carrier-free, avoid diluting below 0.1 mg/mL to prevent loss due to adsorption.

Summary Protocol:

1. Centrifuge vial.
2. Reconstitute in sterile water or PBS to 0.1–0.5 mg/mL.
3. Add 0.1% BSA (or trehalose for serum-free/in vivo use) if desired.
4. Gently mix; do not vortex.
5. Aliquot and store at 2–8°C (≤1 week) or –20°C (≤3 months).
6. Dilute in culture medium for use.

Always refer to the specific product manual for any unique requirements.