Recombinant Human CXCL16

Recombinant Human CXCL16 is used in research applications to study its roles in immune cell recruitment, inflammation, tissue remodeling, and disease pathogenesis. It is a chemokine that interacts with the CXCR6 receptor and is involved in attracting specific lymphocyte subsets, modulating immune responses, and influencing pathological processes in cardiovascular disease, cancer, and autoimmune disorders.

Key scientific applications and rationales include:

• Immune Cell Chemotaxis: CXCL16 is a potent chemoattractant for T cells and natural killer T (NKT) cells, making it valuable for in vitro chemotaxis assays and studies of immune cell migration during inflammation or infection.
• Inflammation and Autoimmunity: Its expression is upregulated by inflammatory cytokines (e.g., IFN-γ, TNF-α), and it plays a pro-inflammatory role in diseases such as inflammatory bowel disease and rheumatoid arthritis. Recombinant CXCL16 can be used to model these processes or test therapeutic interventions targeting the CXCL16/CXCR6 axis.
• Cardiovascular Research: CXCL16 is implicated in atherogenesis and myocardial remodeling. It acts as a scavenger receptor for oxidized LDL on macrophages and modulates matrix metalloproteinase (MMP) activity, influencing extracellular matrix turnover and fibrosis in heart failure models.
• Cancer Biology: CXCL16 promotes tumor cell proliferation, migration, and immune cell infiltration in the tumor microenvironment, making it relevant for cancer progression studies and therapeutic targeting.
• Tissue Remodeling and Fibrosis: By regulating MMP activity and collagen synthesis, CXCL16 is involved in tissue remodeling, which is critical in fibrosis and organ repair research.
• Cellular Signaling Studies: Recombinant CXCL16 can be used to activate downstream signaling pathways (e.g., MAPK, JNK, ERK) in target cells, enabling mechanistic studies of chemokine-receptor interactions.

Experimental uses of recombinant CXCL16 include:

• Chemotaxis assays to quantify immune cell migration.
• Cell signaling and proliferation assays to study downstream effects of CXCL16-CXCR6 engagement.
• Disease modeling in vitro (e.g., co-culture with cardiomyocytes, fibroblasts, or tumor cells) to dissect its role in inflammation, remodeling, or cancer.
• Therapeutic screening for agents that modulate CXCL16 activity or block its receptor.

In summary, using recombinant human CXCL16 enables controlled, reproducible studies of its biological functions and mechanisms in diverse disease contexts, supporting both basic and translational research.

Yes, recombinant human CXCL16 is specifically designed and validated for use as a standard for quantification and calibration in ELISA assays. The recombinant protein, typically expressed in E. coli, has been demonstrated to accurately quantitate both itself and naturally occurring human CXCL16.

Validation and Performance

The recombinant human CXCL16 standards included in commercial ELISA kits undergo rigorous validation to ensure reliable quantification. When tested against natural human CXCL16, the standard curves generated with recombinant protein produce linear curves that are parallel to those obtained with naturally occurring CXCL16, confirming the suitability of the recombinant standard for measuring endogenous protein levels.

Precision and Accuracy

The recombinant standards demonstrate excellent precision characteristics. Intra-assay precision (within a single assay) typically shows coefficient of variation (CV) values below 5%, while inter-assay precision (between separate assays) generally remains below 10%. Recovery studies across various biological matrices—including cell culture media, serum, and plasma—consistently show recovery rates between 93-113%, indicating that the recombinant standard performs reliably across different sample types.

Practical Application

The recombinant human CXCL16 standard is supplied pre-titered and optimized for use in sandwich ELISA formats. Each lot is quality-controlled and validated to ensure lot-to-lot consistency, allowing you to generate accurate standard curves for quantifying CXCL16 in your samples. The standard is typically reconstituted according to kit-specific protocols and used to establish the dose-response relationship necessary for determining unknown sample concentrations.

Recombinant Human CXCL16 has been validated for several applications in published research, including ELISA, functional assays, mass spectrometry characterization, immunofluorescence, and in vivo functional studies.

Key validated applications and research uses include:

• ELISA (Enzyme-Linked Immunosorbent Assay): Used to quantify CXCL16 levels in biological samples, supporting studies of its expression in disease and inflammation.
• Functional Assays: Demonstrated activity in chemotaxis and cell migration assays, particularly for T cells and NKT cells, and in inhibition of growth factor-induced proliferation in cell lines.
• Mass Spectrometry Characterization: Used to confirm molecular weight and purity of the recombinant protein.
• Immunofluorescence and Immunohistochemistry: Applied to study CXCL16 localization and expression in tissues, such as kidney biopsies and brain tissue, often in the context of disease models.
• In Vivo Functional Studies: Recombinant human CXCL16 has been used in animal models to investigate its role in immune cell recruitment, tumor immunity, and disease progression, including cancer and nephritis models.
• Western Blotting and Mass Cytometry (CyTOF): Used for protein detection and quantification in research settings.

Published research examples:

• Cancer Immunology: Recombinant human CXCL16 has been used to recruit T cells and enhance antitumor immunity in murine models of lymphoma, colorectal, and breast cancer, demonstrating therapeutic efficacy and immune cell activation.
• Kidney Disease: Applied in studies of podocyte function and glomerular disease, where it was shown to mediate chemotaxis and oxidized LDL uptake in human podocytes.
• Atherosclerosis and Inflammation: Used in functional studies to assess its role as a scavenger receptor and in immune cell trafficking in vascular and inflammatory diseases.

These applications are supported by both commercial validation and peer-reviewed research, confirming the utility of recombinant human CXCL16 in a wide range of immunological, biochemical, and disease model studies.

To reconstitute and prepare Recombinant Human CXCL16 protein for cell culture experiments, follow these general guidelines based on manufacturer protocols and best practices:

Reconstitution

1. Centrifuge the vial briefly before opening to ensure all lyophilized powder is at the bottom.

2. Reconstitute with sterile PBS or water as specified by the product datasheet. For example:

   • R&D Systems (976-CX): Reconstitute at 100 µg/mL in sterile PBS.
   • Bio-Techne (976-CX): Reconstitute at 25 µg/mL in PBS with BSA (if BSA is included, it helps stabilize the protein).
   • Leinco (C1335): Reconstitute with sterile PBS or appropriate buffer as indicated.
   • Thermo Fisher (300-55-25UG): Reconstitute with sterile water or buffer per datasheet.

   Always check the specific product datasheet for exact instructions, as some proteins may require a carrier protein (like BSA) or specific buffers.

3. Gently swirl or pipette up and down to dissolve the protein. Avoid vigorous vortexing to prevent denaturation.

Preparation for Cell Culture

1. Aliquot the reconstituted protein into small volumes to avoid repeated freeze-thaw cycles.
2. Store aliquots at -20°C to -80°C for long-term storage. For short-term use (within a week), store at 2–8°C.
3. Thaw aliquots on ice before use and keep on ice during experiments.
4. Dilute the protein in cell culture medium (e.g., RPMI, DMEM) to the desired working concentration. Typical working concentrations range from 10–100 ng/mL, but this depends on your experimental design and cell type.
5. Filter the diluted protein through a 0.22 µm filter if sterility is critical for your cell culture.

Additional Tips

• Avoid repeated freeze-thaw cycles to maintain protein activity.
• Use carrier protein (e.g., BSA) if recommended, especially for low-concentration dilutions, to prevent adsorption to plastic surfaces.
• Test a range of concentrations to determine the optimal dose for your cell culture experiment.

Example Protocol

1. Centrifuge the lyophilized CXCL16 vial.
2. Reconstitute with sterile PBS to 100 µg/mL.
3. Aliquot and store at -80°C.
4. Thaw an aliquot on ice, dilute in cell culture medium to 50 ng/mL.
5. Add to cells and incubate as required.

Always refer to the specific product datasheet for detailed instructions and recommended concentrations.