Sterile-filtered solution comprised of PBS, pH 7.2, with FBS as a carrier and stabilizer.
Endotoxin Level:
The endotoxin level is less than 0.1 ng per µg cytokine protein (< 1EU/µg).
Concentration:
0.01 mg/ml
Storage & Handling:
After thawing, quick spin vial. Make working aliquots for storage at ≤ -70°C to minimize repeated freeze/thaw cycles. Any further dilution of the cytokine should be done using a buffered diluent containing a protein carrier (e.g., 1% BSA or 10% FBS). For greatest stability, the cytokine protein is best kept at relatively high concentrations and in the presence of a protein carrier.
Each lot of this protein is quality control tested by ELISA assay. For use as a calibrator in an IL-12 p40 ELISA, a standard curve from 4000 pg/ml to 30 pg/ml is suggested. It is recommended that the reagent be titrated for optimal performance for each application.
Application Notes:
ELISA: This IL-12 protein is useful as a standard for a human IL-12 sandwich ELISA, using unlabelled C8.3 antibody (catalog #501702) for capture and biotinylated C8.6 antibody (catalog #508802) for detection. This assay is specific for p40 monomer and is not reactive with p70 heterodimer or p40 homodimer. Ligand Blocking: This IL-12 protein is useful as a ligand-blocking specificity control for immunohistochemical or immunofluorescent staining. Bioassay: Monomeric human IL-12 p40 has little or no IL-12 antagonistic activity.
Description:
Bioactive IL-12 is a potent regulator of cell-mediated immune responses and key mediator of Th1 cell development. Bioactive IL-12 is secreted by activated B lymphocytes, dendritic cells and macrophages as a 70 kD heterodimeric glycoprotein comprised of disulfide-bonded 35 kD and 40 kD subunits. The p40 protein is also a subunit of IL-23 (p60). The disulfide-linked p40 homodimer can bind to IL-12 receptors and antagonize the activities of bioactive IL-12. IL-12 p40 monomer is secreted in vast excess of IL-12 p70 heterodimer; IL-12 p40 monomer has no activity and is antagonistic to IL-12 p70 with only 1/10th the activity of p40 homodimer. Recombinant human IL-12 p40 monomer contains 306 amino acids.
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