Introduction
Interleukin-16 (IL-16) is a multifunctional cytokine that plays roles in chemotaxis, T cell activation modulation, and HIV replication inhibition. It exerts its effects by binding to the CD4 receptor. IL-16 undergoes proteolytic processing, resulting in two functional proteins. The C-terminal peptide, generated through this processing, is responsible for the cytokine's biological activities, while the N-terminal fragment might be involved in cell cycle regulation. Caspase 3 has been implicated in the proteolytic cleavage of IL-16. This gene exhibits two transcript variants that encode distinct protein isoforms. IL-16 exhibits chemoattractant properties towards CD4+ lymphocytes, monocytes, and eosinophils, inducing their migration. Furthermore, it stimulates the expression of the interleukin-2 receptor, the ligand for CD4, on T lymphocytes.
Description
Recombinant Human Interleukin-16, expressed in E. coli, is a single, non-glycosylated polypeptide chain consisting of 130 amino acids with a molecular weight of 13.5 kDa. The purification of IL-16 is achieved using proprietary chromatographic methods.
Physical Appearance
Sterile Filtered White lyophilized powder.
Formulation
The lyophilization of IL-16 was carried out at a concentration of 1 mg/ml in 10mM NaP buffer with a pH of 7.5.
Solubility
For reconstitution of the lyophilized Interleukin-16, sterile 18MΩ-cm H2O is recommended at a concentration of not less than 100 µg/ml. This reconstituted solution can be further diluted in other aqueous solutions as needed.
Stability
Lyophilized Interleukin-16, while stable at room temperature for a duration of 3 weeks, is best stored in a desiccated state at a temperature below -18°C. After reconstitution, it is advisable to store IL16 at 4°C for a period of 2-7 days. For long-term storage, freezing at -18°C is recommended. To enhance stability during long-term storage, the addition of a carrier protein, such as HSA or BSA, at a concentration of 0.1% is suggested. It is important to avoid repeated freeze-thaw cycles.
Purity
The purity of the protein is greater than 90.0% as determined by the following methods: (a) Analysis by RP-HPLC. (b) Analysis by SDS-PAGE.
Biological Activity
The ED50, determined by the cytokine's ability to induce chemotaxis in human CD4+ T lymphocytes, falls within the range of 10-100 ng/ml. This corresponds to a specific activity of 10,000-100,000 units/mg.
Synonyms
IL16, Interleukin-16, LCF, Lymphocyte Chemoattractant Factor, prIL-16, IL-16, FLJ16806, FLJ42735, FLJ44234, HsT19289.
Amino Acid Sequence
The sequence of the first five N-terminal amino acids was determined and was found to be Met-Pro-Asp-Leu-Asn.
