Sigma-Aldrich Protein Delivery System Human Il-4 PO&

Protein delivery system, IL-4, PODS contains the polyhedrin protein co-crystalized with Human IL-4. Interleukin-4 (IL-4) is an immunomodulatory cytokine that functions to induce naive helper T cells to differentiate into type 2 T helper (Th2) cells. Th2 cells subsequently produce more IL-4 in a positive feedback loop. IL-4 also promotes immunoglobulin IgG to IgE isotype switching on B cells. IL-4 binds the IL-4Rα receptor to activate STAT6 signaling.

PODS are composed of a bioactive cargo protein within a polyhedrin crystal lattice, with polyhedrin as the main protein. The 25 µg SKU size indicates the amount of bioactive cargo, typically 0.5% to 5% of the total protein. For instance, a 25 µg SKU at a 2% cargo loading contains 1.25 mg of total protein. PODS enable sustained release of cargo proteins when proteases degrade the polyhedrin scaffold. Growth factors are not bioavailable until released, and their concentration in media depends on the amount added and the release rate. In 10% serum, peak levels are usually reached within 24-48 hours, with about 20% of the cargo becoming soluble.

PODS often require lower concentrations than conventional growth factors, as they maintain effective levels. Pre-incubating with serum or proteases enhances availability, while conventional factors can be added for immediate effects. Optimal amounts should be determined empirically.

PODS is a registered trademark of Cell Guidance Systems Ltd