Interleukin 4 (IL-4) is an immunomodulatory cytokine that functions to induce naïve 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-4Ra receptor to activate STAT6 signaling.
Bioactivity Assay:TF-1 cell proliferation; ED50 =25 ng/mL; Bioactivity =4.0 x 10^4 units/mg