Mouse IL-12 p70 Carrier-Free Recombinant Protein, eBioscience?. Interleukin-12 (IL-12) is a heterodimeric 70 kDa cytokine composed of two covalently linked, glycosylated chains with molecular weights of 40kD (p40) and 35-kD (p35). IL-12 is mainly produced by monocytes, macrophages, and dendritic cells in response to bacterial products such as lipopolysaccharides (LPS), to intracellular pathogens or upon interaction with activated T cells. IL-12 was originally discovered because of its ability to induce interferon-gamma (IFN-g) production, cell proliferation, and cytotoxicity mediated by natural killer cells and T cells. Studies have established that IL-12 also plays a key role in the development of Th1 responses, leading to IFN-g and