IL-12 is a potent regulator of cell-mediated immune responses and it induces IFN-γproduction by NK and T cells. It is produced by activated monocytes/macrophage cells, B lymphocytes and connective tissue-type mast cells. Among its biological activities, IL-12 promotes the growth and activity of activated NK, CD4+ and CD8+ cells, and induces the development of IFN-γ-producing Th1 cells. Recombinant Murine IL-12 p80 is an 80.0 kDa, disulfide linked homodimer of two p40 chains of IL-12 that consists of 626 amino acid residues and less than 5% of the IL-12 p40 monomer