CD4 and neoplasm: The main elements of IL-12 actions are as follows (Fig. 1): increasing production of IFN-γ, which is the most potent mediator of IL-12 actions, from NK and T cells [26]; stimulation of growth and cytotoxicity of activated NK cells, CD8+ and CD4+ T cells [27], shifting differentiation of CD4+ Th0 cells toward the Th1 phenotype [28]; enhancement of antibody-dependent cellular cytotoxicity (ADCC) against tumor cells [29, 30]; and the induction of IgG and suppression of IgE production from B cells [31].