Described herein are compositions for increasing IL-12 production comprising IgG or a fragment thereof or a variant thereof and uses of said compositions for treating cancer and infectious diseases. Also described herein are compositions for decreasing IL-12 production comprising an agent that inhibits signaling mediated by interaction between FcRn and IgG and uses of said compositions for treating autoimmune diseases. Further described herein are methods for assessing efficacy of treatment by monitoring levels of various cytokines in the subject.
