IL-12 and viral infections

Interleukin-12 activates natural killer cells and promotes the differentiation of Th1 CD4+ cells; it is a critical factor in viral immunity. IL-12 is secreted by antigen presenting cells including dendritic cells, macrophages and astrocytes, both in tissues and in secondary lymphoid organs. Experimental studies have shown that administration of the cytokine rapidly activates both innate and specific immune responses; this results in enhanced host cellular responses and generally, promotes clearance of virus and host recovery from infection. The observations of many laboratories, studying viral immunity to both RNA and DNA based pathogens, are summarized.