There is a growing appreciation of the importance of innate immune responses to infections. These responses are produced by non-immune cells and cells of the innate immune system, including monocyte/macrophage populations, granulo-cytes, dendritic cells (DCs), and natural killer (NK) cells. Cytokines can be a part of the innate responses of non-immune cells to infections. The cell constituents of the innate immune system can respond with activation of other anti-microbial effector functions as well as cytokine production. Innate responses act both to mediate defense during periods of development of, and to direct the quality and nature of, downstream adaptive immune responses. The type 1 interferons, interferons alpha and beta (IFN-α/β), induced at early times during viral infections, are examples of innate cytokine responses to infections. Another is interleukin 12 (IL-12) induction during challenges with a variety of agents. Host pattern recognition molecules identifying the distinguishing chemical characteristics of infectious organisms induce initial innate responses (Biron 1999). The best studied of these are cell surface receptors binding and stimulating responses to bacterial products, and associated with the induction of an innate pro-inflammatory cytokine cascade including IL-12 and accompanied by IL-12-induced NK cell type 2 interferon, interferon gamma (IFN-γ), production.