Innate immune recognition: mechanisms and pathways

The innate immune system is an evolutionarily ancient form of host defense found in most multicellular organisms. Inducible responses of the innate im mune system are triggered upon pathogen recognition by a set of pattern rec ognition receptors. These receptors recognize conserved molecular patterns shared by large groups of microorganisms. Recognition of these patterns all ows the innate immune system not only to detect the presence of an infectio us microbe, but also to determine the type of the infecting pathogen. Patte rn recognition receptors activate conserved host defense signaling pathways that control the expression of a variety of immune response genes.