The innate immune system

The innate immune system ; is an important subsystem of the overall immune response system that comprises the cells and mechanisms that defend the host from infection by other organisms. The cells of the innate system recognize and respond to pathogens in a generic way, but, unlike the adaptive immune system, the system does not confer long-lasting or protective immunity to the host. Innate immune systems provide immediate defense against infection, and are found in all classes of plant and animal life. The major functions of the vertebrate innate immune system include: • Recruiting immune cells to sites of infection, through the production of chemical factors, including specialized chemical mediators, called cytokines • Activation of the complement cascade to identify bacteria, activate cells, and promote clearance of antibody complexes or dead cells • Identification and removal of foreign substances present in organs, tissues, the blood and lymph, by specialized white blood cells • Activation of the adaptive immune system through a process known as antigen presentation Acting as a physical and chemical barrier to infectious agents.