Submitted to: Encyclopedia of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 18, 2003
Publication Date: November 10, 2004
Citation: Bannerman, D.D., Paape, M.J., Lunney, J.K. 2004. Immunity: innate IN Encyclopedia of Animal Science. W.G. Pond and A.W. Blel, editors. Marcell Dekker, Inc. New York pp. 552-554.
Interpretive Summary: Innate immunity represents an ancient and highly conserved means by which the host can defend itself against pathogens that have penetrated the physical barriers of the skin and other tissues. The ability of the innate immune system to respond immediately to invading pathogens, as well as, to respond to a broad variety of infectious agents with a limited repertoire of receptors and molecules, delineates this system from that of adaptive immunity. Thus, the innate immune system serves as the initial mode by which the host defends itself from potential injurious pathogens.
The ability of pathogens to establish a successful infection is mediated by both intrinsic properties of the pathogen itself and the ability of the host to respond to the invading organism. The immune system is responsible for responding to and protecting against infectious agents and is comprised of innate and adaptive components. The innate immune system represents the first line of defense in the host response to infection. Unlike the adaptive (acquired) immune response, which requires several days to generate effector lymphocytes in the numbers necessary to mount an effective immune response, the innate immune system is poised to immediately recognize and respond to the earliest stages of infection. Whereas the adaptive immune system of an organism acquires over time the ability to readily respond to highly specific antigens found on previously encountered pathogens, the innate immune system is able to respond to pathogens that have not been previously or repeatedly encountered. Thus, differences in the time needed to respond to a pathogen, the requirement for host memory, and the effector cells and molecules involved in the response, all distinguish innate immunity from that of adaptive immunity.