The immune system

Immune system: Interacting white blood cells that defend the body through self/nonself recognition, specificity, and memory. Disease: A disorder of structure or function in a human, animal, or plant, esp. one that produces specific signs or symptoms or that affects a specific location and is not simply a direct result of physical injury. T cells: antigen receptors ignore the body's own cells yet collectively recognize at least a billion specific threats. B cells: formed in a primary response are set aside as memory cells for future battles with the same antigen. Immunity: The body's overall ability to resist and combat any substance foreign to itself. infection: Invasion and manipulation of a pathogen in a host. Disease follows if defenses are not mobilized fast enough; the pathogen's activities interfere with normal body functions. Inflammation: Process in which, in response to tissue damage or irritation, phagocytes and plasma proteins, including complement proteins, leave the bloodstream, then defend and help repair the tissue. Occurs during both nonspecific and specific (immune) defense responses. Innate immunity: The body's inborn, reset immune responses, which act quickly when tissue is damaged or microbes have invaded. Interleukin: One of a variety of chemical communication signals - secreted by macrophages and helper T cells- that drive immune responses. Antigen Presenting: A type of cell. A macrophage or other cell that display antigen-MHC complexes at its surface and so promotes an immune response by lymphocytes. Adaptive immunity: Immune responses that the body develops in response to antigens of specific pathogens, toxins, or abnormal body cells.