Components of the Immune System
. The ability of the immune system to mount a response to disease is dependent on many complex interactions between the components of the immune system and the antigens on the invading pathogens, or disease-causing agents. A. Macrophages White blood cells are the mainstay of the immune system. Some white blood cells, known as macrophages, play a function in innate immunity by surrounding, ingesting, and destroying invading bacteria and other foreign organisms in a process called phagocytosis (literally, “cell eating”), which is part of the inflammatory reaction. Macrophages also play an important role in adaptive immunity in that they attach to invading antigens and deliver them to be destroyed by other components of the adaptive immune system. B. Lymphocytes Lymphocytes are specialized white blood cells whose function is to identify and destroy invading antigens. All lymphocytes begin as “stem cells” in the bone marrow, the soft tissue that fills most bone cavities, but they mature in