What Are Macrophages?
Macrophages are a type of white blood cell which eat foreign material in the body. These cells are involved in the primary or innate immune response to a number of immune invaders, and they also make up an important part of the body’s acquired immune system. At any given time, macrophages are at work in many corners of the body, quietly cleaning up foreign debris, bacteria, and viruses before they have a chance to cause a problem. Like other blood cells, macrophages start out in the bone marrow. The life cycle of a macrophage actually starts with a type of cell called a monocyte, which has the capability to mature into a macrophage when it is stimulated to do so. Some monocytes drift to specific areas of the body, such as the liver, where they mature into specialized macrophages which remain in place, while others turn into free-floating macrophages. In a sense, macrophages are like security guards for the immune system. Some of them remain stationed at their regular “desks” near areas
• Macrophages are white blood cells that identify intruders through the molecules that cover the intruders’ surfaces (antigens)1 • They are part of the “nonspecific immune system,” and are the first to react to foreign invaders3 • Their response time does not change no matter how many times a microbe attempts to infect the body • These white blood cells eat the microbes and carry the antigens back to “home base” in the lymph nodes1 • Lymph nodes are bean-sized organs scattered throughout your body and act as gathering spots for the white blood cells1 • Here, the macrophages “sound the alarm” to other white cells (helper T cells) by showing them the antigens from the microbe. That way, helper T cells can recognize them.
Macrophages are large white immune cells representing the first line of defense in the initiation and maintenance of the immune response. Like all blood cells, Macrophages originate in the bone marrow from a pluripotent stem cell. As it matures and enters the blood stream it becomes a monocyte. Monocytes enlarge in the blood before entering the tissue as mature Macrophages. From an evolutionary point of view, the Macrophage is the oldest and most consistently preserved immunologically competent cell known. Not only humans and higher animals, but primitive invertebrates such as Hydra which have no other immunological effector cells, have Macrophages. Macrophages with various names exist in all tissues, organs, blood and lymph and are classified as phagocytes to devour, breakdown and dispose of foreign particles in the cell-mediated immune response. Macrophages also participate in the innate or non-specific immune first response that attacks and attempts to kill any substance that does n
