Functions Of White Blood Cells In The Immune System – Macrophages are a type of white Blood cell that play an important role in the human immune system and perform various functions including digesting and digesting microorganisms; clearing out dust and dead cells; and stimulating other cells involved in immune function. Macrophages provide innate immunity, which is usually the first line of defense against foreign antigens. Adaptive immunity, on the other hand, is a subtype of the immune system that involves immune cells and specific antibodies. In addition to having an immune role, macrophages also secrete anti-inflammatory cytokines (ie, small signaling proteins) and help mediate the reparative process.
Macrophages form from monocytes, which themselves come from the bone marrow. Monocytes circulate through the blood for one to three days before migrating to tissues, where they become macrophages or dendritic cells (ie, a type of antigen presenting cell that plays a role in linking innate and adaptive immunity). Macrophages can be found in many organs in the body, including the liver, brain, bones, and lungs, as well as in the blood, especially at sites of infection.
Functions Of White Blood Cells In The Immune System
Macrophages can be largely classified into two main types: M1 and M2 macrophages. The M1 type, classically called activated macrophages, is activated by invading pathogens and plays a major role in the immune response to foreign pathogens such as bacteria. Type M2, referred to as alternative-activated macrophages, plays a role in wound healing and tissue repair, and has an anti-inflammatory role.
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In general, macrophages play a role in destroying infectious organisms that enter the body, clearing cellular debris, and healing wounds. It also plays an important role in the formation of granulomas, which are aggregations of macrophages that function in the walls of an infection. The specific function of M1 macrophages is to detect, engulf and destroy bacteria. It can do this through phagocytosis, which is a process that forms a bridge between cellular receptors on macrophages and surface antigens on bacteria. Once the bridge is formed, the macrophage membrane protrudes out and surrounds the bacteria. Once inside the macrophage, the bacteria are trapped in phagosomes, or vesicles, which then fuse with lysosomes. Lysosomes contain enzymes and peroxides that can digest pathogens. M1 macrophages promote inflammation; destruction of extracellular matrix (ECM); cell apoptosis attacks by releasing various cytokines and nitric oxide to help cellular destruction; and antigen presentation, making it antigen-presenting cells (APCs). After macrophages process and digest the antigen, major histocompatibility complex (MHC) molecules deliver the antigen to the surface of the macrophage to allow T cell receptors to bind. This triggers the body’s adaptive immune response to recognize foreign antigens and Mount the next mechanism to kill cells.
M2 macrophages on the other hand are required for connective tissue regeneration during wound healing. They produce vascular endothelial growth factor (VEGF) and transforming growth factor (TGF)-β1 which allow for vascular stability and wound repair. M2 macrophages also function to phagocytize bacteria and damaged tissue around the wound. They can then debride the damaged tissue by releasing digestive enzymes such as proteases, which are enzymes that break down proteins. Next, they release growth factors, stimulate cells to re-epithelialize the wound, create granulation tissue, and lay down a new extracellular matrix.
Macrophages play an additional role in specific organ systems. For example, when air is inhaled into the lungs to exchange oxygen, toxic substances (such as bacteria, viruses, and fungi) can enter the lungs, specifically, the alveoli (ie, the air sacs of the lungs). Lung macrophages can process bacteria and other toxic substances in the alveoli to prevent diseases such as tuberculosis through granuloma formation. In the liver, macrophages are given the special name of Kupffer cells. Kupffer cells scavenge the liver for potential pathogens that may have entered the bloodstream from the gastrointestinal tract. It also plays a role in maintaining iron levels and has a function in bilirubin metabolism. When the liver is injured, Kupffer cells release anti-inflammatory cytokines (eg Interleukin [IL]-10, IL-4, and IL-13). Brain macrophages are called microglia. Microglia have a neuroprotective effect and release several anti-inflammatory cytokines and nerve injury factors. When neurons are damaged, microglia are recruited to the site, and can phagocytose dead cells and foreign material to prevent further tissue damage.
Overall, macrophages are good and play a critical role in the human body. They protect our bodies from bacterial and viral infections by releasing antimicrobial mediators and pro-inflammatory cytokines, while also promoting repair through anti-inflammatory responses. It also allows protection from neuronal damage in the brain, and regulates iron and bilirubin levels in the liver.
Mapping The Types And Traits Of Immune Cells
However, there are some pathological effects of macrophages. For example, one type of M2 macrophage, the tumor-associated macrophage (TAM), promotes tumor growth through suppression of the immune system. Therapies are currently being developed to target TAMs. In addition, M1 and M2 macrophage populations play a role in promoting atherosclerosis, which is an arterial disease characterized by fat deposition in the vessel wall. M1 macrophages cause vessel inflammation, while M2 macrophages remove cholesterol from blood vessels, which is then oxidized and converted into atheromatous plaques. Hypertension and cardiovascular disease can be a consequence of this process.
Macrophages are a type of white blood cell that play an integral part in the immune system with the role of phagocytosis of foreign antigens, such as bacteria. They can present these antigens to other immune cells, such as T-cells, for further destruction. Macrophages also play a role in wound healing and tissue repair. They attract anti-inflammatory cytokines, which mediate vascular growth and have microcidal properties, to the wound site. Macrophages have very positive effects and maintain tissue homeostasis in humans, but they can also contribute to disease. This may be the case when tumor-associated macrophages evade suppression by the immune system and promote tumor growth, or when atherosclerosis is promoted in arteries by the action of macrophages.
Gordon, S., Martinez, F. O. (2010). Alternative activation of macrophages: mechanisms and functions. Immunity, 32(5): 593-604. DOI: 10.1016/j.immuni.2010.05.007
Kreutzberg, G. W. (1996). Microglia: Sensors for pathological events in the CNS. Trends in Neurosciences, 19(8): 312-318. DOI: 10.1016/0166-2236(96)10049-7
Question Video: Identifying The Leukocytes Of The Human Immune System
Lin, Y., Xu, J., & Lan, H. (2019). Tumor-associated macrophages in tumor metastasis: biological roles and clinical therapeutic applications. Journal of Hematology & Oncology, 12 (1): 76. DOI: 10.1186/s13045-019-0760-3
Mills, C. D., Kincaid, K., Alt, J. M., Heilman, M. J., & Hill, A. M. (2000). M-1/M-2 macrophages and the th1/th2 paradigm. The Journal of Immunology, 164 (12): 6166-6173. DOI: 10.4049/jimmunol.164.12.6166
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Blood Function And Composition
When an infection or inflammatory condition occurs, the body releases white blood cells to help fight the infection.
Health professionals have identified three main categories of white blood cells: granulocytes, lymphocytes, and monocytes. The following sections discuss this in more detail.
Granulocytes are white blood cells that contain small granules that contain protein. There are three types of granulocyte cells:
Monocytes are white blood cells that make up about 2-8% of the total number of white blood cells in the body. This is present when the body fights chronic infections.
Types Of Macrophages
According to an article in American Family Physician, the normal range (per cubic millimeter) of white blood cells by age is:
If a person’s body produces more white blood cells than it should, doctors call it leukocytosis.
If a person’s body produces less white blood cells than it should, doctors call it leukopenia.
Doctors can continue to monitor white blood cells to determine whether the body has an increased immune response to infection.
Immune System And Disorders
During the physical examination, the doctor may perform a white blood cell (WBC) count using a blood test. They may order WBCs to test for, or rule out, other conditions that may affect white blood cells.
Although a blood sample is the most common approach to testing white blood cells, doctors may also test other body fluids, such as cerebrospinal fluid, for the presence of white blood cells.
This is a condition that can affect how many white blood cells are in the body.
This is an autoimmune condition in which the body’s immune system destroys healthy cells, including red and white blood cells.
White Blood Cell Count As A Prognostic Indicator Of Covid 19
The number of white blood cells called CD4 T cells. When a person’s T cell count drops below
Leukemia is a type of cancer that affects the blood and bone marrow. Leukemia occurs when white blood cells produce too quickly and cannot fight infection.
Whether or not a person needs to change their white blood cell count will depend on the diagnosis.
If they have a medical condition that affects the white count
Biology, Animal Structure And Function, The Immune System, Innate Immune Response
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