Monocyte Absolute

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Monocyte is a type of white blood cell, part of the human body's immune system. Monocytes have several roles in the immune system and this includes: (1) replenish resident macrophages and dendritic cells under normal states, and (2) in response to inflammation signals, monocytes can move quickly (approx. 8-12 hours) to sites of infection in the tissues and divide/differentiate into macrophages and dendritic cells to elicit an immune response. Half of them are stored in the spleen. Monocytes are usually identified in stained smears by their large bilobate nucleus.

Depending on a patient's level of health, monocytes make up between one and three percent of the total white blood cells in the body. They can be counted as part of a blood test, and changes in their levels can indicate changes in a patient's health. As a general rule, a low monocyte count is a good sign, and a high count indicates that a problem is present.

Monocytes help other white blood cells remove dead or damaged tissues, destroy cancer cells, and regulate immunity against foreign substances. Monocytes are produced in the bone marrow and then enter the bloodstream, where they account for about 1 to 10% of the circulating leukocytes (200 to 600 monocytes per microliter of blood). After a few hours in the bloodstream, they migrate to tissues (such as spleen, liver, lung, and bone marrow tissue), where they mature into macrophages, the main scavenger cells of the immune system. Genetic abnormalities that affect the function of monocytes and macrophages and cause buildup of debris within the cells result in the lipid storage disorders (such as Gaucher's disorder and Niemann-Pick disorder).

These cells are made in the bone marrow, and they spread through the body in one to three days. They can develop into either dendritic cells or macrophages. Dendritic cells belong to a group of cells known as antigen presenting cells, because they acquire antigens and show them to T cells so that the T cells learn to recognize dangerous antigens. Dendritic cells typically present antigens to T cells before they are fully developed, so that the T cell can respond appropriately after it has been shown an antigen.
Macrophages are cells which eat other cells. Classically, they attack any foreign material, such as a bacteria or virus, consuming it so that it cannot hurt the body and preserving an antigen so that the body will be able to recognize the foreign material in the future. Macrophages can also eat cells in the body which have been infected by a pathogen, to curb the spread of the pathogen and keep the body healthy.
Levels of monocytes in the blood tend to rise when someone has an infection, because more of these cells are needed to fight it. Monocytes can also increase in response to stress and other factors. A high monocyte count may be referred to as monocytosis, and it is typically addressed by determining why the count is so high, and addressing the problem. For example, if monocytes are elevated because of an inflammation caused by a viral infection, the patient would be given medication to kill the virus and bring down the inflammation.

Any infection or acute stress increases your number of white blood cells. High white blood cell counts may be due to inflammation, an immune response, or blood disorders such as leukemia.
It is important to realize that an abnormal increase in one type of white blood cell can cause a decrease in the percentage of other types of white blood cells.

Monocytosis is the state of excess monocytes in the peripheral blood. It may be indicative of various disorder states. Examples of processes that can increase a monocyte count include:
·Chronic inflammatory disorder  
·Parasitic infection  
·Viral infection (for example, infectious mononucleosis, mumps, measles)  
·stress response  
·immune-mediated disorder  
·pyogranulomatous disorder  
·red cell regeneration  
An increased number of monocytes in the blood (monocytosis) occurs in response to chronic infections, in autoimmune diseases, in blood diseases, and in cancers. A proliferation of macrophages in tissues can occur in response to infections, sarcoidosis, and Langerhans' cell histiocytosis. A high count of CD14+CD16+ monocytes is found in severe infection (sepsis) and a very low count of these cells is found after therapy with immuno-suppressive glucocorticoids.

A low number of monocytes in the blood (monocytopenia - a form of leukopenia associated with a deficiency of monocytes) can occur in response to the release of toxins into the blood by certain types of bacteria (endotoxemia), as well as in people receiving chemotherapy or corticosteroids.

Difference between percentage of monocytes and absolute monocyte count (AMC)
Absolute counts are extremely important. If monocyte or other counts are reported as percentages of the total white blood count (wbc), the absolute values can be calculated as follows: Total wbc x % cell type reported / 100. This formula can be used for calculating the absolute monocyte count, absolute neutrophil count, etc.
By way of example, if the total white count reported is 25,000 and the percentage of monocytes reported is 80%, the calculation is as follows: 25,000 x 80 / 100. The result is an absolute monocyte count of 20,000.

All information on this page is intended for your general knowledge only and does not provide medical advice, diagnosis or treatment.