Monocytes are a type of white blood cells contained in the blood and play an important role in the body's immune response. These are the largest leukocyte types and are mononuclear, which means they enter the agranulocyte group. In a healthy adult monocytes the range of monocytes ranges from 3 to 7% of the total white blood cells contained in the blood and their normal count is usually between 100 and 800 per microliter of blood in an adult person and between 400 and 3100 per microliter of blood for a newborn.
Changes in normal monocyte levels may indicate conditions in the patient's health. As a general rule, when monocyte counts are kept low it is a good indicator, and when levels are high it indicates that a problem is present.
Monocytes circulate in the blood for 1 to 3 days, after which they are stored in tissues around the whole body to mature and become dendritic cells or macrophages, but approximately 50% of them are stored in the spleen. They occur in the bone marrow from the monoblasts.
Low levels of monocytes:
When the levels of monocytes are low in the blood count is called monocytopenia, this is a form of leucopenia. When there is a decrease in monocytes in the blood the body is more prone to infections and diseases. The decline in these white blood cells may be a cause of a variety of reasons for physical illness, vitamin deficiency, or treatment with some drugs, but medical conditions that hamper normal bone marrow performance are the main factors lead to a decrease in monocytes. Viruses such as HIV, autoimmune diseases such as rheumatoid arthritis or lupus can lead to a low count of monocytes in the body, as well as the use of some drugs such as corticosteroids, oral interferons and treatment such as chemotherapy. The nutritional deficiency where a low intake of folate or vitamin B12, can cause a low of these white cells.
High levels of monocytes:
Monocyte levels above the normal level in a healthy person tend to appear in blood tests when one is in the presence of some foreign agent to the organism that causes infections, because the body produces more of these cells to fight with the pathogen present. Stress may be another factor that triggers a high production of monocytes, when this clinical condition is called monocytosis. Inflammatory conditions, immune disorders such as rheumatoid arthritis or lupus, as well as tuberculosis or syphilis infections, are the most common causes for a patient to have a high monocyte count. Some disorders in the blood can lead a person to present monocytosis. Leukemia or Hodgkin's disease are cancers that cause a high production of monocytes.