Monocytes (Absolute)

Optimal Result: 0.1 - 0.9 x10E3/uL, 0.10 - 0.90 abs, 0.10 - 0.90 x10^9/L, or 100.00 - 900.00 cells/uL.

What are Monocytes?

Monocytes are a type of white blood cell ( leukocytes ) in your immune system.

Monocytes reside in your blood and tissues to find and destroy germs (viruses, bacteria, fungi and protozoa) and eliminate infected cells. Monocytes call on other white blood cells to help treat injury and prevent infection.

Monocytes turn into macrophage or dendritic cells when an invading germ or bacteria enters your body. The cells either kill the invader or alert other blood cells to help destroy it and prevent infection.

Monocytes are the largest of the white blood cells and are about twice the size of red blood cells. These powerful defenders aren’t plentiful in the bloodstream but they’re vital in protecting the body against infection.

What do Monocytes do?

Monocytes, along with other kinds of white blood cells, help the body fight disease and infection .

Monocytes move throughout the bloodstream to the tissues in the body. They rest until needed and then transform into macrophages or dendritic cells. These are both different kinds of white blood cells.

• When they become dendriticcells, they play a part in launching the inflammatory and anti-inflammatory processes that are part of your body’s immune response to infection. Dendritic cells use receptors to show the antigens to other immune system cells. They can cause monocytes to travel through the body to the affected tissues.
• As macrophagecells, they can destroy microorganisms and foreign material, get rid of dead cells, and boost the body’s immune response. Macrophages kill microorganisms and fight cancer cells. They also work with other white blood cells to remove dead cells and support the body’s immune system against foreign substances and infections. One way macrophages do this is by signaling to other cell types that there is an infection. Together, several types of white blood cells then work to fight off the infection. Exposure to pathogens (disease-causing substances) can start the process of a monocyte becoming a macrophage. Once fully activated, a macrophage can release toxic chemicals that kill harmful bacteria or infected cells. Macrophages can digest germs if they have been coated by antibodies by other white blood cells.

What is ‘Monocytes (absolute)’?

A blood cell count measures the number of white blood cells in your blood. When you get a comprehensive blood test that includes a complete blood count, you may notice a measurement for monocytes. It’s often listed as “monocytes (absolute)” because it’s presented as an absolute number.

You may also see monocytes noted as a percentage of your white blood cell count, rather than as an absolute number.

Low levels can result from certain medical treatments or bone marrow problems while high levels can indicate the presence of chronic infections or an autoimmune disease.

Where are monocytes formed?

Monocytes form in bone marrow from undifferentiated blood cells, which are blood stem cells that have not yet changed to become a specialized cell type. After forming, monocytes then enter the bloodstream. They travel throughout the body before entering the tissue of the different organs, such as the spleen, liver, and lungs, as well as bone marrow tissue, to look for pathogens.

What do monocytes look like?

Monocytes are the largest type of white blood cell and are nearly twice the size of a red blood cell. Under a microscope, monocytes are easy to identify based on their size. Monocyte cells have a two-bodied nucleus (bilobed nuclei) center that floats in a contained fluid called cytoplasm.

What is a normal range for my monocyte count?

Conditions vary based on the number of monocytes in your blood. Your monocyte count can be too high or too low as a result of your body fighting an infection or disease. A normal monocyte count is between 2% and 8% of your white blood cell count. This equals about 200 to 800 monocytes per microliter of blood in healthy adults. If your monocyte count is outside those ranges, you are at risk of acquiring a monocyte-related condition.

References:

Espinoza VE, Emmady PD. Histology, Monocytes. 2022 Apr 28. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 32491550.

The complete blood count: A guide for patients with cancer. (2018). uihc.org/health-topics/complete-blood-count-guide-patients-cancer

Espinoza V, et al. (2021). Histology, monocytes. ncbi.nlm.nih.gov/books/NBK557618/

Low white blood cell counts (neutropenia). (2000). cancer.org/treatment/treatments-and-side-effects/physical-side-effects/low-blood-counts/neutropenia.html

Macrophage. (n.d.). cancer.gov/publications/dictionaries/cancer-terms/def/macrophage

Monocyte. (n.d.). cancer.gov/publications/dictionaries/cancer-terms/def/monocyte

Understanding blood counts. (n.d.). lls.org/managing-your-cancer/lab-and-imaging-tests/understanding-blood-counts