Why are monocytes needed and how many should be normal?

What are monocytes

Monocytes Monocyte Disorders / МSD Manual are a type of white blood cells (leukocytes), with the help of which human immunity resists various infections and other diseases.

Like all white blood cells, monocytes are produced in the bone marrow and from there are sent to the bloodstream. But then something unusual happens to them, which determines the main function of these blood cells.

Why do you need monocytes

After wandering in the blood for several hours, young monocytes penetrate into various organs and tissues of the body. For example, in the spleen, liver, lungs, bone marrow tissue. Here these white blood cells mature by Karlin Karlmark, F. Tacke, and I. Dunay. Monocytes in health and disease - Minireview / European Journal of Microbiology and Immunology in macrophages.

Macrophages / British Society for Immunology are the main scavenger cells of the immune system. They hunt for pathogenic bacteria and other microorganisms, capture and devour foreign bodies (this process is called phagocytosis). They also destroy dead or damaged cells, for example, by a virus or cancer, cells of their own body. Macrophages also produce cytokines, proteins that increase the inflammatory response that the body uses to fight off viruses or bacteria.

However, the functions of macrophages are much broader and more diverse. They also depend on the organ where these cells operate. For example:

In the lungs. Macrophages live in the alveoli and are engaged in the destruction of the smallest debris that entered the organ with inhalation. In addition, these cells are involved in the formation of immunity to various respiratory viruses, fungi, bacteria.
In the central nervous system. Macrophages destroy dead or old neurons and control the immune system in the brain.
In the spleen. Eliminate old or defective red blood cells (red blood cells).

From the point of view of science, macrophages and their precursors monocytes are the most important element of innate immunity. That is, that "pre-installed" protective system with which we are born.

At the same time, they play a significant role in the creation of acquired immunity. For example, it is known that macrophages help T-lymphocytes to quickly recognize the already familiar pathogens of various infections and, as a result, accelerate the immune response Angel A. Justiz Vaillant, Sarah Sabir, Arif Jan. Physiology, Immune Response / Treasure Island (FL): StatPearls Publishing; 2021 Jan-. for infection.

How exactly all this works, scientists still have not figured out Karlin Karlmark, F. Tacke, and I. Dunay. Monocytes in health and disease - Minireview / European Journal of Microbiology and Immunology. But it is already clear that without monocytes, we would not be able to resist even the weakest infection. What is there - even dust that accidentally got into the lungs.

What is the norm of monocytes in the blood

The number of monocytes is determined by a general blood test.

In a healthy person, monocytes are Lyrad K. Riley, Jedda Rupert. Evaluation of Patients with Leukocytosis / American Family Physician 2–8% of total leukocyte count.

Translated into absolute numbers, we are talking about 200-600 Monocyte Disorders / МSD Manual monocytes per microliter of blood. Or about 0.2-0.6 × 10 ⁹per liter.

When the number of monocytes rises or falls, this indicates that something is happening to the person's immune system.

Why are monocytes elevated

A high level of monocytes is called monocytosis. This state may indicate Monocyte Disorders / MSD Manual to:

the presence in the body of some kind of chronic infection;
chronic inflammatory diseases - for example Alyce Anderson, Cynthia Cherfane, Benjamin Click, at al. Monocytosis Is a Biomarker of Severity in Inflammatory Bowel Disease: Analysis of a 6 ‑ Year Prospective Natural History Registry / Inflammatory bowel diseases, ulcerative colitis, Crohn's disease;
autoimmune disorders such as lupus or rheumatoid arthritis. With such failures, macrophages begin to mistakenly hunt for healthy cells in their own body. Since there are many healthy cells, the number of monocytes increases;
various blood diseases;
some types of cancer.

Why are monocytes low

If monocytes are less than normal, doctors talk about a condition called monocytopenia. Its cause is some factor due to which the number of leukocytes in general drops sharply. This can be Monocyte Disorders / МSD Manual:

blood poisoning;
diseases that suppress a person's immune system. For example, AIDS;
various diseases of the bone marrow, due to which the production of white blood cells decreases;
chemotherapy and radiation therapy. These treatments can damage the bone marrow.

What to do if your monocyte count is above or below normal

First of all, don't be nervous. A decrease or increase in the level of monocytes in itself is not dangerous. Perhaps this is generally a random temporary phenomenon.

Only a professional doctor can figure it out - the one who issued you a referral for a general blood test. The health care provider will evaluate other blood counts from the same test and relate them to your well-being, complaints, and symptoms. Perhaps he will offer to retake the analysis or undergo additional research. And only after that the preliminary diagnosis will be announced. Or, on the contrary, he will inform you that everything is in order with you - this is also completely possible.