Monocytes are white blood cells and are the largest blood cells in our bloodstream. Their level in relation to the norm is checked in the blood count test with a smear. They are marked with the MONO abbreviation on the printout. Monocytes protect our immunity - they have, inter alia, the ability to phagocytose bacteria and to produce various mediators of the immune response, such as, for example, interferon. A blood count with a smear may indicate that there are too many monocytes in the patient's blood or that they are below normal - the causes of such abnormalities can be both infections and even cancer.

Monocytes(marked in morphology asMONO ) are produced in the bone marrow, from where they enter the blood, and then reach various organs of the body and become macrophages. Monocytes belong to leukocytes, and these play an extremely important role - they are the guardians of the human body's immunity.

Leukocytes are a fairly large group of blood cells that differ in structure and function. The basic division of white blood cells includes granulocytes (which include neutrophils, basophils and eosinophils) and agranulocytes (which include lymphocytes and monocytes).

Each of these types of white blood cells plays an important role - for example, lymphocytes are responsible for the production of antibodies, and eosinophils take part in the fight against parasites entering the body. What is the role of the blood cells we know as monocytes?

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What are monocytes? Characteristics of monocytes

Monocytes are generally the largest of all blood cells in human blood. Typically theirdimensions reach 10-20 micrometers , but there are also larger monocytes that have even40 micrometers(for comparison, the diameter of an average erythrocyte, i.e. a red blood cell is about 7 microns).

Among the characteristic features of monocytes, the most important is that these cells have a large number of lysosomes and mitochondria, as well as the extensive structure of the Golgi apparatus (these cell organelles allow monocytes to perform the functions assigned to them).

The kernel also attracts attentioncell monocytes - it is monocyte-shaped and typically has an oval, sometimes referred to as kidney-shaped, shape.

Monocytes: where are these white blood cells formed?

Monocytes, like other blood cells, are produced primarily in the bone marrow. These white blood cells are synthesized through a complicated process known asmonocytopoiesis .

The precursor of monocytes, like other leukocytes, are stem cells present in the bone marrow. The initial stage of production of monocytes and the other white blood cells, neutrophils, is the same. Eventually, however, after passing the monoblast and promonocyte stages, monocytes are formed, which are released from the bone marrow into the blood.

Monocytopoiesis can be stimulated by various factors. granulocyte macrophage growth factor (GM-CSF) and interleukin-6.

Functions of monocytes

Monocytes, as mentioned before, pass from the bone marrow into the blood, but they do not circulate in the bloodstream for a long time. After 1-3 days, this type of white blood cell travels to various organs of the body, most of them - even half of the total monocyte population in the body - accumulate in the spleen.

There is a certain difficulty here, the monocytes that reach the target tissues transform into their final form and then they are called macrophages.

The functions of monocytes are distinguished by at least a few. First of all, these cells - residing in various organs in the form of macrophages - are designed to phagocytose (that is, to simplify, devour) both unnecessary cells and tissue debris, as well as pathogenic microorganisms.

An interesting feature of these cells is that they have incredible migratory capacity - in a situation where the body develops an immune response, monocytes can migrate to even very distant regions of the body. These cells can even cross the walls of blood vessels - this is possible due to the fact that monocytes are characterized by the ability to so-called. diapapedises.

Monocytes are able to react to mediators of immune reactions, but they can also produce various such substances themselves. Tumor necrosis factor (TNF) and various interleukins, such as interleukin-1 and interleukin-12, are most often mentioned among those that can be released by this type of white blood cell. Yet another function that monocytes and macrophages can perform is to present antigens to various other cells of the immune system.

Monocytes: norms

To assess the number of monocytes, a peripheral blood smear is performed. On the result of thistests monocyte parameters are abbreviated as MONO.

Adult monocyte normcan be reported both as a number and as a percentage. In the case of the former, the amount of 30 to 800 monocytes per microliter of blood is considered correct. As for the percentage of these cells among all leukocytes, the result is from 4 to 8% as normal.

The norm of monocytes in childrenis basically similar to that in adults, however, in this group of patients the norm is sometimes also slightly higher than the values ​​given above.

Different laboratories have slightly different standards for different tests - before interpreting the result, you should always check which values ​​in a given laboratory are considered correct.

Excess monocytes in the blood. Elevated monocytes - what do they show?

A condition in which a patient has too many monocytes in their blood is calledmonocytosis . There are many reasons for the excess of monocytes, this disorder can be caused by:

  • hematological conditions (such as acute monocytic leukemia, chronic leukemias or Hodgkin's disease)
  • various infections (both bacterial and viral - an example of an entity that is particularly related to monocytosis is mononucleosis)
  • inflammatory bowel diseases (e.g. ulcerative colitis)
  • chronic, severe stress
  • liver disease
  • use of various medications (e.g. steroids)
  • condition after spleen resection

Monocytes below normal - causes. Monocytes too low

The opposite of the above-described situation of monocyte deficiency is referred to asmonocytopenia . There are definitely fewer causes of this problem, it may occur, among others, in the course of some infectious diseases or in patients with aplastic anemia.

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