What are the leukocytes responsible for and what is the reason for the change in their level in the blood?

Almost everyone knows in general outline what leukocytes are. These are large elements of blood in the form of balls that do not have color. They are often called white blood cells( or corpuscles).In the human body, leukocytes of different types function, differing in structure, origin and purpose. But they are all the main cells of the immune system and fulfill one of the most important tasks - protection from external and internal "enemies".White cells can actively move not only in the bloodstream, but also pass through the vascular walls, penetrate into tissues, organs, and then return to the blood. Having found danger, white blood cells quickly arrive in the right place, first moving with the blood, and then moving independently thanks to the pseudopods.


White bodies are capable of capturing harmful agents and digesting them, after which they themselves die. The process of destroying "enemies" is called phagocytosis, and the cells that carry it out are called phagocytes. Leukocytes are responsible not only for the destruction of foreign bodies, but also for the purification of the body, that is, for the disposal of unnecessary elements: the remains of pathogenic microbes and dead white cells.

Another function of leukocytes is the production of antibodies for the neutralization of pathogenic elements. Antibodies make a person unresponsive to some of the diseases that he previously suffered from.

Leukocytes affect the metabolism, and also supply tissues and organs with missing hormones, enzymes and other substances.

Types of leukocytes and the functions of each of them

The white cells are divided into granular( granulocytes) and non-grained( agranulocytes) in shape and structure. The former have a granular cytoplasm and segmented large nuclei. These include neutrophils, basophils and eosinophils, which differ among themselves in susceptibility to dyes. In agranulocytes, granularity is absent, and the nucleus is simple and non-segmented. These are monocytes and lymphocytes.

The laboratory assistant counts the leukocyte formula
Under a microscope in a blood smear, it is easy to see how the leukocytes move


This is a large group of white blood cells that form in the bone marrow and are related to phagocytes. Cells in which nuclei with segments are called mature, or segment-nuclear. Neutrophilic leukocytes with an elongated nucleus in the form of a rod are stabbed, or immature. There are even younger forms - metamyelocytes, which are called young. Most of all in the blood of mature cells, immature - much less, and very few young forms. The ratio of immature and segmented neutrophils shows how intensively the process of hematopoiesis passes. For example, with significant blood loss in the body, a large number of cells are formed, which do not have time to ripen, thus, the number of young forms increases in the blood.

The main task of neutrophils is to participate in phagocytosis, that is, the absorption and digestion of foreign agents, as well as the ability to produce antimicrobials and to carry out detoxification.

When pathogens enter the body, neutrophils accumulate in large numbers at the site of infection. Capturing and destroying microorganisms, they die, and as a result, pus is formed. Their content in the blood - 1-5% of the total number of leukocytes.


They contain heparin and histamine, are able to migrate from the blood into the tissues. They take part in the development of allergic reactions. Their number is 0.5% of all leukocytes.


Take part in the formation of allergic reactions, remove the resulting excess of histamine. If the body has helminths, eosinophils penetrate the intestine, are destroyed there and release toxic substances for helminths. Their content in the blood - 1-5% of the total number of leukocytes.


They begin to perform the function of absorbing and destroying pathogens after they turn into large cells - macrophages. Monocytes function in all systems and organs, can capture particles equal in size. Compose from 1 to 8% of the number of all white blood cells.


These are the most important defenders, producing antibodies for neutralizing "enemies".Lymphocytes constantly patrol the body's systems for the presence of foreign and mutated cells. Macrophages move around the body, collect suspicious elements and report them to lymphocytes. These cells account for approximately 35% of all leukocytes.

Norm of white blood cells

Normally in adult men and women, the number of white blood cells is from 4000 to 9000 per milliliter of blood. Slightly elevated leukocytes in healthy individuals may be the norm of .Their level may vary depending on the time of day, physical activity, eating, emotional stress, pain, hypothermia, or overheating, as well as before and during pregnancy. If the leukocytes in the blood significantly go beyond the norm in one direction or another, then it means that the pathology has developed. Decoding of the blood test usually takes into account the leukocyte formula - the ratio( in percent) of different types of white cells.

What is the reason for the increase?

A condition in which a lot of white blood cells in the blood and their level is more than 9000 per 1 ml of blood is called leukocytosis. If leukocytes are increased, this means that there are:

  • infectious diseases;
  • inflammatory processes;
  • leukemia;
  • cancers;
  • blood loss;
  • the effects of taking certain medicines.

Increased neutrophils are observed in diseases such as:

  • pneumonia;
  • abscess;
  • angina;
  • pyelonephritis;
  • appendicitis;
  • sepsis;
  • meningitis.

An increase in the number of basophils is rare. These cases include allergies, certain types of leukemia, thyroid insufficiency, and lymphogranulomatosis.

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Test tubes with blood

Leukocyte blood formula

Eosinophils increase with the following diseases:

  • bronchial asthma;
  • infections with helminths;
  • for allergic dermatitis;
  • drug allergy;
  • some types of leukemia;
  • tumor processes;
  • nodular periarteritis.

High lymphocytes are observed in the blood test for leukemia and infections such as syphilis, viral hepatitis, tuberculosis, whooping cough, mononucleosis and others.

Monocytes increase in the following cases:

  • for infectious diseases: tuberculosis, syphilis, brucellosis, mononucleosis, malaria;
  • in autoimmune processes: sarcoidosis, lupus erythematosus, vasculitis, rheumatoid arthritis;
  • for lymphogranulomatosis, leukemia.

Why go down?

Lowered leukocytes are called in medicine by leukopenia. In this case, their level is below the norm and is less than 4000 cells per 1 ml of blood. Low leukocytes are a characteristic phenomenon for such pathologies as:

  • , oncological diseases;
  • leukemia at an early stage;
  • anemia( B12-deficient);
  • radiation exposure;
  • some infections;
  • reception of hormonal agents;
  • increased function of the spleen.

If neutrophils are lowered, there is a possibility of developing typhoid, rubella, influenza, hepatitis, measles, some forms of tuberculosis. Reduction of these leukocytes is possible with systemic lupus erythematosus, chemical and radiation effects, with certain types of anemia and leukemia.

Reduced lymphocytes are usually observed in severe viral infections, immunodeficiencies, malignant tumors, and glucocorticoids.


Determining the level of leukocytes in the blood is of great importance in the diagnosis. Low or high leukocytes can signal a pathological reaction taking place in the body. Correct interpretation of the blood test allows for early diagnosis and more effective treatment.