Everyone knows that white blood cells - leukocytes - provide the body's immune response. They are the main neutralizers of toxins, poisons and antigens. One of the main indicators of blood is the leukocyte formula, which is determined in a blood test. But what it is, and what types of leukocytes are determined at the same time, not everyone knows. The article will present a general description of leukocytes and their types, methods of counting and deciphering the leukocyte blood formula.
General information
Leukocytes are white blood cells of amoeboid form with various forms of nuclei. They have sizes from 7 to 20 microns, and in 1 ml3 of blood they contain up to 8 thousand (for comparison, there are about 5 million erythrocytes in such a volume of blood).
Leukocytes live from 3 to 5 days, so they are constantly updated. They are formed from stem cells (the precursors of blood cells) in the red bone marrow, andalso the spleen and lymph nodes. Leukocytes end their life cycle in the liver and spleen, and in the presence of an inflammatory process at the site of its focus.
All these cells have the ability to phagocytosis (absorption of foreign objects), discovered by the world-famous scientist Ilya Mechnikov (1845-1916). Some leukocytes can penetrate through the walls of blood vessels into the intercellular tissue fluid and carry out their functions there. In addition, thanks to cytokines - organic substances that secrete leukocytes - they are able to exchange information and coordinate actions.
The number of leukocytes in the blood depends on many factors - the time of day, the state of the body, emotions, the presence of infectious diseases.
Types of white blood cells
There are 5 types of white blood cells in our blood:
- The most numerous are neutrophils. These leukocytes have a segmented nucleus (segmented or adult), which in young neutrophils has the appearance of a rod that has not yet been divided into segments (stab). They are the first to appear in the focus of infection and begin to fight it - they phagocytize antigens and bacteria.
- Lymphocytes are the most important link in the immune response. There are two types: T-lymphocytes destroy the affected cells and prevent the spread of infection; B-lymphocytes produce antibodies - biologically active proteins that bind to proteins of foreign objects (antigens on the surface of bacteria, protozoa,fungi and viruses) and make them recognizable and accessible to their main destroyers - monocytes and neutrophils. When compiling a leukocyte blood formula, T and B lymphocytes are counted together.
Not so numerous, but still important:
- Monocytes are large leukocytes that have a non-segmented eccentrically located nucleus and cytoplasm with a large number of lysosomes. In the bloodstream, they live up to a maximum of 40 hours, after which they settle in the tissues and turn into macrophages - cells that actively absorb antigens.
- Eosinophils are leukocytes with a bilobed nucleus. Their job is to fight parasites. And they are responsible for the development of an allergic reaction.
- The last type of white blood cells are basophils or basophilic granulocytes. There are few of them in the blood, they have an S-shaped nucleus and the largest sizes among leukocytes. Their granules contain histamine, serotonin, prostaglandin - mediators of inflammation and allergies. Thanks to them, poisons and toxins are blocked in the tissues, and they are also involved in the mechanism of blood clotting.
Norm and deviations
Normal indicators of the leukocyte formula of an adult are presented in the table above. At the same time, deviations from the norm can be both in one parameter and in several.
Deviations from the norm in the leukocyte formula are indicated by the following terms:
- With an increased level of a certain type of lymphocytes, the ending “oz” / “ez” or “ia” is added to their name. For example, monocytosis, basocytosis, eosinophilia.
- When the level of certain lymphocytes is reduced, the ending of "singing" is added. For example, monopenia, eosinopenia.
Form shift
In addition, when analyzing the leukocyte formula, the concept of its shift is used:
- Shift to the left means that the number of immature neutrophils (stab) and the appearance of young (metamyelocytes) and myelocytes are increased. This may indicate necrotic processes in tissues, inflammation, infection, poisoning. But such indicators can also appear after heavy physical exertion and eventually return to normal.
- Shift of the leukocyte formula to the right means that the number of immature neutrophils in the blood is reduced, and the number of segmented neutrophils is increased. Such indicators may indicate radiation sickness, pathologies of the kidneys and liver. Such a formula is not pathological for patients who have undergone blood transfusion.
Shift this result is called due to the fact that the calculation of the formula obeys a certain algorithm - young neutrophils are taken into account first, and then mature ones in ascending order. And the imbalance of their number "shifts" the leukocyte formula either in one direction or in the other.
How are they counted?
For quite a long time, the number of leukocytes in the blood was counted manually. This uses two methods:
- The four-field Schilling method - counting white blood cells in four areas of a blood smear.
- Filipchenko's three-field method - counting leukocytes in the initial, middle and final partsblood smear.
Modern analyzer devices allow you to calculate the leukocyte blood count with higher accuracy. Analyzers cover about several thousand leukocytes, while with manual counting, the leukogram covers up to 200 cells.
That is why, when choosing an institution where to donate blood for a leukogram, it is important to find out what tools the laboratory has.
Why is it prescribed and how is the study carried out?
General analysis with leukocyte formula can give an idea of:
- The body's ability to fight infection and evaluate the immune response.
- The severity of allergic reactions and the presence of parasites.
- Degrees of adverse effects of certain drugs and chemotherapy.
- Pathological processes in the blood (leukemia) and their diagnosis.
For a blood test with a leukocyte formula, both venous and capillary blood is suitable. For the accuracy of the analysis, it is necessary to prepare for it, namely:
- Do not drink alcohol the day before blood donation and do not smoke for at least half an hour before the test.
- Donate blood on an empty stomach, that is, do not eat at least 3 hours before the analysis. You can only drink still water.
Variability and clinical significance
As already mentioned, a leukogram is a rather variable analysis, which depends on gender, age and other characteristics of the body.
However, an increase in one kindleukocytes always comes at the expense of a decrease in their other type. And a comprehensive interpretation of the patient's leukocyte blood formula gives an overall picture of the pathological process, the likelihood of complications and predicting the development of the disease.
Analysis is often prescribed in conjunction with a general blood test, is required in preparation for surgery and during scheduled medical examinations.
Increasing performance
An increased number of neutrophils can indicate a variety of pathologies. Such a leukogram is typical for infectious diseases of bacterial, viral and fungal etiology, with elevated blood glucose levels in diabetes, oncology, pancreatitis, myocardial infarction, heavy metal poisoning. An increase in the number of neutrophils is observed with emotional, physical and painful stress, overheating and frostbite.
An increase in the number of leukocytes is characteristic of infections (mononucleosis, toxoplasmosis, cytomegalovirus, chickenpox, tuberculosis), blood pathologies, poisoning.
Monocytes in the blood are increased in patients with autoimmune diseases, malignant tumors, with severe phosphorus poisoning. This clinical picture is observed in chronic syphilis and tuberculosis.
An increase in eosinophils and basophils indicates the presence of an allergic reaction (bronchial asthma, eczema, food and drug allergies) and parasites, pathologies of the skin and lungs. Their level also increases in the acute course of an infectious disease.
Decline
A significant decrease in neutrophils in the patient's blood indicates an infectious disease (flu, hepatitis, measles), B-12 deficiency anemia and anaphylactic shock. It can also indicate sepsis, oncology and bone marrow metastases.
Decrease in leukocytes can indicate immunodeficiency states (AIDS / HIV), acute inflammation, kidney failure, radiation sickness.
Oncohematological pathologies, aplastic anemia and the acute course of an infectious disease significantly lower the number of monocytes.
A significant decrease in eosinophils is evidence of the onset of the inflammatory process, purulent infection, heavy metal poisoning, oncology of the bone marrow and lymph nodes.
Basophil levels are naturally lowered during ovulation, pregnancy and extreme stress. Pathology with such indicators is said to be when there is an infectious disease or Cushing's syndrome (excess hormones of the adrenal cortex).
Result
Modern blood test for leukocyte formula has high accuracy, objectivity and reproducibility. This analysis is today considered one of the most effective methods of blood examination.
Data on the number and types of leukocytes allows the doctor to diagnose and track the effectiveness of treatment for allergies, inflammatory processes, blood diseases and other pathological conditions.
The analysis is simple and fast, but the main thing is the choice of a medical institution with the necessaryequipment for accurate and high-quality compilation of leukogram.
