Everyone knows that white blood cells - white blood cells - 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 by a blood test. But here is what it is, and what types of white blood cells are determined, not everyone knows. The article will present a general description of leukocytes and their types, methods for counting and decoding leukocyte blood counts.
general information
White blood cells are white blood cells of an amoeboid form with various shapes of nuclei. They have sizes from 7 to 20 microns, and in 1 ml 3 of blood they contain up to 8 thousand (for comparison, red blood cells in this volume of blood contain about 5 million).
White blood cells live from 3 to 5 days, so they are constantly updated. They are formed from stem cells (precursors of blood cells) in the red bone marrow, as well as the spleen and lymph nodes. Leukocytes in the liver and spleen end their life cycle, 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 world-famous scientists Ilya Mechnikov (1845-1916). Some leukocytes can penetrate through the walls of blood vessels into the intercellular tissue fluid and already carry out their functions there. In addition, thanks to cytokines - organic substances that secrete leukocytes - they are capable of exchanging information and coordinating actions.
The number of white blood cells 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
In our blood, white blood cells are represented by 5 types:
- The most numerous are neutrophils. These leukocytes have a segmented nucleus (segmented or adult), which in young neutrophils has the appearance of a stick 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 - phagocytose antigens and bacteria.
- Lymphocytes are an essential part of 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 count, T and B lymphocytes are counted together.
Not so numerous, but also important:
- Monocytes are large leukocytes that have an unsegmented eccentrically located nucleus and a cytoplasm with a large number of lysosomes. They live in the bloodstream for a maximum of 40 hours, after which they settle in the tissues and turn into macrophages - cells that actively absorb antigens.
- Eosinophils are white blood cells with a bilobed nucleus. Their task is to combat parasites. And they are responsible for the development of an allergic reaction.
- The last type of white blood cells is basophils or basophilic granulocytes. There are few of them in the blood, they have an S-shaped nucleus and the largest sizes among white blood cells. Their granules contain histamine, serotonin, prostaglandin - mediators of inflammation and allergies. Thanks to them, poisons and toxins are blocked in the tissues, and they also participate in the blood coagulation mechanism.
Norm and deviations
Normal indicators of the leukocyte formula of an adult are presented above in the table. In this case, 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 elevated level of a certain type of lymphocyte, the term “oz” / “ez” or “ia” is added to their name. For example, monocytosis, basocytosis, eosinophilia.
- With a reduced level of certain lymphocytes, the ending of “singing” is added. For example, monopenia, eosinopenia.
Formula shift
In addition, in the analysis of the leukocyte formula, the concept of its shift is used:
- A shift to the left means that the number of immature neutrophils (stabs) and the appearance of young (metamyelocytes) and myelocytes are increased. This may indicate necrotic processes in the tissues, inflammation, infection, poisoning. But such indicators may appear after heavy physical exertion and eventually return to normal.
- Shifting 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. This formula is not a pathology for patients undergoing a blood transfusion.
This result is called a shift due to the fact that the calculation of the formula obeys a certain algorithm - first, young neutrophils are taken into account, and then mature in ascending order. And the imbalance of their number “shifts” the leukocyte formula either in one direction or in the other.
How do they count?
For a fairly long time, the number of white blood cells in the blood was counted manually. In this case, two methods are used:
- The four-floor Schilling method is a white blood cell count in four sections of a blood smear.
- Three-field method Filippchenko - counting white blood cells in the initial, middle and final part of a blood smear.
Modern instrument analyzers allow you to calculate the white blood cell count with higher accuracy. The analyzers cover the order of several thousand white blood cells, while with manual counting, the leukogram covers up to 200 cells.
That is why when choosing an institution where to donate blood to a leukogram, it is important to find out what tools the laboratory owns.
Why is it prescribed and how is the study conducted?
A general analysis with a 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 the analysis of blood with a leukocyte formula, both venous and capillary blood are suitable. For the accuracy of the analysis, it is necessary to prepare for it, namely:
- Exclude the use of alcohol a day before blood donation and do not smoke at least half an hour before analysis.
- Donate blood on an empty stomach, that is, do not eat at least 3 hours before analysis. You can drink only non-carbonated water.
Variability and Clinical Importance
As already mentioned, a leukogram is a rather variable analysis, which depends on gender, age and other characteristics of the body.
Nevertheless, an increase in one type of white blood cells always comes at the expense of a decrease in their other type. And a comprehensive decoding 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.
The analysis is often prescribed in conjunction with a general blood test, is mandatory in preparation for surgical operations and planned medical examinations.
Performance enhancement
An increased number of neutrophils may indicate many pathologies. Such a leukogram is characteristic of 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 pain loads, overheating and frostbite.
An increase in the number of leukocytes is characteristic of infections (mononucleosis, toxoplasmosis, cytomegalovirus, chicken pox, tuberculosis), blood pathologies, poisoning.
Monocytes in the blood are increased in patients with autoimmune diseases, malignant tumors, and 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, skin and lung pathologies. Their level rises in the acute course of an infectious disease.
Performance reduction
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.
A decrease in leukocytes may indicate immunodeficiency states (AIDS / HIV), acute inflammatory process, renal failure, radiation sickness.
Oncohematological pathologies, aplastic anemia and the acute course of an infectious disease significantly reduce 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 bone marrow and lymph nodes.
Basophil levels are naturally reduced during ovulation, pregnancy, and severe stress. With such indicators, pathology is said to be when there is an infectious disease or Cushing's syndrome (excess hormones of the adrenal cortex).
Total
A 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 testing.
Data on the number and types of leukocytes gives the doctor the opportunity to diagnose and monitor the effectiveness of treatment for allergies, inflammatory processes, blood diseases and other pathological conditions.
The analysis is simple and quick, but the main thing is the choice of a medical institution with the necessary equipment for accurate and high-quality preparation of leukorgamma.