What is a White Blood Cell?

White blood cells (English name: leukocyte, white blood cell, WBC for short) are colorless, spherical, and nucleated blood cells. The total number of normal adults is (4.0 to 10.0) x 10 ⁹ / L, which can vary within a certain range due to different times of the day and the functional status of the body.

White blood cells (English name: leukocyte, white blood cell, WBC for short) are a type of colorless, spherical, nucleated blood cells. The total number of white blood cells in normal adults is (4.0 10.0) × 10 ⁹ / L, which can vary within a certain range due to different times of the day and different functional states of the body. Leukocytes are not a uniform cell population. They can be divided into three categories according to their morphology, function, and source: granulocytes, monocytes, and lymphocytes. Granulocytes can be divided into different types of granules in the cytoplasm. Neutrophils, eosinophils and basophils ^[1]

Most white blood cells stay in the blood only a little. Then enter the organization to play a role. Therefore, white blood cells can stretch out the pseudofoot for deforming movement. With this movement, white blood cells can be squeezed out from the gap of capillary endothelial cells and enter the tissues around the blood vessel. This process is called white blood cell dialysis (diapedesis). Leukocytes that have exuded can also move around in the tissue by virtue of deforming movements, and have the characteristic of moving toward certain chemicals, called chemotexis. Chemicals that attract white blood cells to directional movement are called chemokines. Some white blood cells also have phagocytosis, which can swallow and kill or degrade pathogens and tissue fragments. Some leukocytes can also secrete a variety of cytokines such as interleukins, interferons, and tumor necrosis factor, which are involved in the regulation of inflammation and immune response. ^[1]

The main function of leukocytes is defense. Different types of white blood cells participate in the body's defense response in different ways.

There are five types of white blood cells in the blood. From small to large, they are:

The "National Clinical Laboratory Operation Regulations" compiled by the Department of Medical Affairs of the Ministry of Health of China, the normal reference values for the adult leukocyte classified count are as follows ^[4]

Leukocyte neutrophil

Neutrophil pathological increase

In acute purulent infections, the degree of neutrophil increase depends on the type of infected microorganisms, the extent of the infection, the severity of the infection, and the patient's ability to respond. If the infection is very limited and mild, the total number of white blood cells can still be normal, but the percentage of lobulated nuclei can be increased during the classification test; during moderate infections, the total number of white blood cells has increased by more than 10 × 10 ⁹ / L, with mild nuclear images left The total number often increases significantly in severe infections, up to more than 20 × 10 ⁹ / L, with a significant shift in the left nucleus. Leukocytes rapidly increase after spleen rupture or ectopic pregnancy fallopian tube rupture, often reaching (20-30) × 10 ⁹ / L. The increased cells are mainly neutrophil neutrophils. This may be related to stress, internal hemorrhage, and transient hypoxia. When chemicals such as sleeping pills and dichlorvos are poisoned, the number of common white blood cells increases, even up to 20 × 10 ⁹ / L or higher. Leukopenia is also common in metabolic poisonings such as diabetic ketoacidosis and chronic nephritis uremia. Neutrophil neutrophils are the main ones. Leukocytes show a long-term persistent increase, most commonly in myeloid leukemia, and can also be seen in the late stages of various malignancies. At this time, not only the total number often reaches (10-20) × 10 ⁹ / L or more, and there may be more The obvious nuclear shift to the left is a so-called leukemia response. ^[5]

Neutropenia

Certain infections, such as typhoid fever, paratyphoid fever, malaria, and influenza, can cause leukopenia; certain blood diseases, such as aplastic anemia, show a "three low" performance; ionizing radiation (such as X-rays, etc.), long-term use of chlorine After mycin, leukopenia can be reduced by inhibiting mitosis of bone marrow cells; autoimmune diseases such as systemic lupus erythematosus, etc., are reduced due to leukocyte destruction caused by autoimmune antinuclear antibodies; splenomegaly caused by various reasons Visible leukopenia. ^[5]

Leukocyte eosinophil

It has phagocytosis and chemotactic effects, and increased eosinophil response is seen in bronchial asthma, angioedema, food allergy, and psychosis. When intestinal parasite antigens come into contact with IgE-bound mast cells in the intestinal wall, the latter is degranulated to release histamine, resulting in an increase in eosinophils. Prognosis and measurement of adrenal function in patients with surgery and burns. Tumor increase is seen in malignant diseases of the lymphatic system, blood diseases, chronic leukemia and so on. Patients with chronic myelogenous leukemia often have eosinophils as high as 10% or more, and juvenile types can be seen. Eosinophilic reduction is seen in typhoid fever, paratyphoid fever, severe tissue damage after surgery, and the use of adrenocortical hormone or adrenocorticotropic hormone, which generally has little clinical significance. ^[5]

Leukocyte basophils

With chemotaxis and weak phagocytosis. Increased in chronic myeloid leukemia, Hodgkin's disease, cancer metastasis, lead and bismuth poisoning. Rarely, basophilic leukemia is abnormally increased, up to more than 20%, and is mostly naive. Increased bone marrow fibrosis and some metastatic cancers are also seen. ^[5]

Leukocyte lymphocyte

The main function of lymphocytes is to participate in humoral immunity, cellular immunity and secretion of lymphokines. Lymphocytic is found in acute and chronic lymphocytic leukemia; certain infections: such as viral infectious diseases, bacterial infections (such as pertussis), and the recovery period of tuberculosis infection. If a rejection occurs after kidney transplantation, the absolute value of lymphocytes increases in the early stage of rejection. The former type of lymphocytic leukemia and leukemia lymphosarcoma is mainly chronic leukemic mature lymphocytes, while the acute type is mainly prolymphocytic lymphocytes, which can increase the total number of white blood cells. Premature lymphocytes. Newborn babies and children are physiologically increased.

Lymphopenia is mainly seen in people who have been exposed to radiation for long periods of time and who have been treated with adrenocortical hormone or corticotropin. In severe purulent infections, lymphocytes are relatively reduced due to a marked increase in neutrophils. ^[5]

Leukocyte monocyte

Normal children have slightly more monocytes in the peripheral blood than adults, with an average of 9%, and infants 2 weeks after birth can exhibit physiological monocytes, which can reach more than 15%.

Pathological increase is seen in some infections. Such as subacute infective endocarditis, malaria, black fever, etc .; monocytes can also be seen in the recovery period of acute infections; in active pulmonary tuberculosis such as severe invasive and miliary tuberculosis, monocytes in the blood can be significantly increase. During the recovery period of agranulocytosis, there is a transient increase in monocytes, malignant histiocytosis, and an increase in naive monocytes and an increase in mature types in lymphoma. In addition to anemia, leukocytopenia, etc. in myelodysplastic syndromes, nuclear cells are often increased in the classification of leukocytes. ^[5]