What is leukocytosis

White blood cells are part of the immune system and can be produced by bone marrow hematopoietic stem cells. In addition to blood, white blood cells are found in the lymphatic system, spleen, tonsils, and other tissues of the body. When the human body is uncomfortable, it is often manifested by a significant change in the number of white blood cells. Among them, the increase in the number of white blood cells (counts) is a matter of great concern.

White blood cells can be subdivided into neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Counting these five types of cells separately is called the white blood cell classification (count) number. Normal range of white blood cell count: adult (4.0 ~ 10.0) × 10 9 / L; newborn (15-20) × 10 9 / L; 6 months to 2 years (11-12) × 10 9 / L. Its clinical significance is: Leukocyte count above the upper limit of the reference range is called leukocytosis, and below the lower limit of the reference range is called leukocytopenia.

The increase or decrease of leukocytes is mainly affected by the number of neutrophils, followed by the number of lymphocytes. The reasons that affect the number of leukocytes are divided into physiological reasons and pathological reasons. granulocyte

The cytoplasm of granulocytes contains a number of tiny cystic granules, and a variety of enzymes are stored in the granules. According to the staining properties of the granules, they can be divided into: neutrophils, which account for 70% to 80% of the total number of white blood cells. The first cell to actively participate; eosinophils, which can help the body fight against allergens that cause allergies, also have the ability to swallow; basophils, which mainly trigger allergic reactions, release histamine and cause smooth muscle contraction and vasodilation Wait.

Neutrophils are seen in diseases such as acute infections (especially Gram-positive cocci infections), severe trauma, large-scale burns, leukemia, and malignancies (such as liver and stomach cancers). Under physiological conditions, changes in peripheral white blood cell counts and neutrophils may also occur: higher in the afternoon than in the morning, after a full meal or shower, high temperature or severe cold, etc. may temporarily increase it. Studies have found that women of childbearing age have higher neutrophil counts than men and that they differ during the menstrual cycle. Pregnancy results in a significant increase in the number of neutrophils, and further increases during and after childbirth. Vigorous exercise can double the neutrophil count by altering the distribution of white blood cells in the circulation. Newborn white blood cell count is high, average is about 15 × 10 9 / L, the highest can reach more than 30 × 10 9 / L, it will drop to about 10 × 10 9 / L after 3-4 days , and it will be maintained for about 3 months. Gradually reduced to adult levels.


Aneutrophils include lymphocytes and monocytes.

Lymphocytes: Usually found in the lymphatic system, the blood contains 3 types of lymphocytes: B cells, T cells, and natural killer cells. B cells can produce antibodies that bind pathogens. CD4 (an immune cell) + T cells cooperate with the immune response. CD8 (a glycoprotein on the surface of T cells) + T cells and natural killer cells can kill virus-infected somatic cells. .

Lymphocytes increased when the lymphocytes were greater than 5 × 9 / L. The proportion of lymphocytes in childhood is high, accounting for 35% at birth, and up to 50% after 4-6 days; to 6-7 years of age, the proportion of lymphocytes gradually decreases, and the percentage of lymphocytes at this stage is higher than that of adults, which is a physiological increase . Pathological increase is found in infectious diseases caused by viruses or certain bacilli, lymphocytic malignant diseases, aplastic anemia, agranulocytosis, host-to-graft response, or graft-to-host response.

Monocyte: A small monocyte in the blood, but once it leaves the blood vessel, it will turn into macrophages, which can swallow a large number of bacteria at any time. Monocytes have the “cleansing” function of neutrophils, but they live longer than neutrophils because they have other responsibilities. Mononuclear cells and macrophages pass the antigenic fragments of pathogens to T cells so that the pathogens can be recognized again and killed or accelerate the body’s immune response.

In short, the obvious increase in the number of white blood cells is a very complex issue. We don’t have to worry about the temporary increase caused by physiological factors, but we must not ignore the pathological increase.