Introduction:
White blood cells are a group of structurally varying nucleated cells, where all these different cells are grouped into white blood cells. These white cells are a part of the blood composition and are seen along with the red blood cells in the bloodstream throughout life. The white blood cells are essential in fighting against all kinds of infections affecting the system. Because of this reason, the number of white blood cells present in the systemic circulation is most important as it determines the composition of the body’s immunity levels. A differential blood test is done by determining the components and type of cells present. Here, a differential blood cell count is a laboratory method of measuring the amount of each type of blood cell and its percentage present per cubic millimeter of blood, giving complete knowledge about the amount of blood cells in the body.
How Is Differential Blood Count Done?
White blood cells, also called leukocytes, are examined using various techniques with different levels of sophistication and complexity. This test analyzes the quality and quantity of the white blood cells in the laboratory. Neubauer's test is one of the simplest tests for counting the level of white blood cells, and it is a manual method of counting the white cells present. Recently, this test has also been done with automation counters, and this method is highly preferred and most commonly used, providing quicker outcomes and high accuracy. The procedure is done by thinly spreading a blood drop over a microscopic slide, which is air-dried and stained with Romanofsky’s stain, also called Wright stain. The stained cells are placed under a microscope and counted up, grouping them around two hundred cells. With recent technological developments, this automation enables one to read the count and its structural morphology.
What Are the Types of White Blood Cells?
White blood cells are a collection of different forms of cells, and they are called:
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Neutrophils: These are the most predominantly existing white blood cells, known as the first line of defense cells. These cells rush up to the site of infection or inflammation. These cells club up like nets with a neutrophil elastase protein to form neutrophil extracellular traps (NET). The other organic components like proteins, histones, and enzymes are encapsulated in the NET. These cells help to engulf the bacteria and foreign particles entering the body.
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Lymphocytes: Lymphocytes, again, are one of the primary cells in the immune system. These cells provide targeted immune responses by attacking the invading microorganisms. These cells are in blood and lymph and are simultaneously seen in lymphoid organs such as the thymus, spleen, and lymph nodes. Lymphocytes are cells divided into two classifications: T or B cells. The cells structurally appear as dark purple stained nuclei under the microscope when stained with a white stain. These cells also show an abundance in the level of cytoplasm. T and B lymphocytes can be differentiated using tests like Enzyme-Linked Immunospot Assay. T-cells are cells that play a role in cell-mediated immunity. Depending on the type of t-cell receptors on the cellular surface, these cells identify as B-cells and natural killer cells. The deficiency of T-lymphocytes is seen in AIDS (acquired immunodeficiency syndrome), HSV (herpes simplex virus), mycobacterial infections, and cancers like lymphomas. B-cells are cells that are mediated by humoral response, characterized by the production of antibodies. The B-cells secrete an enzyme called cytokine (inflammatory mediating factors). The B-cells release antibodies depending on the specific antigen receptors. B-cell-related disorders are usually autoimmune diseases like scleroderma, systemic lupus erythematosus (SLE), multiple sclerosis, rheumatoid arthritis, and cancers like Hodgkin’s lymphoma and non-lymphoma.
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Monocytes - Monocytes are cells that are involved in the body’s innate immune system, which involves mainly acting against infections. Monocytes are classified into two types: macrophages and dendritic cells. These macrophages clean up the system by eating the dead cells of the infective bacteria, which is mediated by chemokine receptors. Monocytes are seen in infections such as multiple sclerosis, Alzheimer's disease, muscle injury, and liver diseases. Monocytes are also seen in the regeneration of cells in conditions like fibrosis and tumor progression.
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Eosinophils: These are the antiallergic cells. They are immunity-modulated and seen to be effective against parasitic infections. Eosinophils are seen in long-term allergic infections.
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Basophils - Basophils are cells that release enzymes called histamine, which are involved in allergic conditions and chemical-induced reactions like asthma.
How Is the Clinical Significance of Differential Blood Count Done?
The clinical significance of white blood cells is of great importance as it pertains to the body’s immunity. Due to this, any infection or an external object entering the body battles with the white blood cells as the body’s preventive measure. However, the range of white blood cells in the body should also be adequate as an increase or decrease of the white blood cells for a longer duration can harm the body. The white blood cell differential count assesses infection, anemia, and leukemia. This test is clinically done to assess the level of the entire white blood cells like neutrophils, eosinophils, monocytes, basophils, and lymphocytes, which indicate allergic, inflammatory, infective, or tumor progression factors.
Conclusion:
White blood cell count is crucial as it is the prime indicator of any infection or illness. The white blood cell count helps to asses all the cells present under the white blood cells, their characteristic features, etc., which helps to have an idea regarding the presence or progression of infection, the extent of the body’s capacity to fight against such conditions, treatment plan to be done and the rate of recovery to be done. Also, as these are used regularly, they are considered the first line of diagnosis in differentiating disorders of the white blood cells or the accumulation of all blood cells. One of the beneficial effects of white blood cell count is that it is cost-effective, can be accessible with minimal equipment, and is accessible for all.
