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Phagocytosis study
Medical expert of the article
Last reviewed: 05.07.2025
Phagocytosis is the absorption of large particles by a cell that are visible under a microscope (e.g., microorganisms, large viruses, damaged cell bodies, etc.). The process of phagocytosis can be divided into two phases. In the first phase, the particles bind to the membrane surface. In the second phase, the actual absorption of the particle and its subsequent destruction occur. There are two main groups of phagocyte cells - mononuclear and polynuclear. Polynuclear neutrophils are the first line of defense against the penetration of various bacteria, fungi, and protozoa into the body. They destroy damaged and dead cells, participate in the process of removing old red blood cells and cleaning the wound surface.
The study of phagocytosis indices is important in the complex analysis and diagnostics of immunodeficiency states: frequently recurring purulent-inflammatory processes, long-term non-healing wounds, tendency to postoperative complications. The study of the phagocytosis system helps in the diagnostics of secondary immunodeficiency states caused by drug therapy. The most informative for assessing the activity of phagocytosis are considered to be the phagocytic number, the number of active phagocytes and the index of phagocytosis completion.
Phagocytic activity of neutrophils
Parameters characterizing the state of phagocytosis.
- Phagocytic number: normal - 5-10 microbial particles. Phagocytic number is the average number of microbes absorbed by one blood neutrophil. Characterizes the absorption capacity of neutrophils.
- Phagocytic capacity of blood: normal - 12.5-25×10 9 per 1 liter of blood. Phagocytic capacity of blood is the number of microbes that neutrophils can absorb in 1 liter of blood.
- Phagocytic index: normal 65-95%. Phagocytic index is the relative number of neutrophils (expressed as a percentage) participating in phagocytosis.
- Number of active phagocytes: normal - 1.6-5.0×10 9 in 1 liter of blood. Number of active phagocytes - absolute number of phagocytic neutrophils in 1 liter of blood.
- Phagocytosis completion index: normal - more than 1. The phagocytosis completion index reflects the digestive capacity of phagocytes.
Phagocytic activity of neutrophils usually increases at the beginning of the development of the inflammatory process. Its decrease leads to chronicity of the inflammatory process and maintenance of the autoimmune process, since this disrupts the function of destruction and removal of immune complexes from the body.
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