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Children's immunologist

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Investigation of phagocytosis

Alexey Portnov, medical expert
Last reviewed: 19.11.2021

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Phagocytosis is the absorption by the cell of large particles visible in a microscope (for example, 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 surface of the membrane. In the second phase, the actual absorption of the particle and its further destruction occur. There are two main groups of phagocyte cells - mononuclear and polynucleated. Polynuclear neutrophils constitute the first line of protection against the entry into the body of a variety of bacteria, fungi and protozoa. They destroy the 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 immunodeficient conditions: often recurrent purulent-inflammatory processes, long-term healing wounds, propensity to postoperative complications. The study of the phagocytosis system helps in the diagnosis of secondary immunodeficiency states caused by drug therapy. The most informative for assessing the activity of phagocytosis is the phagocytic number, the number of active phagocytes and the index of completeness of phagocytosis.

Phagocytic activity of neutrophils

Parameters characterizing the state of phagocytosis.

Phagocytic number: the norm is 5-10 microbial particles. The phagocytic number is the average number of microbes absorbed by a single blood neutrophil. Characterizes the absorption capacity of neutrophils.
Phagocytic blood capacity: the norm is 12.5-25 × 10 ⁹ per 1 liter of blood. Phagocytic blood capacity is the number of microbes that can absorb neutrophils 1 liter of blood.
Phagocytic index: the norm is 65-95%. The phagocytic index is the relative amount of neutrophils (expressed as a percentage) involved in phagocytosis.
The number of active phagocytes: the norm is 1.6-5.0 × 10 ⁹ in 1 liter of blood. The number of active phagocytes is the absolute number of phagocytic neutrophils in 1 liter of blood.
Index of completeness of phagocytosis: the norm is more than 1. The index of completeness of phagocytosis reflects the digesting ability of phagocytes.

Phagocytic activity of neutrophils usually increases at the onset of the inflammatory process. Its reduction leads to chronic inflammation and maintenance of the autoimmune process, as the function of destruction and removal of immune complexes from the body is disrupted.

trusted-source [1], [2], [3], [4], [5], [6]

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