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Diseases of eosinophils: causes, symptoms, diagnosis, treatment
Last reviewed: 23.04.2024
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Eosinophils are granulocytes and are derived from the same precursor as monocyte-macrophages, non-atrophils and basophils. The exact function of eosinophils is unknown. As phagocytes, eosinophils are less effective than nontrophils in the destruction of intracellular bacteria. There is no direct evidence indicating that eosinophils destroy vivo parasites , but they are toxic to helminths in vitro, and eosinophilia usually accompanies helminth infections. Eosinophils are able to modulate immediate-type hypersensitivity reactions by degrading or inactivating mediators released by mast cells such as histamine, leukotrienes (which can cause vasoconstriction and bronchospasm), lysophospholipids, and heparin. Prolonged eosinophilia can lead to tissue damage through mechanisms that until now are completely unclear.
Eosinophilic granules contain the main main protein and eosinophilic cationic protein, which are toxic to a number of parasites and mammalian cells. These proteins bind heparin and neutralize its anticoagulant activity. Eosinophilic neirotoxin can cause severe damage to the myelin sheath of neurons. Eosinophilic peroxidase, which is significantly different from other granulocyte peroxidase, generates oxidative radicals in the presence of hydrogen peroxide and halide compounds. Charcot-Leiden crystals, consisting mainly of phospholipase B, are localized in sputum, tissues and feces in diseases accompanied by eosinophilia (eg, asthma, eosinophilic pneumonia).
Normally, the number of eosinophils in the blood is less than 350 / μl, with daily fluctuations inversely proportional to the level of plasma cortisol; The highest level is at night, the lowest in the morning. The half-life of eosinophils in circulation is from 6 to 12 hours, most of these cells are in tissues (for example, the upper respiratory tract, GIT, skin, uterus).
The formation of eosinophils is probably regulated by T cells by secretion of such hematopoietic growth factors as granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 3 (IL-3) and interleukin 5 (IL-5). Factors GM-CSF and IL-3 increase the production of other myeloid cells, IL-5 stimulates the formation of only eosinophils.
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