Eosinophil

Eosinophil, a white blood cell belonging to the group of granular leukocytes (granulocytes), which is normally formed in the bone marrow. Eosinophils are found in the blood of mammals, amphibians, reptiles, birds, and fish. The protoplasm of the eosinophil is filled with large granules that stain intensely with acidic dyes, including eosin, which is why they were named eosinophils by Ehrlich. In humans, the eosinophil is somewhat larger than a neutrophil: the granulation of a mature normal eosinophil in a fixed smear consists of homogeneous, relatively uniform-sized acidophilic granules (see separate table, fig. 1). In addition, Liebreich discovered in them a small number of shiny, non-staining granules, the so-called a-granules. The granulation in some immature eosinophilic myelocytes is basophilic. In pathological eosinophils, small basophilic granules are often found among the eosinophilic granulation (see separate table, fig. 2). The nucleus of the eosinophil mostly consists of two segments, although nuclei with 4-5 segments are also encountered, as well as rod-shaped ones. In pathological cases, the nucleus of the eosinophil may remain unsegmented and retain a kidney-shaped or even round form (see separate table, fig. 3). The intravital formation of leukocyte granulation, including that of eosinophils, is called into question by many authors. Using the Vonwiller method during capillaroscopy with oil immersion, it has not yet been possible to detect granulation in human leukocytes. Saltykov, Nikolaev, and others consider eosinophilic granules to be phagocytized erythrocytes. In a fresh drop and when examined in a dark field, the granulation of eosinophils is coarse, shiny, and strongly refracts light. Upon the disintegration of human eosinophils, Charcot-Leyden crystals are produced. Petri and Neumann subjected eosinophil granulation to chemical analysis, according to which it consists of highly organized protein bodies that do not contain phosphorus, are relatively rich in iron, but lack a hematin group, and exhibit extremely high resistance to enzymes and various solvents. Müller detected from 2% to 4% lipoids in eosinophilic granules. When stained according to Zert and Goldman, they stain with Sudan. Eosinophils give an oxidase, peroxidase, and dopa reaction. The amoeboid motility of eosinophils is easily detected by processing a drop of blood according to Hewerden: after slightly smearing a drop of blood on a microscope slide, it is quickly placed in a moist chamber for 15 minutes in an incubator. Then, a little formalin is poured into the chamber; after 5 minutes, the preparation is rinsed with water and stained. The eosinophils are found to be fixed with the formation of pseudopodia. The same is observed in tissue cultures and when examining with a heated stage. In dogs, the granulation in some eosinophils consists of large, roundish formations of varying sizes, some of which sometimes fill almost the entire protoplasm (see separate table, fig. 5). In the rabbit, the leukocytes corresponding to the neutrophilic series of white blood cells in other animals are called pseudo-eosinophils (see separate table, fig. 4). In the protoplasm of pseudo-eosinophils, there is fine eosinophilic and coarse basophilic granulation. The latter predominates in immature forms. The number of eosinophils in a normal human fluctuates on average between 2-4%. When the number of eosinophils increases above 6%, it is called eosinophilia; when it decreases below 2%, it is called eosinopenia (hypoeosinophilia); and when they are absent from the blood (also when examined in a thick drop), it is called an-eosinophilia (see An-eosinophilia). Eosinophils can completely disappear from the circulating blood, despite the fact that they are found in large quantities in the bone marrow. Blood eosinophilia also does not always coincide with so-called tissue eosinophilia (e.g., eosinophilic infiltration of the mucous membrane of the bronchi, intestines, eosinophilic infiltration in lymphogranulomatosis, etc.). Eosinophilia is detected in various diseases of an anaphylactic nature, for example, in bronchial asthma, hay fever, Quincke's edema, migraine, and also upon parenteral administration of protein in cases producing the Arthus phenomenon, as well as in cases of hypersensitivity to medicinal or occupational chemical substances (insulin, ursol, etc.). Skin diseases, as well as muscle diseases, often result in high eosinophilia counts. Various helminthic diseases, especially trichinosis, cause eosinophilia. Eosinophilia in neuroses is associated with phenomena of irritation of the autonomic nervous system. Among infectious diseases, eosinophilia at the beginning of the disease process is observed, for example, in scarlet fever, while in other infectious diseases, eosinophilia is noted during the recovery period. Certain forms of chronic myelogenous leukemia produce extremely high eosinophil counts, but usually, moderate eosinophilia is observed. Splenectomy often results in prolonged eosinophilia. During liver therapy for pernicious anemia, an increase in the number of eosinophils to very significant figures (30-50%) is often observed.