Erythrophagia

Erythrophagia, erythrophagia, phagocytosis of erythrocytes. Under normal conditions, the destruction of senescent erythrocytes in the animal organism occurs through their being engulfed by cells of the reticuloendothelial system, concentrated mainly in the spleen, liver, bone marrow, and lymph glands, with the spleen being assigned the primary role, since microscopy reveals, for example, in the cells lining the sinuses and in the reticulum, phagocytosed erythrocytes and products of their disintegration. These pictures are extremely rare in the liver and bone marrow, on the basis of which it should be thought that under normal conditions the participation of the latter in E. is extremely limited. An exception is represented, for example, by geese, ducks, pigeons, in which, due to the underdevelopment of the spleen, E. is concentrated mainly in the liver (Mc Nee). Among the lymph glands, E. occurs in the so-called hemolytic glands, while ordinary nodes do not participate in E. However, this opinion is hardly correct, since there are indications, for example, on the glands of the portal ring, which as the function of the spleen fades with age and especially under pathological conditions (Biermer's anemia) possess considerable E. (Fahr). Under pathological conditions, for example, in hemolytic anemias, in Banti's disease, in typhoid fever in newborns, in poisoning with small doses of hemolytic poisons (AsH₃, toluenediamine, phenylhydrazine, etc.), E. is significantly strengthened not only in the mentioned organs but also appears in the parenchymal cells of the liver, in the kidneys, in the pancreas, in the skin, in the stomach, and directly in the bloodstream. Systematic studies of the blood after removal of the spleen in rats, white mice, and guinea pigs reveal E. mainly in monocytes, partially also in neutrophilic leukocytes. In monocytes, not only erythrocytes but also all phases of their destruction are found. Individual cells containing 4-5 erythrocytes are encountered (Hirschfeld, Sumi). It is possible that these erythrophages also arise in the reticuloendothelial system, as for example is observed in Biermer's anemia (Schilling). After injection of vaccine of Bacillus proteus, cells stuffed with erythrocytes also appear in the blood, and all phases of their destruction up to the appearance of hemosiderin. At the same time, hyperplasia of the reticuloendothelium of the spleen and liver occurs. Also under these conditions, E. is strengthened after splenectomy (Dickmann). Removal of the spleen causes vicarious E. and deposition of iron also in the Kupffer cells of the liver, in the bone marrow, in the lymph glands. For example, in splenectomized rats and mice, significant enhancement of E. was found in Kupffer cells (M. Schmidt, Lepehne, Nishikawa and Takagi). Phagocytosed erythrocytes undergo a series of changes: they lose Hb, disintegrate into separate clumps, turn into colorless formations or shadows, and finally disappear completely. The chemical transformations of Hb lead to the appearance in the cells of an iron-containing pigment—hemosiderin. The process of phagocytosis of erythrocytes is preceded by various processes of disintegration of their lipoprotein structure (see Hemolysis). As a result, agglutination of them or disintegration into separate clumps occurs, and in places of slowed blood flow, for example in the sinuses of the spleen, their adhesion to endothelial and reticular cells with subsequent phagocytosis. Furthermore, the possibility of phagocytosis of undamaged erythrocytes is assumed, but this is not recognized by all. For example, it is assumed that the main method of their destruction is fragmentation in the bloodstream with subsequent phagocytosis of the resulting clumps (Rous, Doan, etc.). Furthermore, as a constant inclusion in normal blood, the so-called colorless spheres, which form from erythrocytes through their loss of Hb, are described (Fohreus). Thus, there are three viewpoints on the processes preceding E.: one allows for the possibility of phagocytosis of whole, undamaged erythrocytes, another considers that the destruction of erythrocytes begins outside the cells and only ends in them, and the third considers the entire complex process of destruction of erythrocytes as extracellular. On the basis of the various literary data pertaining to this, it should be recognized that E. is only one of the occurring types of destruction of erythrocytes. For example, in experiments with the action on erythrocytes of various chemical agents (HCl, alkalis, bile, NaCl), on the cinematographic film, the most diverse types of decolorization, rupture, and fragmentation of erythrocytes are shown. These facts demonstrate the considerable diversity of types of destruction of erythrocytes, appearing with only variation in the external environment (Comandon and P. de Fontaine). If to this is added the significance of the species of animal (Mc Nee) and the functional state of the reticuloendothelial system in each individual case, then the diversity of conditions on which the type of destruction and the processes preceding phagocytosis of erythrocytes depend becomes understandable.