Phagocytosis is a nonspecific defense mechanism in which various phagocytes engulf and destroy the microorganisms of disease.
Phagocytes. Among the important phagocytes are the circulating white blood cells called neutrophils and monocytes. In the tissues, the monocytes are transformed into phagocytic cells called macrophages. The macrophages move through the tissues of the body performing phagocytosis and destroying parasites. They are part of thereticuloendothelial system. Phagocytes also initiate the processes of the immune system.
The process of phagocytosis begins with attachment and ingestion of microbial particles (Figure 1 ) into a bubblelike organelle called a phagosome. Once inside the phagocyte, the phagosome containing the microorganism joins with a lysosome, which contributes enzymes. The fusion of phagosome and lysosome results in aphagolysosome. Microorganisms are destroyed within minutes, and the microbial debris is eliminated from the cell in the process of egestion. In the immune process, chemical portions of the microorganism called antigenic determinants are displayed on the surface of the phagocyte to stimulate the immune process.