Evidence for two mechanisms of human erythrocyte endocytosis by Entamoeba histolytica-like amoebae (Laredo strain).

A study of the ultrastructural aspects of endocytosis of human erythrocytes by Entamoeba histolytica-like amoebae (Laredo) revealed two different mechanisms of endocytosis. First, there is classical phagocytosis which consists of the formation of a phagocytotic pseudopod. This process begins with the engulfment of the red blood cell followed by its entrapment in a food vacuole of the same size as the erythrocyte. It is then digested in the food vacuole. The second means of endocytosis is achieved through a preliminary lytic attack on the red blood cell. Following attachment of the prey to the attacking cell, dendritic extensions elongate from the surface of the amoeba at the site of attachment. Intense folding and liquefaction of the red blood cell membrane is then observed. The fluid membrane is then sucked into the amoeba through a pinocytotic-like channel. The end result is the formation of small vacuoles in the amoeba's cytoplasm, filled with the digested red blood cell.