Effects of Listeria monocytogenes Hemolysin on Phagocytic Cells and Lysosomes.

The effects of Listeria monocytogenes hemolysin on lysosomes and phagocytic cells were investigated. Hemolysin caused release of beta-glucuronidase and acid phosphatase from suspensions of rabbit and rat lysosomes prepared from liver homogenates. The degree of lysis was proportional to the concentration of hemolysin added. There appeared to be no significant difference between the sensitivities of rat and rabbit lysosomes to disruption. Studies on the effect of pH and temperature on lytic activity suggested that hemolysin could function under conditions which might exist within phagocytic cells. Peritoneal exudates from rabbits and mice were exposed to hemolysin and observed by phase microscopy. Hemolysin possessed leucocidal activity and caused degranulation of both rabbit and mouse cells. Optimal activity against lysosomes and peritoneal exudate cells required activation of hemolysin with a reducing agent and could be prevented if hemolysin was previously incubated with cholesterol.