Platelet enhancement of postphagocytic destruction of Listeria monocytogenes in cultured mouse peritoneal macrophages

Abstract

Although platelets are principally known for their critical role in hemostasis, a considerable amount of recent literature suggests that they function as an integral factor in host defense against infectious disease. For example, the primary source of β lysin, a heat stable complement independent bactericidal system, is the platelet which undergoes aggregation and degranulation during the clotting process. Heat stable antibacterial activity of rabbit serum is platelet dependent and resides preformed within platelets as a cationic protein constituent of lysosomal granules. Clawson and White have demonstrated that when several common bacterial species are added to platelets in their native plasma, a series of reactions occurs that terminates in the irreversible aggregation of the platelets with sequestration of the bacteria within the aggregates. Because the sequestered bacteria retained viability, it is suggested that under normal conditions, the clumping reaction assists in the physical removal of microorganisms by the RES. Rabbit platelets enhance the bactericidal capability of cultured mouse peritoneal macrophages against Listeria.