Platelets in Bacterial Infections

Publisher Summary This chapter focuses on the interaction of human platelets with bacterial pathogens and the potential that this interaction has for being a detriment or a benefit to the host. Platelets have three general characteristics that have led to their identification as a host defense cell and being likened to a special form of leucocyte. These characteristics are their propensity to interact with pathogenic organisms, their content of lysosomal products that are released on stimulation, and their metabolic products that contribute to the pool of inflammatory mediators. Since platelets normally reside exclusively in the blood circulatory system, their initial and principal contribution as a host defense cell is likely to be their interactions with particulates in the blood stream—including non-biologic materials, antigen-antibody complexes, viruses, bacteria, or other micro-organisms. It has been pointed out that in its simplest form platelet-bacterial interaction is viewed as a special form of platelet interaction with non-biological particulates. The involvement of platelets in the clearance process appears to alter both the rate and organ distribution of particle deposition. Numerous examples of clinical disorders have been presented in which platelet-bacterial interaction may be reasonably implicated in the pathogenesis of the disease. These aid in underscoring the significance of in vitro and in vivo studies of platelet-bacterial interaction to human disease. This discussion of the interactions of platelets with bacteria has emphasized that the phenomenon has potential for both beneficial and harmful outcomes for the host.