Platelet interaction with bacteria. I. Reaction phases and effects of inhibitors

Interactions between human platelets and several common species of bacteria have been studied in vitro by the technic of recording nephelometry. Results of this investigation have established the following parameters of platelet-bacterial interaction: (1) Bacteria are potent stimuli of the platelet-aggregating reaction. (2) The platelet-bacterial interaction proceeds through four distinct phases which are separable by varying the platelet-bacterial ratios or adding appropriate chemical inhibitors. (3) The degree and rate of the platelet response is proportional to the ratio of bacteria to platelets. (4) Direct contact between platelets and bacteria, physiologic levels of divalent cations and nucleotide release from platelets are essential for aggregation of platelets by bacteria. (5) By adding equivalent numbers of six species of microorganisms to platelet-rich plasma, their potency as initiators of the platelet reaction was determined, with Staphylococcus being the most powerful.