Platelet-endotoxin interaction: a review.

The studies reviewed in the present manuscript outline the effects of bacterial endotoxins on human and animal platelets. In animals the endotoxin administration is followed by thrombocytopenia, presence of platelet aggregates in the blood vessels of several organs, appearance of appreciable quantities of serotonin in plasma and increased platelet factor 3 availability. These in vivo effects can readily be explained by the in vitro demonstration that endotoxin aggregates platelets, induces release of vasoactive amines and adenine nucleotides and activates platelet factor 3. There is substantial evidence suggesting that the mechanism of this animal platelet-endotoxin interaction is immunological and complement dependent. In humans thrombocytopenia is frequently observed in endotoxemia as encountered during Gram-negative sepsis indicating that platelets are involved in some of the biological effects endotoxin. In vitro experiments demonstrate that several endotoxin preparations significantly enhance a weak procoagulant activity of human platelets different from platelet factor 3.