Effect of Antibody Binding and Agglutination on Human Platelet Glycolysis: Comparison with Thrombin and Epinephrine

Freshly collected human platelets were washed in a modified human Ringer solution, pH 7.1, and aerobically incubated in the same media for 1 hour in the presence or absence of glucose. The effect of rabbit antihuman platelet antibody or univalent rabbit antihuman platelet antibody fragments (Fab) on platelet glycolysis was determined. Although ATP expenditure and glycogenolytic depletion were noted following platelet agglutination by antibody, these changes were not considered to be of major importance in the in vivo destruction of platelets. Univalent fragments were shown to bind to platelets without causing platelet agglutination or any detectable change in the glycolytic parameters. In contrast, intact platelet antibody resulted in platelet agglutination which was associated with an increase in lactate production and a decrease in ATP levels when platelets were incubated in the absence of glucose. Glucose-6-P levels did not change. When platelets were incubated in the presence of glucose, glucose uptake increased, ATP levels declined and glucose-6-P levels were unchanged. However, the increased glucose uptake was not accompanied by a parallel increase in lactate production as in the case with thrombin or epinephrine-induced agglutination of platelets. It is postulated that platelet antibody activates a glucose-requiring nonglycolytic pathway, perhaps the hexosemonophosphate shunt or the Krebs’ cycle.