Lectin-induced adhesion of human platelets to glass. Comparison with the lectin-induced aggregation

Effects of Phytohaemagglutinin (PHA), Concanavalin A (Con A) and Lens culinaris (Lens) lectins on the adhesion of human platelets to glass surface were studied. All the three lectins tested enhanced platelet adhesion to glass. Concentration-effect curves showed that maximum effect was reached at about 25-30 micrograms/ml. In the presence of autologous plasma both spontaneous and lectin-induced adhesion to glass were diminished. The inhibitory effect of KCN, NaN3, cytochalasin B and partly of colchicin suggests that lectin-induced platelet adhesion to glass is a process depending on cell metabolism and the state of the cytoskeleton. Only PHA was observed to be a potent inducer of platelet aggregation similar to physiological aggregants. Con A had no effect on platelet aggregation but caused shape change which was blocked by metabolic inhibitors. Neither shape change nor aggregation were induced by Lens up to a concentration of 400 micrograms/ml. A comparison between the mechanisms of lectin-induced substrate adhesion and lectin-induced aggregation of platelets is described.