Triplet-free platelets are more aggregative and remarkably so on adding ADP
Aggregation of platelets in suspension was monitored in terms of reduction in the absorbance of the suspension at 405 nm. Native (non-denuded) platelets were little aggregated upon addition of ADP regardless of their pre-treatment with jacalin. Triplet-free (denuded) platelets that were more prone to aggregation than their native counterparts even before ADP addition, aggregated substantially more upon addition of ADP (Fig.6). However, pre-treatment of denuded triplets with jacalin offered near complete protection from ADP-mediated aggregation. The primary event in ADP-mediated platelet aggregation is binding to the two G-protein-coupled receptors P2Y1 and P2Y12 on platelet surface [24]. Though no data on O-glycan dependence of this binding was available, involvement of GPIIb/IIIa in subsequent events in ADP-mediated aggregation has been reported [20]. Besides explaining the jacalin-mediated inhibition of  ADP-induced aggregation of denuded platelets, results in Fig.6 also suggested the possibility that GPIIb/IIIa that gets exposed following denudation was a triplet reeptor.