Characterization of multiple platelet activation pathways in patients with bleeding as a high-throughput screening option: use of 96-well Optimul assay

Up to 1% of the general population have mild bleeding disorders, but these are often poorly characterized, particularly with regard to the roles of platelets. Here we have compared the usefulness of Optimul, a 96-well-plate-based assay of seven distinct pathways of platelet activation, to characterize inherited platelet defects in comparison to light transmission aggregometry (LTA). Using Optimul and LTA, concentration-response curves were generated for arachidonic acid, ADP, collagen, epinephrine, TRAP-6, U46619, and ristocetin in samples from (i) healthy volunteers (n=50), (ii) healthy volunteers treated with antiplatelet agents in vitro (n=10), and (iii) patients with bleeding of unknown origin (n=65). The assays gave concordant results in 82% of cases (κ=0.62, p