[The novel in vivo platelet activation marker, soluble CLEC-2].

Unlike for anticoagulants, no good monitoring methods exist for antiplatelet agents, and their monitoring is considered unnecessary. In the platelet aggregation test, which is the standard test for platelet function, aggregation is evaluated by adding a platelet activator to platelets in a cuvette. Therefore, it provides information on the maximum potential of platelets to induce aggregation, but not the actual in vivo degree of platelet activation. In vivo platelet activation markers are not widely used because they require a special blood collection method, although some tests are covered by insurance. My colleagues and I identified the platelet activation receptor C-type lectin-like receptor 2 (CLEC-2) and found that CLEC-2 is cleaved and released during platelet activation. We established a plasma-soluble CLEC-2 (sCLEC-2) assay system with the aim of using it as a marker of in vivo platelet activation. Elevation of sCLEC-2 has been reported in various thrombotic diseases. The multi-center prospective cohort study CLECSTRO is now underway to investigate the usefulness of sCLEC-2 for diagnosis, typing, and prognostic estimation in acute ischemic stroke.