A reliable plasma marker of platelet activation: does it exist?

Despite the clear importance of the platelet in various conditions and diseases, there are few opportunities to assess the physiological and pathological functions of this cell. Those without access to a flow cytometer or platelet aggregometer rely on secreted or release products of the platelet. Principle among these molecules are alpha granule components beta thromboglobulin and platelet factor four, and membrane constituents such as P selectin, gpV and glycocalicin. However, notwithstanding the ease of measurement of these markers (i.e., by ELISA) each one has its own particular disadvantage, mostly of methodology and specificity. Nevertheless, if our goal is to improve our ability to recognize and treat subjects with thrombotic disorders, then additional studies on these molecules may prove to be a sound investment. Copyright 2002 Wiley-Liss, Inc.