Jeannine, I've just looked back through my mails at the original summary (if you want a copy let me know and I'll forward it). The original post was about using ionophore for platelet activation in an assay for HIT antibodies, but seemed to spread its remit a bit further. Aaron Tomer made the strongest recommendation for using annexin V binding over P-selectin (CD62P) in this assay. The trouble is with platelets it depends what you are looking for. In HIT annexin V binding is probably better because the pathogenesis of the disease involves "strong" activation responses mediated by FcRII. However, if you wish to look at "weaker" responses where only alpha granules contents are released you may wish to use antibodies to P-selectin. A caveat on this is that several researchers have shown that platelets can degranulate and shed P-selectin. So if you are using samples that were taken sometime ago, you may not observe elevated levels of P-selectin where expected. After that it all comes down to what these observations mean in vivo, and I don't even want to start on that debate. It is perhaps enough to say the more we understand, the less we know. Sorry this hasn't really given you a definite answer for which is the better marker, but they all have there merits. Regards Craig PS Don't forget there are other methods for looking at platelet activation/function eg ELISA for chemokines. ---------- From: jsn9@imap.pitt.edu To: cyto-inbox Subject: Platelet Activation Marker: CD62P vs An Date: Thursday, March 21, 2002 9:42PM Hello all! A couple of months ago there was a posting about platelet activation, and it was mentioned that Annexin V binding is a better marker of platelet activation than is CD62P expression. Can anyone confirm this, and if this is true, why is Annexin V better? Thanks for your help! Jeannine Navratil Center for Analytic Cytometry University of Pittsburgh Arthritis Institute
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