Characterization of circulating microparticles (MPs) is usually performed by flow cytometry. Annexin V, a protein that Ca(2+)-dependently binds to phosphatidylserine, has been used to define entire microparticle (MP) populations, but not all MPs bind AnxV. Recent reports have correlated AnxV negative MPs to clinical parameters in systemic diseases, which emphasize the importance of including characterization of AnxV-binding. An obstacle in flow cytometric analysis of AnxV-binding to MPs is that plasma may clot when adding the Ca(2+)-containing buffers. We here devise a simple method for comprehensive assessment of circulating MPs directly from platelet-poor plasma with characterization of AnxV-binding and of cellular origin of MPs.
Journal of Immunological Methods, 2013, Vol 388, Issue 1-2, p. 49-59