Flow cytometric analysis (contour plot) of platelets and platelet-derived microparticles in a patient with acute myelogenous leukemia (A) and a normal individual (B) using anti-CD61 and anti-CD42b antibodies. Whole blood was treated with platelet-specific fluorescent antibodies as described previously.5CD61⁺/CD42b⁺ events (n = 50,000), representing platelets and platelet-derived microparticles, were gated and are shown in forward and side scatter mode. Normal-size platelets (>2 fL) and platelet-derived microparticles (<2 fL) were defined as shown in the graph by a size-threshold of 2 fL, established with the help of fluorescent calibration beads.