Acquisition and interpretation of flow cytometric data. (A) Representative histogram showing binding of the C3 antibody (thin line) to 25% of the platelet population. M1 was determined by subtraction of the background fluorescence (thick line). Background signal from the control antibody was given an M1-value of approximately 1% in all experiments. (B) The PMP gate (R1) was determined in FSC and SSC by 0.8- to 1-μm fluorescent beads in buffer. (C) PMPs in the R1 gate were calculated in relation to the R2 gate consisting of 6μm non-fluorescent beads. Detection of events was terminated when 10 000 counts were obtained in the R2 gate. (D) Detection of phosphatidylserine-positive PMPs by annexin V:PE-Cy5 labeling in FL3 (y-axis) in relation to SSC (x-axis).