Fig. 5

Human platelet activation by cat K. Side and forward scatters of plasma rich in platelets (PRP) from different blood donors prepared under the same conditions. PRP were stained with lineage markers: CD61-FITC (platelets) and Annexin V-PE (phosphatidyserine exposure) or the appropriate isotype controls. PRP was analyzed by flow cytometry. Platelets were treated with apyrase (5.0 UNIH/mL). The areas Q1 and Q2 correspond to nonactivated and activated platelets, respectively. (a) Forward - by sidescatter profiles of events in PRP. Populations identified by futher gating. CD61+ nonactivated platelets. Representative histogram of CD61+ platelet resident in PRP. (b) α-thrombin (0.001UNIH/mL), (c) Platelets activated by cat K (20 nM), (d) cat B (0.2 µM), and (e) papain (1.6 µM), and their corresponding histograms. Note the increased number of events in Q2 after stimulation with cat K, papain, and α-thrombin. Flow cytometric quantification of Annexin V-PE (beads were used for size calibration). Each figure represents an analysis of 10,000 events with SSC (side scatter) on the abscissa, and FITC fluorescence intensities on the ordinate. (f) The bar graph shows percentages of Annexin-V-PE. Data are expressed as mean ± SEM from 3 independent experiments (*p<0.05). See also Fig. 1 and 3