Figure 1. Exogenous histones increase the number of platelet-ultra-large von Willebrand factor (ULVWF) strings (arrows) during parallel-plate flow (700 s-1).(A) Phase contrast images of lyophilized platelet-ULVWF strings over HUVEC stimulated with various agonists.(B and C) Merged differential interference contrast and fluorescence image of ULVWF strings after labeling with an FITC-conjugated anti-VWF antibody in the presence (B) and absence (C) of platelets. Note the co-localization between platelet strings and VWF in (B).(D) Stimulation of HUVEC with calf thymus histone (CTH) or histone H4 significantly increased the number of platelet-ULVWF strings. Scale bar= 20 μm. N= 3-7 experiments per group.* P< 0.05,** P< 0.01,