mAbs induce platelet signaling via crosslinking platelets. (A) Percentage aggregation of human PRP treated with AK2, IgG, 6B4 Fab, SZ2 + EDTA, 6B4, SZ2, or ristocetin, determined via aggregometry. (B) Representative images of platelets (right: bright field, left: anti-CD41) in PRP treated with 6B4 at low shear. Images obtained via imaging flow cytometry. Arrows indicate the aspect ratio that corresponds to each set of images. Vertical dotted line demarcates the gate used to identify crosslinked events. Scale bar = 10 μm. (C) Frequency of crosslinked events (events with aspect ratio <0.8) in PRP treated with IgG, AK2, or 6B4 at static (0 dyn/cm2) or sheared (30 dyn/cm2) conditions (n = 3). (D) Contour plots of forward scatter (FSC-A) vs anti-mouse antibody fluorescence for platelet-mimetic beads treated with AK2 (red), 6B4 (blue), and IgG (gray) under sheared conditions. Contour lines = 5%. **P < .01, ***P < .001.
