LR04 does not affect tail bleeding time but protects mice in an MV-induced pulmonary thrombosis model. (A) Tail bleeding times of mice injected with LR04 (n = 8) or an isotype control antibody (n = 6), 25 µg/mL of estimated total blood volume. Columns represent mean ± SEM. (B) Representative microscopic fluorescent image of lung sections of mice injected with a mixture containing epinephrine (60 ng/g bw) and fluorescently labeled HPAF-MVs (0.1 µg/g bw). Nuclei were stained with 4′,6-diamidino-2-phenylindole (blue) and platelets with an anti-CD41 antibody (red), injected labeled MVs (green) (20× magnification). Arrows indicate thrombi (fibrin = bright pink). Kaplan-Meier survival curves of mice intravenously injected with a mixture containing epinephrine (60 ng/g bw) and HPAF-MVs (0.1 µg/g bw) (n = 22 per group) (C) or epinephrine (60 ng/g bw) and collagen (3 µg/g bw) (n = 5 per group) (D). The mixture was preincubated with LR04 or an isotype control antibody, 25 µg/mL of estimated total blood volume. Mice were observed for a maximum duration of 30 minutes. ***P < .005, log-rank (Mantel-Cox) test. (E) Representative microscopic images of picro-Mallory–stained lung sections of mice, which were injected with a mixture of epinephrine (60 ng/g bw) and HPAF-MVs (0.1 µg/g bw).The mixture was preincubated either with 25 µg/mL estimated blood volume (2.25 µg/g bw) of LR04 or isotype control antibody. 5× magnification and 20× magnification (top left), arrows indicate fibrin deposits. (F) Numbers of thrombi per visual field, counted at 10× magnification (n = 15 per group). Columns represent mean ± SEM. *P < .05, Mann-Whitney U test. (G) Summary cartoon (details are provided in the text). n.s., not significant.