DENV NS1 activates platelets. (A) Gating strategy for analysis of P-selectin (CD62P) expression on CD41⁺ platelets. (B) Platelets from healthy donors were incubated with 0, 0.5, 5, and 50 μg/mL of NS1 for 1.5 or 3 hours. (C-D) Platelets were stimulated with 50 μg/mL of NS1 (C) or 10 μg/mL of LPS (D) for 3 hours in the presence of 0, 10, 50, or 100 μg/mL polymyxin B. Bars represent mean ± standard error of the mean of 5 independent experiments. *P < .05, compared with unstimulated platelets in the same time frame; #P < .05 between platelets treated or not with polymyxin B.