Effect of the molecular weight of HA on histone-induced cytotoxicity and platelet aggregation. (A) HL-60 cells were incubated with CTH (50 µg/mL) at 37°C for 30 minutes in the presence or absence of 100 µg/mL HA with a molecular weight of 150, 500, or 1000 kDa. Cell damage was measured by PI staining and flow cytometry. (B) Platelet aggregation was measured after 20 µg/mL H4 was added to washed platelets in the presence or absence of 100 µg/mL of HA at 150, 500, or 1000 kDa. Data are presented as mean ± SEM of 3 independent experiments using one-way ANOVA with Bonferroni’s multicomparison test. ***P < .001, **P < .01, *P < .05 compared with (A) histone or (B) H4 challenge groups.