Dengue induces shedding of IL-1β–rich microparticles in platelets. (A) The proportion of MPs per 100 platelets was assessed in samples from healthy subjects (control) or dengue-infected patients (dengue). (B) The percentage of IL-1β–positive MPs in samples obtained from control participants or dengue patients. The boxes indicate the median and interquartile ranges and the whiskers indicate 5 to 95 percentile. (C-D) Washed platelets from healthy volunteers were exposed to mock, infective DV-2 (DV), or heat-inactivated DV-2 (heat DV) as described in Patients and methods. (C) The levels of platelet-derived MPs and (D) the percentage of IL-1β–containing MPs for each condition are shown. The bars represent mean ± SEM of 8 experiments performed using samples from independent healthy donors. *P < .05 and **P < .01 compared with healthy volunteers or mock exposed platelets. (Insets) Representative density plots showing (B) IL-1β–expressing MPs from 1 healthy volunteer and 1 dengue patient or (D) platelets from 1 healthy volunteer that were exposed to mock, DV, or heat DV. The values in each region of the quadrants indicate the cell frequencies in the respective quadrant.