Adenovirus induces platelet-leukocyte aggregate formation and both platelet and leukocyte MPs following intravenous administration to mice. (A) Whole blood samples obtained from Balb/c mice during the first 24 hours following injection of adenovirus. Flow cytometry assessment of platelet-leukocyte aggregate was performed as follows: platelets were first gated based on the CD41 marker and the percentage of CD45⁺ cells (leukocytes) associated with platelets was assessed on another histogram. The upper right quadrants of the histograms show an evolving significant increase in platelet-leukocyte aggregates from before to various time points following adenovirus treatment. These data are representative of 3 independent in vivo experiments. (B) Graphs showing the average number of MPs in plasma obtained from Balb/c mice based on separate assessment of CD41 and CD61 (PMPs) and CD45 (LMPs). There is a significant increase in PMPs (n = 3, P = .02 based on CD41; P < .001 based on CD61 marker) and LMPs (n = 3, P = .03) at 2 hours following virus administration compared to the preinjection levels (Before). Values shown are the mean ± SEM.