Expression of platelet P-selectin (CD62p) in vitro and following intravenous administration of adenovirus to mice. (A) Murine washed platelets were incubated with adenovirus for 30 minutes at 37°C and analyzed for CD62p by flow cytometry. The index of platelet activation IPA⁺ (MCF × percentage of CD62⁺ events) is significantly increased in adenovirus (Ad)–treated platelets compared to resting platelets (average of 5 experiment). Thrombin-activated platelets are tested as a positive control. (B) Flow cytometry histogram representative of 5 in vitro experiments showing increased fluorescence in adenovirus-treated platelets and thrombin-activated platelets compared to resting platelets and the isotype control. (C) Platelet P-selectin expression during the first 24 hours following adenovirus or LPS intravenous administration in mice. Graph represents fold increase of percent of P-selectin positive platelets after adenovirus compared to preinjection levels. Significant P-selectin expression is significant in both LPS and adenovirus treated at 1 hour compared to the preinjection level (adenovirus-treated mice n = 4, P < .001). Values are the mean ± SEM.