Major basic protein on EETs activates platelets. (A) Eosinophils activated in vitro by platelets (red) formed EETs containing MBP (green) and DNA (white, DAPI). On EETs, MBP and platelets colocalize (arrows) as shown in higher magnification in the insets at the top of the panel. Images from confocal microscopy representative of 3 experiments. (B) Thrombus formation in MBP^−/− mice (n = 8) is significantly impaired compared with thrombus formation in MBP^+/+ littermates (n = 10). (C) Representative images of platelet aggregation (gray area, dotted line) in the carotid artery (white lines) of MBP^−/− and normal thrombus development in MBP^+/+ mice 20 minutes after endothelial injury. (Recanalization is marked by dotted line). (D) EPX^−/− mice (n = 8) as well as EPX^+/+ (n = 10) mice showed occlusive thrombus formation. (E) APC concentrations in plasma of MBP^+/+ (n = 5) and MBP^−/− (n = 8) did not show any differences after arterial thrombosis. (F) Platelet aggregation induced by ADP in IL-5 and eotaxin-treated whole blood of female MBP^−/− mice (n = 4) was significantly decreased compared with that in wild-type mice (n = 3). For panels B and D-F, data are mean ± SD. ***P < .001.