Depletion of Tregs does not induce a general defect in platelet function or activation. (A) Platelets in whole blood from Treg-depleted DEREG mice (DEREG + DT) form stable thrombi when perfused over a collagen-coated surface at a shear rate of 1000/s. On the left are representative phase-contrast images. On the right is the mean surface coverage by thrombi in the indicated mouse groups. DT indicates diphtheria toxin; and ns, not significant. (B) In vivo analysis of thrombus formation in Treg-depleted DEREG mice (DEREG + DT) and controls. Mesenteric arterioles were treated with FeCl3 and adhesion and thrombus formation of fluorescently labeled platelets were monitored by in vivo fluorescence microscopy. Representative images (left) and the time to vessel occlusion (right) are shown. Each symbol represents one individual. ns indicates not significant. Data are presented as means ± SD or scatter plots showing the median (panel B).