Endothelial cell activation and vaso-occlusion after anti-CD40 injection. Mice were treated with anti-CD40 antibody and euthanized 30 hours postinjection. (A) messenger RNA (mRNA) expression of Vcam-1 measured by real-time polymerase chain reaction (RT-PCR) in fluorescence-activated cell sorting (FACS)-sorted CD45^low CD31/CD102^high liver endothelial cells of saline (control) (n = 3) and anti-CD40–treated (n = 4) wild-type mice. (B) Left panel, VCAM1 quantification in plasma of saline (n = 5) and anti-CD40–treated (n = 5) mice. Right panel, ICAM1 quantification in plasma of saline (n = 4) and anti-CD40–treated (n = 6) mice. (C) Representative photograph of a H&E-stained liver tissue section from an anti-CD40–treated mouse. (D) Representative photograph of a H&E-stained splenic tissue section from an anti-CD40–treated mouse. (E) Macroscopic image of representative lungs of saline (top left panel) and anti-CD40–treated mice (bottom left panel). Ischemic infarcts can be detected in the anti-CD40–treated mouse lungs (dark spots on the lungs). Representative photographs of H&E-stained lung tissue sections from control (top middle panel) and anti-CD40–treated mice (bottom middle panel). A higher magnification of an intravascular thrombus from the lung section of the anti-CD40-treated mouse is appreciable in the top right panel. (F) Plasma ALT concentrations in CD40^flox/flox mice (wild-type) (black dots) or VE-cadCre CD40^flox/flox mice (red dots) after saline (n = 2-3) or anti-CD40 antibody treatment (n = 4). Individual symbols represent 1 mouse; ****P < .0001, *** P < .001, not significant (n.s.) P > .05, for all panels.