Effect of vWf deficiency on P-selectin expression.

(A) Leukocyte rolling in LDLR-deficient mice on an atherogenic diet. Four-week-old LDLR−/−vWf+/+ and LDLR−/−vWf−/− mice were fed either normal mouse chow (white bars) or atherogenic diet (black bars) for 4 weeks. Animals were injected with 6 g rhodamine, and the mesenteric venules were exposed. The number of leukocytes was quantified by counting the number of cells passing through a perpendicular plane per minute. The atherogenic diet significantly increased rolling in both LDLR−/−vWf+/+ (P = .03) and LDLR−/−vWf−/− (P = .0004) mice (n = 6-9). The number of rolling leukocytes was comparable in the 2 genotypes of mice on atherogenic diet (P = .1). (B) Immunohistochemical staining of the aortic sinus with an anti–P-selectin antibody. Sections were obtained from mice that were on an atherogenic diet for 4 weeks and were stained with a polyclonal antibody against P-selectin. Staining for P-selectin was weaker in mice lacking vWf. Immunohistochemical staining with a PECAM-specific antibody confirmed the integrity of the endothelial monolayer (not shown). Bar = 100 μm.