The effect of LPS and TNF- on vWF antigen in murine plasma. Mice were injected intraperitoneally with endotoxin (50 μg; A) or TNF- (4 μg; B). At various times, plasma was collected from individual mice and the concentration of vWF antigen was determined as described in Materials and Methods. The results are expressed as the mean percentage of vWF antigen detected, with the standard deviation for results from at least 3 different mice indicated by the error bars. The concentration of vWF in the plasma of mice treated for 8, 16, or 24 hours with either LPS or TNF was significantly higher than that in the plasma from untreated controls (P < .001).