Comparison of ADAMTS13 activity in 2 mouse strains. (A) SDS-PAGE and immunoblotting depicting VWF proteolytic fragments (176-kDa and 140-kDa fragment dimmers) generated from cleavage of exogenous VWF multimers by ADAMTS13 in a normal human plasma, a FVB/NJ plasma, and a C57BL/6J plasma. VWF multimers were incubated with each plasma sample at the indicated dilution in the presence or absence of EDTA. The increased optic density in the absence of EDTA represents the product of proteolysis. (B) A plotting of the level of the 176-kDa fragment dimer against the plasma concentration. At each dilution, the FVB/NJ plasma was more active than the normal human plasma or the C57BL/6J plasma in generating the proteolytic fragment. (C) A dot plot of the ADAMTS13 activity levels in 18 FVB/NJ and 18 C57BL/6J mice. The mean and standard deviation are also shown for each group (P < .001).