Quantitative immunoblotting of purified VWF substrate degraded by ADAMTS-13 in plasma dilutions. Lanes 1-7 = assay calibration by normal plasma dilutions of 1:20 (100% activity), 1:40 (50%), 1:80 (25%), 1:160 (12.5%), 1:320 (6.25%), 1:640 (3%), and buffer (0%). Lanes 8-12 = plasma dilutions (1:20) of the proposita and her parents. Lane 8 = father (∼50% activity), lane 9 = mother (∼50%), lanes 10-12 = proposita (lane 10 = March 13, 2003, before plasma infusion, < 3%; lane 11 = March 27, 2003, before plasma infusion, < 3%; lane 12 = March 27, 2003, 2 hours after plasma infusion, ∼8%).