Fig. 1.
Chromatographic purification of von Willebrand factor–cleaving protease.
Eight batches of 100 mL normal human plasma each were first fractionated by immunoaffinity chromatography on the anti–vWF-cp autoantibody–containing IgG fraction from a patient with acquired TTP. Elution fractions collected under the last column of each step were counted from the start of each step. The fractions containing vWF-cp activity were pooled and further subjected to chromatography, as indicated schematically.represents fraction with vWF-cp activity.