Western blot of the multimeric pattern of vWF R834Q after incubation with plasma from patients suffering from classic TTP. C1, plasma from a healthy donor incubated with vWF R834Q. C2, plasma from a healthy donor incubated with vWF R834Q in the presence of EDTA (1 mmol/L). Lanes 1 through 5, patient plasmas (numbers as in Table 1).