Fig. 1. Changes of plasma levels of ADAMTS13 activity (:AC), ADAMTS13 inhibitor (:INH) and platelet counts in 20 well ADAMTS13:AC-responder (left) and 32 poor ADAMTS13:AC-responder to PE (right).

In the figures, the shaded areas show normal ranges, and the vertical bars indicate values of mean ± SD.

In well ADAMTS13:AC-responders (left), plasma levels of ADAMTS13:AC increased to 15.0 ± 10.9% on 3^rd PE day and then did not decrease below 10% within 14 days after PE initiation. Plasma ADAMTS13:INH titers decreased on 4^th PE day, and then restored to almost pre-PE levels on 10^th PE day, followed by a consistent decrease to the undetectable level on 14^th PE day. Platelet counts increased to normal level on 6^th PE day, followed by a slight dip, and then re-increased to normal on 14^th PE day.

In poor ADAMTS13:AC-responders (right), plasma levels of ADAMTS13:AC never increased to more than 10% during 14 days after PE initiation. Further, plasma ADAMTS13:INH titer decreased from 5.9 ± 4.5 BU/ml before PE initiation to 1.4 ± 0.7 BU/ml on 4^th PE day, and then remarkably increased to 14.8 ± 0.7 BU/ml on 10^th PE day, termed ‘inhibitor boosting’, followed by a slow decrease to undetectable level over one-month after PE initiation. A recovery of platelet counts was very slow, and the count reached to more than 150×10⁹ /L on 22^nd PE day.