Figure 2

Results of the in-house ELISA for the detection of anti-VWF-IgG and multimer analysis. (A) Immobilized recombinant human VWF derived from CHO cells was used to measure IgG autoantibodies to VWF. The titer was 2.6 OD at presentation (day 0) and decreased to 0.8 OD during effective prednisolone therapy (day 31). A steep decline in VWF on day 38 following reduction of the daily prednisolone dose to 20 mg a week earlier was accompanied by a temporary increase in the anti-VWF-IgG titer to 1.2 OD on day 45. After six months of follow-up, the titer had decreased to 0.6 OD, but was still above the reference range of the ELISA as indicated by the shaded red area. (B) Before the initiation of prednisolone, presence of unusually large VWF plasma multimers (arrows) and absence of typical VWF triplets (arrow heads) indicated decreased proteolysis of newly released, but rapidly cleared VWF (day 3). The multimeric pattern normalized during effective immunosuppressive therapy with prednisolone (day 24). A high-resolution 1.6% agarose gel (left four lanes) and a low-resolution 1.2% agarose gel (right two lanes), which allows for better migration of the larger multimers into the gel, are shown. Different dilutions of the patient plasma obtained on day 3 are indicated in the high-resolution gel. NHP denotes normal human plasma.