VWF induces conformational changes in ADAMTS13 at 37°C which are inhibited by prior labeling with the mAb Wh2-11-1.

ADAMTS13 from HEK293 cells was incubated with the mAb Wh2-11-1 and VWF under the following conditions: (I) ADAMTS13 was treated with VWF at 37°C prior to addition of Wh2-11-1. (II) ADAMTS13 was treated with Wh2-11-1 at 37°C followed by the addition of VWF. (III) ADAMTS13 was treated with VWF at 4°C prior to addition of Wh2-11-1. (IV) ADAMTS13 was treated with Wh2-11-1 at 4°C followed by the addition of VWF. *Reactivity of ADAMTS13 to Wh2-11-1 is significantly higher (p<.001) in the presence of VWF at 37°C. **There is no significant difference between the reactivity of Wh2-11-1 to ADAMTS13 in the presence or absence of VWF at 4°C (p = 0.083). Binding of mAb was monitored by flow cytometry. The figure represents data from one of five independent experiments.