Patent ID: 7763430

Claim:
A method for detecting an anti-von Willebrand Factor-cleaving protease (“anti-vWF-cp”) antibody in a sample, where the antibody binds to a catalytic domain, a thrombospondin 2-8 domain, or a Cub domain of a vWF cp fragment, comprising the steps of (a) providing a solid phase comprising an immobilized vWF-cp fragment fused to a heterologous sequence that is separated from the vWF-cp fragment by a spacer, wherein the biological property of said vWF-cp fragment is not substantially impaired and the presentation of the epitopes of the vWF-cp fragment is not sterically impeded, and further, wherein the vWF-cp fragment comprises the catalytic domain, the thrombospondin 2-8 domain, or the Cub domain; (b) contacting a biological sample of a patient suspected of having thrombotic thrombocytopenic purpura (TTP) associated with occurrence of the anti-vWF-cp antibody with said immobilized vWF-cp fragment; and (c) detecting a complex of the anti-vWF-cp antibody and the vWF-cp fragment, wherein the presence of a complex with the catalytic domain is indicative of the presence of inhibitory antibodies that impair the catalytic function of substrate cleavage and the presence of a complex with the thrombospondin 2-8 domain or the cub domain is indicative of the presence of antibodies that do not inhibit substrate cleavage.