The detection of a platelet-agglutinating factor in thrombotic thrombocytopenic purpura.

A sensitive and specific test was used to identify a platelet-agglutinating factor in sera from patients with thrombotic thrombocytopenic purpura. Serum from patients plus a preparation rich in large multimers of factor VIII: von Willebrand factor were added to target platelets, and agglutination occurred in 41 of 48 samples. Edetic acid, heparin, or heating, but not aspirin, monomeric IgG, or dansylarginine N-(3-ethyl-1,5-pentanediyl)amide …