[Multimeric composition of von Willebrand factor in thrombotic thrombocytopenic purpura. Japanese TTP Study Group].

Thrombotic thrombocytopenic purpura (TTP) is an uncommon disorder. Several hypotheses have been reported up to now but, the pathogenesis is not yet clear. On the other hand, von Willebrand factor (vWf) plays a role in platelet agglutination in initial hemostasis. Moake and other investigators suggested plasma vWf abnormalities. In this paper, we analysed vWf antigen, ristocetin cofactor (RCof) and multimeric composition of vWf in 16 patients with TTP. It was found that vWf antigen and RCof ranged from very low to very high levels, but RCof was lower than vWf antigen except in two cases. Decrease of large multimer of vWf was seen in 11 patients (69%). These abnormalities were corrected at remission by therapy.