Thrombotic thrombocytopenic purpura (TTP) is a life-threatening disease caused by a deficiency in ADAMTS13 which in the acquired form is provoked by autoantibodies against this protease. The main objective of this work was to study the pathophysiologic and prognostic value of anti-ADAMTS13 antibodies in patients with acquired TTP. The surveyed antibody profile revealed the presence of mainly IgG followed by IgA and IgM antibodies. IgG1-4 and IgA ADAMTS13-specific immune complex (ICs) were detected. IgG4 was the most prevalent IgG subclass, present either as free antibody or as ICs. IgG...