alpha 1-Antitrypsin therapy in a case of thrombotic thrombocytopenic purpura.

In thrombotic thrombocytopenic purpura (TTP), activated leucocytes release elastase which mobilises unusually large von Willebrand factor (vWF) multimers from the endothelium. We investigated the effect of an inhibitor of leucocyte elastase (alpha 1-antitrypsin) on circulating vWF and platelet count in a patient with chronic relapsing TTP. alpha 1-antitrypsin consistently normalised vWF multimeric composition but failed to increase platelet count and induce remission. Plasma cryosupernatant, which never normalised vWF, always induced laboratory and clinical remission within 96 hours. In chronic relapsing TTP, unusually large vWF multimers are not the main cause of intravascular platelet aggregation.