[Purification and some properties of platelet aggregating protein (PAP) from the plasma of a patient with thrombotic thrombocytopenic purpura].

A new platelet aggregating protein (PAP) was purified from the plasma of a patient with acute thrombotic thrombocytopenic purpura (TTP) using A1 (OH)3 adsorption, PEG fractionation, DEAE cellulose chromatography, lentil lectin Sepharose 4B chromatography and gel filtration HPLC. The M. W. of this PAP was estimated to be 59,000. It induced the aggregation of washed platelets from normal subjects and the same patient after recovery. The antigenic material was present in 2 out of 6 other TTP patients but was absent in 7 normal subjects, two patients with DIC and two patients with ITP. The aggregation of washed platelets by PAP was concentration dependent and required energy metabolism, Ca2+ and fibrinogen. PAP was present in the plasma of a subset of TTP patients and was likely the cause of platelet thrombi in the microvessels in these patients.