Presence of a platelet aggregating factor in the plasma of patients with thrombotic thrombocytopenic purpura (TTP) and its inhibition by normal plasma

Abstract

Three patients with thrombotic thrombocytopenic purpura (TTP) were treated by infusion of normal plasma with dramatic responses. The plasmas collected from these patients during relapse induced in vitro aggregation of washed platelets from both normal donors and the patients during remission. The platelet aggregating factor was not dialyzable or adsorbable by Al(OH)3 and was not inactivated by diisopropylfluorophosphate, hirudin, or heparin in the presence of normal amounts of antithrombin. In contrast to the platelet aggregation induced by platelet isoantibody, the platelet aggregating activity of TTP plasma diminished as a function of time when it was incubated with normal plasma at 37 degrees C. These observations suggest that at least some instances of TTP appear to be due to deficiency of a plasma inhibitor to counteract a platelet aggregating factor demonstrated to be present in the plasma of these patients.

Thrombotic thrombocytopenic purpura plasma enhances platelet–leucocyte interaction in vitro

“…TTP plasma induced formation of aPAg when incubated with normal whole blood (WB) . This observation was similar to those of earlier studies which proposed the presence of one or more PAg-promoting factors (PAPF) in the plasma of TTP patients (Lian et al, 1979;Tandon et al, 1994). However, prior studies have not addressed the possible involvement of leucocytes or erythrocytes in the formation of aPAg induced by TTP plasma.…”

“…It was previously shown that TTP plasma induced aggregation of normal platelets in vitro, indicating the presence of a platelet aggregate promoting factor (PAPF); preincubation with normal plasma neutralized this effect, suggesting the presence of an inhibitor of PAPF in normal plasma (Byrnes & Khurana, 1977;Lian et al, 1979Lian et al, , 1984. This observation supplied a rational basis for plasma therapy in TTP.…”

“…However, the aggregation method used by us differed from those used by others; e.g. Lian et al (1979) used washed platelets, not PRP.…”

Thrombotic thrombocytopenic purpura in pregnancy with maternal survival. Case report

“…A review of the literature has revealed 13 patients with TTP with maternal survival (Hill & Cooper 1968;Richardson & Smith 1968;Bernard et al 1969; Barrett & Marshall 1975;Bukowski et aZ. 1977;Byrnes 8c Khurana 1977;Fitzgibbons et al 1977;Lian et al 1979;Yang et al 1979;Walker et al 1980;Shinoda et al 1981;Atlas et al 1982;Kitchens 1982 . (1 98 l), some reported patients with TTP during pregnancy probably had eclampsia rather than TTP; therefore, patients with hypertension were excluded from consideration.…”