Anti-Endothelial Cell Antibodies in Thrombotic Thrombocytopenic Purpura and Haemolytic Uraemic Syndrome

Abstract

Thrombotic thrombocytopenic purpura (TTP) and haemolytic-uraemic syndrome (HUS), are rare and poorly understood disorders involving multiorgan microvascular platelet thrombus formation and microangiopathic haemolytic anaemic (Kaplan et al, 1992; Kaplan 1992; White et al, 1988). Only in HUS has an initiating pathologic stimulus been identified in the form of toxins associated with specific enteric infections (i.e., E Coli, Shigella)(Karmali et al., 1983; Karmali, 1989; Kavi and Wise, 1989). Because of the effectiveness of plasma exchange therapy (Moake, 1991; Rocketal, 1992; Bell et al, 1991) workers have looked for circulating factors that might explain the therapeutic response. Several have been detected, most notably, abnormally large high molecular weight von Willebrand multimers (Rose et al., 1984) a calcium-dependent cysteine protease (Murphy et al, 1987) and a platelet aggregating protein (p37) (Siddiqui et al, 1985). All these factors reflect responses to a damaging stimulus and are implicated in platelet activation, aggregation and deposition (Moake and McPherson, 1989; Moore et al, 1990; Lian et al, 1991).