HIV-associated Thrombotic Thrombocytopenic Purpura - What We Know So Far

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening disease characterised by microvascular platelet deposition and thrombus formation in selected organs, resulting in microangiopathic haemolytic anaemia, thrombocytopenia, neurological symptoms and renal failure. Typically a very rare disorder, TTP is being seen with increased frequency in patients infected with the human immunodeficiency virus (HIV). Deficiency of the von Willebrand factor cleavage protease, ADAMTS13, has been implicated as the cause of TTP. However, the pathophysiology of HIV-associated TTP and the thrombotic potential in these patients are not known. This article provides not only an overview of the literature regarding HIV-associated TTP, but also presents new data on this disease. We propose a mechanism for the initial onset of HIV-associated TTP that includes the release of extreme amounts of von Willebrand factor and the downregulation of ADAMTS13 and/or the production of autoantibodies to ADAMTS13.