Virus-associated idiopathic thrombocytopenic purpura

Two-thirds of children with acute idiopathic thrombocytopenic purpura (ITP) have a history of an infectious illness a few days to a few weeks before t he onset of thrombocytopenia. In a subset of affected children, identificat ion of a specific virus can be made, such as varicella tester virus, rubell a, Epstein-Barr virus, influenza, or human immunodeficiency type I virus, i ndicating an etiological role for preceding viral infection in these childr en with ITP. While inhibition of thrombopoiesis has; been established to pl ay a role in thrombocytopenia associated with infection with some viruses, it does not appear to play a major role in the etiology of most typical ITP cases. Rather, enhanced clearance of platelets by the reticuloendothelial system is considered to be, at least in part, responsible for the thrombocy topenia which occurs during the viremic phase of acute virus infection or w hich develops days to weeks following the virus illness. Molecular mimicry between viral antigens and host proteins has been implicated in a number of autoimmune phenomena, and may be involved in the enhanced platelet clearan ce in virus-associated ITP. (C) 1998 Elsevier Science Ltd. All rights reser ved.