Some unsettled questions in childhood thrombocytopenia caused by immunologic platelet destruction (acute and chronic ITP).

The cause of idiopathic thrombocytopenia (ITP) is largely unknown, although the underlying pathophysology is an autoimmune process. Anti-idiotypic antibodies and their role on regulatory T-cells might play an important role in the switch from acute to chronic ITP. The exact interaction remains to be elucidated. The effects of the dysregulated immune system and of the autoimmune process on thrombocytopoiesis and megakaryopiesis are ill defined. Therapy of acute and chronic ITP is directed to the risk of bleeding.