PLATELET-FUNCTION IN AUTOIMMUNE (IDIOPATHIC) THROMBOCYTOPENIC PURPURA

Platelets play an essential role in the formation of haemostatic plugs . The quantitative defect of platelets in autoimmune (idiopathic) thro mbocytopenic purpura (ITP) can result in bleeding complications, but m ost ITP patients have platelets with normal or enhanced function. Plat elets in ITP are large, young, so-called ''stress'' platelets with inc reased platelet-associated autoimmune antibody (immunoglobulin G). You ng stress platelets are more functional platelets, and their presence may account for bleeding times in ITP patients that are shorter than w ould be predicted on the basis of the patients' (low) platelet counts. Some ITP patients have significant mucocutaneous bleeding with platel et counts >50 x 10(9) l(-1); this may be due to qualitative platelet d ysfunction (e.g. brought about by inhibitory antiplatelet autoantibodi es).