Autoantibodies to alpha(IIb)beta(3) in patients with chronic immune thrombocytopenic purpura bind primarily to epitopes on alpha(IIb)

Chronic immune thrombocytopenic purpura (ITP) is an autoimmune disease caus ed by platelet destruction resulting from autoantibodies against platelet s urface proteins, particularly platelet glycoprotein IIb/IIIa (alpha (IIb)be ta (3)). To localize the auto-epitopes on platelet alpha (IIb)beta (3,) the binding of autoantibodies to Chinese hamster ovary (CHO) cells expressing either alpha (IIb)beta (3) or alpha (v)beta (3) was studied. Thirteen of 14 ITP autoantibodies bound only to CHO cells expressing alpha (IIb)beta (3). Because these 2 integrins have the same beta chain (beta (3)), these resul ts show that most epitopes in chronic ITP are dependent on the presence of glycoprotein alpha (IIb). (Blood, 2001;97:2171-2172) (C) 2001 by The Americ an Society of Hematology.