Glycoprotein Ilb-IIIa is an abundant platelet receptor of the integrin family that play's a prinmr l role in platelet aggregation. It exists on the platelet surface predominantly in a resting or inactive conformation that is converted to an active binding competent conformation upon platelet activation. There is much interest in studying the difference between active and activity GP Ilb-IIIa, developing therapeutic agents targeted towards GP Ilb-Illa and developing diagnostic assays Cor antibodies that recognize epitopes on GP Ilb-IIIa. We present here the development of a large-scale process for purifying active GP Ilb-IIIa from human platelets. The procedure results in 25mg batch sizes of high purity and activity. Additionally. the effects of detergent concentration and impurities such as IgG on ELISA assays are examined. (C) 2002 Elsevier Science (USA). All rights reserved.