MEASUREMENT OF PLATELET MICROPARTICLES DURING CARDIOPULMONARY BYPASS BY MEANS OF CAPTURED ELISA FOR GPIIB IIIA/

A captured enzyme-linked immunosorbent assay (ELISA) using the disinte grin, kistrin, is described and used to measure platelet microparticle s (PMP) generated during open heart surgery. This ELISA detects 75 ng/ ml of glycoprotein IIb/IIIa (GPIIa/IIIa) in solution and is more sensi tive and less variable than flow cytometry and radioimmunoassay. By EL ISA, mean values of GPIIb/IIIa in PMP are 14.2 +/- 7.9 mu g/ml for out dated platelets and 0.28 +/- 0.1 mu g/ml in fresh blood from healthy d onors. Normal washed platelets (10(8)) contain 8.8 mu g of GPIIb/IIIa. In 12 cardiac surgical patients, PMP measured by ELISA significantlp increased (p = 0.039) to 0.58 +/- 0.3 mu g/ml at the end of cardiopulm onary bypass, but the increase measured by flow cptometry (1207 to 144 7 events in PMP gate) was not significant. Neither heparin nor protami ne alter PMP. After cardiopulmonary bypass, PMP concentrations return to baseline values before protamine is given. Concentrations of PMP in pericardial blood are greater than in simultaneous perfusare. This EL ISA is more sensitive and accurate than alternate methods for measurin g PMP and shows the PhifP production and rapid clearance during open c ardiac surgery.