PLATELET-RELEASE REACTION DURING EDTA-INDUCED PLATELET AGGLUTINATIONS AND INHIBITION OF EDTA-INDUCED PLATELET AGGLUTINATION BY ANTI-GLYCOPROTEIN IIB/IIIA COMPLEX MONOCLONAL-ANTIBODY

To characterize the nature of EDTA-induced platelet agglutination, the spontaneous release of beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4) was examined during EDTA-induced platelet agglutinations. A slight release of beta-TG and PF4 was observed when EDTA-anticoagulated whole blood from cases with EDTA-induced platelet agglutination was kept for 60 minutes, whereas a high spontaneous release of these proteins was found from normal blood anticoagulated with EDTA. These findings imply that EDTA-dependent platelet agglutinin may stabilize the platelet membrane surfaces. Secondly, we found that pretreatment of fresh blood with anti-glycoprotein (GP) IIb/IIIa complex monoclonal antibody dramatically reduced EDTA-induced platelet agglutinations. This study indicated that the binding sites of EDTA-dependent antibody might be GP IIb/IIIa complex. The use of an anti-GP IIb/IIIa complex monoclonal antibody may be useful in avoiding analytical errors in some cases with EDTA-induced pseudothrombocytopenia.