KINETICS OF PLATELETS IN DOGS WITH THROMBOCYTOPENIA INDUCED BY ANTIGLYCOPROTEIN IIB IIIA RECEPTOR MONOCLONAL-ANTIBODY/

To experimentally assess the kinetics of platelets in thrombocytopenia , we constructed a canine model using In-111-oxine labeled autologous platelets and an intact antiplatelet monoclonal antibody (MAb) NNKY2-1 1 (IgG2a). With the infusion of radiolabeled autologous platelets into dogs, the peripheral platelet count and blood radioactivity level wer e examined, and the radioactivity in the liver, spleen and heart was d etermined with scintigraphic analysis. Thereafter, i.v. injection of 1 00 mu g/kg of NNKY2-11 had no effect on platelet counts or the biodist ribution of radiolabeled platelets. However, 200 and 300 mu g/kg of MA b reduced the platelets, and the radioactivity of the liver and spleen augmented clearly after injection of MAb. Platelet radioactivity in s erum, which had decreased after MAb infusion, did not recover, even wh en peripheral platelet counts returned to the normal levels, indicatin g that these new platelets might be derived from the platelet-storage pool or new thrombocytogenesis. This model of antiplatelet MAb induced thrombocytopenia seems to be useful for analyzing the kinetics of pla telets in thrombocytopenia.