The radioisotope labelling of thrombocytes using a monoclonal antibody against membrane glycoproteins IIb-IIIa and the measurement of thrombocyte adhesion/aggregation on the substrate surface]

A new method for platelet labeling based on binding of monoclonal antibody to human platelets has been suggested in this study. Monoclonal antibody VM16a against membrane glycoproteins IIb-IIIa was labeled by 125I and then incubated with platelets. About 70% of added antibody was bound when it was used at the concentrations corresponding to the linear part of the concentration curve (0.5 and 1.0 micrograms/ml). Due to high efficiency of binding 125I-VM16a-labeled platelets were used for the measurement of adhesion/aggregation to the substrate in platelet-rich plasma without washing of the free label. Experiments with washed platelets double labeled with 51Cr and 125I-VM 6a showed high correlation between the data obtained with both labels. The method of platelet labeling has been applied for the assessment of drug action on platelet adhesion/aggregation. Measurements were performed in platelet-rich plasma and adhesion/aggregation was stimulated by ADP and analogue of thromboxane A2, U46619. It was shown/that antianginal drug trapidil strongly inhibited and antiatherogenic drug probucol did not affect platelet adhesion/aggregation stimulated by both agonists.