The displacement of platelet TM-60 binding to GFP by HK. Gel-filtered platelets were incubated with increasing concentrations of biotinylated TM-60 in the presence of 1.3 μmol/L HK at 23°C. Measurement of the bound fluorescence shows that HK could directly compete for TM-60 binding to platelets at low antibody concentrations. The effect could be almost abolished at higher antibody concentrations greater than 60 nmol/L.