Neutralization of TNF-induced (upper panel) and HIV-tat–induced (lower panel) adhesion of HL-60 cells to EC by antibodies against the adhesion proteins. EC were incubated with either HIV-tat (100 ng/mL) or TNF (100 ng/mL) for 6 hours at 37°C, washed, treated with the indicated antibodies (1:200 dilution) for 1 hour at room temperature, and then examined for adhesion to HL-60 cells as described in Fig 6. All determinations were made in triplicate.