FACS analysis of bispecific antibodies binding to the CD30⁺ L540CY Hodgkin cell line and to CD16⁺granulocytes. The tumor cells and the granulocytes were incubated with 20 μg of the parental biMoAb HRS-3/A9 or with 20 μg of the anti-CD16/anti-CD30 diabody. The binding of the anti-CD16/anti-CD30 diabody to L540CY cells and granulocytes was detected with the anti–c-myc immunotag antibody 9E10 and fluorescein-conjugated goat antimouse IgG. Bound BiMoAb HRS-3/A9 was detected with fluorescein-conjugated goat antimouse IgG. As a negative control, target cells were incubated with 9E10 and FITC-labeled goat antimouse IgG alone.