Table 1.

Comparison of binding of 4D5scFv and the Grababody 4D5scFvZZ to different cell lines in FACS analysis

4D5scFv4D5scFvZZh4D5
16.7 nmol/L (0.5 μg/mL)167 nmol/L (5 μg/mL)14.3 nmol/L (0.5 μg/mL)143 nmol/L (5 μg/mL)66.7 nmol/L (10 μg/mL)
T6-17255.0279.0406.02355.0901.2
SKBR359.239.665.2396.2313.8
BT474332.8228.1121.9489.7377.7

NOTE: Mean fluorescence intensity readouts of each protein construct at indicated concentration were listed. The maximal binding (in bold) was the highest mean fluorescence observed in the FACS analysis. Anti-His probe and Alexa-488 labeled anti-rabbit IgG antibodies were used subsequently to detect the His-tagged 4D5scFv and 4D5scFvZZ. To show relative receptor expression levels among these cell lines, binding of the h4D5 antibody was included. h4D5 was detected by a different secondary FITC-labeled anti-human antibody, which had background readout of 3.0–4.3 in these 3 cell lines.