Table 2

Cell viability assay (WST-1) of e23 dsFv and (dsFv)2 immunotoxinsa

Cell linee23 antigen densitybIC50 (ng/ml)Activity ratioc
dsFv(dsFv)2
A431+2.90.2412.1
MCF7+3.30.1818.1
SK-BR-3++++3.31.13.0
  • a Cell viability assays were performed as described in “Materials and Methods.” The IC50 is the concentration that causes 50% reduction of (A450 nm) value after 3 days of incubation with immunotoxin.

  • b +, low expression; ++++, high expression of erbB2.

  • c The activity ratio was calculated by dividing the IC50 of dsFv by that of the (dsFv)2.