MORAb-003 mediates tumor cytotoxicity via CDC in vitro. (A) FACS analyses on ovarian cancer lines and one breast cancer line measuring FRα expression levels. Cells were stained with MORAb-003 or an isotype control IgG. (B) IGROV-1 cells were treated with 10 µg/ml of MORAb-003 in the presence of 20% of fresh human serum and incubated for 1 hour at 37°C. Cells were counted via trypan blue exclusion and the number of dead cells after treatment was expressed as the percentage of the number of viable cells before the treatment (% cytotoxicity). (C) MORAb-003 killed CHO-FR cells via a CDC mechanism (assay conditions as in panel B). Compl. corresponds to fresh human serum.