Table 1

Specific cytotoxicity of SS dsFv and (dsFv)2 immunotoxins

Cytotoxicity assays were performed by measuring incorporation of [3H]Leu into cellular proteins as described in “Materials and Methods.” IC50 is the concentration that causes 50% inhibition of protein synthesis after 20 h incubation with immunotoxin.








Cell lineMeso-antigenaIC50, pmoles


dsFv(dsFv)2Fold increase
A431/K5++++18257
N87++1801810
AGS++90234
A1847+12082
A431

>7770
>7770

  • a Antigen density was measured by immunofluorescence using K1 antibody (5). ++++, high; ++, medium; +, low; −, no expression of mesothelin.