Table 3

Relative binding affinity of e23 dsFv and (dsFv)2 immunotoxinsa

AnalyteTracerAffinity (nm)Cell lineAntigen
e23 IgGe23 IgG5N87+++
e23 dsFv-PE38e23 IgG160N87+++
e23 (dsFv)2-PE38e23 IgG8.1N87+++
e23 dsFv-PE38e23 IgG100A431+
e23 (dsFv)2-PE38e23 IgG35A431+
  • a The affinities of the dsFv and (dsFv)2 immunotoxins were determined by competition binding analysis to cells expressing e23 antigen. The antigen-positive cells used were A431 and N87. The relative binding affinity was calculated from the concentration of competitor that caused 50% inhibition of the binding of 125I-e23 IgG to the e23-expressing cell line.