Research Article

A Human Recombinant Autoantibody-Based Immunotoxin Specific for the Fetal Acetylcholine Receptor Inhibits Rhabdomyosarcoma Growth In Vitro and in a Murine Transplantation Model

Figure 3

Colorimetric XTT cytotoxicity assays with various immunotoxin concentrations ( 𝑛 = 3 parallel cell cultures per dilution) showing strong dose-dependent toxicity of the immunotoxin scFv35-ETA directed against the acetylcholine receptor (AChR) 𝛾 -subunit on positive RMS cell lines TE671, RD, and FL-OH-1, RH-30 and Ax-OH-1 even at higher dilutions (a). Lower to no toxicity of the immunotoxin were observed towards the control cell lines A-204 and U937 not expressing fAChR (b). Competition of toxicity could be achieved with 1–100-fold molar excess (C 1.5–150 nM) of scFv35 added to cells incubated with 1.5 nM scFv35-ETA, whereas scFv35 alone does not inhibit cell growth even at 100 fold higher concentration (c). Cell viability is expressed as percentage inhibition of cell proliferation compared to non-treated cells.