Stability of scFv-Fc and scFv-Fc-RNase. (A) Samples of the CD30 specific scFv-Fc (dotted lines) and scFv-Fc-RNase proteins (solid lines) were incubated with 10% (vol/vol) FCS or HS at 37°C and 4°C for 1 to 5 days and used for flow cytometry analysis of CD30⁺ Karpas-299 cells and CD30⁻ HD-MY-Z. Cells only stained with secondary antibody were used as negative control. A total of 1 μg scFv-Fc and scFv-Fc-RNase of the protein preparation stored in PBS at 4°C were used as positive controls. Mean fluorescence values are shown. (B) Samples of scFv-Fc (top blot) and scFv-Fc-RNase (bottom blot) incubated for 1 to 5 days with 10% (vol/vol) FCS were also analyzed by SDS-PAGE, Western blot, and immunostaining using an AP-conjugated goat anti-human IgG (Fc-specific) antibody.