Figure 5. Size fractionation of anti-BSA-digoxin bispecific serum.

(A) 200 µL of serum containing anti-BSA-digoxin bispecific antibody was fractionated on a Bio-Gel A1.5m column (a). Two distinct component peaks (peak 1 and peak 2) were obtained from the bispecific serum. A control, which consisted exclusively of IgG monomers, was separated on the same column with the same chromatographic conditions (b). The elution curves of bispecific serum and control overlapped after fractionation. (B) All 500 µL fractions of peak 1 and peak 2 were analyzed by bispecific antibody ELISA and their IgG nature was confirmed using a HRP conjugated goat anti-rabbit IgG antibody. The results were expressed as ELISA end point titers and plotted against the elution time.