Figure 5. Stability tests. (A) IgG and IgG-RNase were incubated in 50% mouse serum at 37 °C for up to 24 h followed by testing of binding to the corresponding antigen by ELISA. Detection was done with an anti-human IgG-Fc specific secondary antibody HRP conjugate. (B) MN-IgG-RNase and (C) CTX-IgG-RNase were also tested by incubation in 50% human or mouse serum at 37 °C for up to 7 d followed by a novel immunoassay combining ELISA with an RNase activity assay. BSA was used as negative control antigen. All binding and activity data were normalized to values measured with samples freshly thawed (time 0 = 100%).