Figure 7.

Cytotoxicity of 4KB128-SAP (C1) produced in P. pastoris for CD22 ⁺ Daudi cells. Daudi cells were exposed for 72 hours to increasing concentrations of 4KBscFv-SAP (red triangles), seed SAP (light blue squares) or mock supernatant (violet circles) (A). Inhibition of protein synthesis is expressed as percentage of [³H]-leucine incorporation compared to untreated control cells. Error bars represent standard deviations from the mean of triplicate samples. (B) A competitive inhibition assay was performed by incubating Daudi cells for 72 hours with of 4KB128scFv-SAP at 10⁻⁸ M in the presence of increasing concentrations of 4KB128 parental monoclonal antibody (filled and open red circles refer to two different batches of 4KB128 MAb). Inhibition of protein synthesis is expressed as percentage of [³H]-leucine incorporation compared to untreated control cells. Error bars represent standard deviations from the means of triplicate samples. 4KB128 antibody used alone over the full concentration range was not cytotoxic.