Rapid Affinity Maturation of Novel Anti-PD-L1 Antibodies by a Fast Drop of the Antigen Concentration and FACS Selection of Yeast Libraries

Figure 5

Binding and biological activity of the affinity matured mAb 10_3 on human lymphocytes. (a) The graph shows the binding curve of the selected mAb 10_3 to activated hPBMCs expressing PD-L1, in comparison with the wild type IgG. The binding was evaluated by flow cytometry, and the MFI of the CD2-positive cells bound to the IgGs was plotted against IgG concentration. The apparent affinity constant of the novel mAb 10_3 and its fold increase are reported. (b) The curves represents the effects of the affinity matured anti-PD-L1 mAb 10_3 on cytokine secretion of T cells after stimulation. hPBMCs were stimulated with PHA (2.5 μg/mL) or SEB (50 ng/mL) in the absence or in the presence of the wild type antibody or its derived antibody 10_3. IL-2 and IFN-γ levels were measured in the supernatants by ELISA at different timepoints. An unrelated antibody was used as a negative control. Cytokine levels were reported as the mean of at least two determinations obtained in two independent experiments. Error bars indicate mean ± SD. values for the cytokine concentration obtained with mAb 10_3 relative to the wild type mAb: .

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