Figure 4.

PD-1 binding and PD-1/PD-L1 binding blockade profiles of mouse anti-PD-1 monoclonal antibodies. (a) PD-1 binding profile of selected mouse anti-PD-1 mAbs assessed by ELISA. Serial dilutions of each purified mouse anti-PD-1 mAb were added to the hPD-1 His tag-coated ELISA plate. HRP-conjugated goat anti-mouse IgG Fc-γ was used for detection. The absorbance at 492 nm was measured. Data from triplicates are presented as the mean ± SD. (b) PD-1/PD-L1 binding blockade profile of selected mouse anti-PD-1 mAbs assessed by the PD-1/PD-L1 blockade bioassay. Serial dilutions of each purified mouse anti-PD-1 mAb and hPD-1-expressing Jurkat cell were added to an assay plate harboring precultured PD-L1-expressing CHO-K1 cells. After coculture for 6 h, Bio-Glo was added, and the luminescence signals were measured. The results from triplicates are presented as a relative light unit (RLU) as the mean ± SD. Commercially available anti-PD-1 mAbs, KEYTRUDA and OPDIVO, were used as positive controls, while human IgG4/κ was used as a negative control.