Expression and in vitro function of anti-PD-L1 human antibody expressed in plant

Plants can be used to produce recombinant functional proteins such as antibodies and vaccines. In this study, transgenic plants were utilized to express anti-human programmed death ligand-1 (PD-L1) monoclonal antibodies (mAb(P) PD-L1) tagged with the endoplasmic reticulum retention motif KDEL. PCR and immunoblot analyses confirmed that mAb PD-L1 was expressed in transgenic plants. ELISA analysis confirmed the binding activity of mAb(P) PD-L1 to human prostate and urothelial cancer cell lines PC-3 and TCCSUP, respectively. Confocal imaging analysis demonstrated that mAb(P) PD-L1 had binding activity against human cancer cell lines similar to Avelumab (mAb(M) PD-L1). Confocal imaging analysis showed that the binding activity of mAb(P) PD-L1 to the human tonsil is comparable to mAb(M) PD-L1. These results suggest that mAb(P) PD-L1 shows functional binding activities for PD-L1(+) cancer cells. Hence, this study showed that tobacco plants can be used to produce functional anti-human PD-L1 mAbs.