Growth phase-dependent expression of proteins with decreased plant-specific N-glycans and immunogenicity in tobacco BY2 cells.

Plants possess some desirable characteristics to synthesize recombinant glycoproteins for pharmaceutical application. However, the mammalian glycoproteins produced in plants are somewhat different from their natural counterparts in terms of N-glycoforms. The immunogenicity of plant-specific glyco-epitopes is the major concern in human therapy. Here, the distribution of N-glycans in different growth phases of tobacco BY2 cells and their immunogenicity in mice were determined. It was observed that the percentage of beta1,2-xylose and alpha1,3-fucose in proteins of growing cells increased and the corresponding protein extracts caused accelerated immune response in mice. Based on this observation, the recombinant erythropoietin in BY2 cells was expressed and characterized, and Western blot analysis showed that the recombinant erythropoietin contained a relatively small amount of plant-specific glyco-epitopes in the early phase of culture growth. This study may provide a simple but effective strategy for the production of therapeutic glycoproteins with human-like N-glycan structures in plant hosts to avoid a great allergenic risk.