Biopharmaceutical production in plants: problems, solutions and opportunities.

There are major structural differences between plant and mammalian N-linked glycans, with those from plants being immunogenic in most laboratory mammals and eliciting glycan-specific IgE and IgG antibodies in humans, when delivered parenterally. However, because humans are constantly exposed to plant glycoproteins in the diet, glycosylated plant-made pharmaceuticals (PMPs) should be acceptable for topical and oral administration. To exploit fully the potential that plants offer for the production of therapeutic proteins for parenteral administration, it might be necessary to inhibit plant-specific post-translational modifications to obtain "humanized" non-immunogenic N-glycans on PMPs. The benefits that could accrue are lower manufacturing costs, relative to mammalian cell culture, and a reduced risk of transmission of mammalian pathogens.