Assessment of IL-10 integrity and dimerization. Viral (a) and murine (b) IL-10, purified from transgenic tobacco leaf extracts by IMAC, were analyzed by immunoblotting after separation by non-reducing (left panels) and reducing (right panels) SDS-PAGE. Commercial recombinant viral IL-10 produced in E. coli (rvIL-10) or murine IL-10 produced in insect cells (rmIL-10) were used as controls, and different amounts of plant-derived IL-10 were loaded, as indicated on top of each lane. (c) Elution profile of plant-derived mIL-10 from a Superdex 200 column showing a single peak which, compared to the elution volumes of standard reference molecules on the same columns (not shown), matches with the expected size of the dimer. Detection of IL-10 in the elution fractions was carried out by ELISA.