PLANT-PRODUCED RECOMBINANT HUMAN INTERLEUKIN-2 AND ITS ACTIVITY AGAINST SPLENIC CD4 + T-CELLS

Recombinant human interleukin-2 (rhIL-2) is a biopharmaceutical protein of great importance, as it is the standard FDA-approved immunotherapeutic treatment for end-stage metastatic melanoma and renal cell cancer. In this study, we explored the feasibility of producing biologically active rhIL- 2 in the green tissues of transgenic tobacco (Nicotiana benthamiana). Production of rhIL-2 proteins in whole-plant expression system will be more economical when compared to the current E. coli based expression system. The human rhIL-2 gene was codon optimized to maximize plant host system expression. A construct fusing red fluorescent protein to rhIL-2 was developed, and confocal microscopy was utilized to verify the targeted rhIL-2 accumulation, and its proper folding in this system. Five additional plant-specific transgene constructs were developed for stable expression rhIL-2 with targeting to each sub-cellular compartment. Western blotting of the stably transformed lines demonstrated accumulation of the appropriately sized rhIL-2 protein in the endoplasmic reticulum and chloroplasts. The plant-produced rhIL-2 was purified, and its biological activity was compared with that of commercially available E. coli produced rhIL-2 on murine splenic CD4+ T- cells from C57BL/6 mice. This research demonstrated the efficacy of using tobacco as an expression system for the production of biologically active rhIL-2.