Expression, Purification, and Refolding of Recombinant Fusion Protein hIL-2/mGM-CSF

ObjectiveTo study the activities of interleukin (IL)-2 and granulocyte-macrophage colony-stimulating factor (GM-CSF) (hIL-2/mGM-CSF).MethodsSOE PCR was used to change the linker of the fusion protein for higher activities. The fusion protein was expressed in Escherichia coli (E. coli) BL21 (DE3) in inclusion body (IB) form. After IB was extracted and clarified, it was denatured and purified by affinity chromatography. The protein was refolded by dilution in a L-arginine refolding buffer and refined by anion chromatography. The protein activity was detected by cytokine-dependent cell proliferation assay.ResultsThe expression of hIL-2/mGM-CSF in E. coli yielded approximately 20 mg protein /L culture and the purity was about 90%. The specific activities of IL-2 and GM-CSF were 5.4×106 IU/mg and 7.1×106 IU/mg, respectively.ConclusionThis research provides important information about the anti-tumor activity of hIL-2/mGM-CSF in vivo, thus facilitating future clinical research on hIL-2/mGM-CSF used in immune therapy.