Production, Purification and Immuno-Modulatory Actions of E. coli-derived Recombinant Human Interleukin 4

Abstract

The recombinant human interleukin 4 (rhIL-4) has been over expressed in E. coli transformed with expression vector pET-3b containing bacteriophage T7 promoter, into which the hIL-4 cDNA was subclond. The insolubility of the recombinant protein offered an advantage of purification in only a few steps. The recombinant human IL-4 was refolded using reduced/oxidized glutathione to restore the proper conformation and purified to homogeneity by one passage over ion exchange column. The purified protein was shown as a single band on SDS-PAGE. The refolded rhIL-4 was characterized by nucleotide sequence analysis and bioassays. The purified rhIL-4 has biological activities on B cell proliferation and induction of B cell differentiation antigen, CD23, which strongly indicates that the protein is folded correctly.