A Two Step Purification of Recombinant Human Interleukin-1β Expressed in E. Coli

Recombinant human interleukin-1β has been expressed in high yield using E. coli with a cDNA clone obtained from SKhep1RNA. The rIL-1β is purified to apparent homogeneity using freeze-thaw extractions followed by hydrophobic interaction chromatography over phenyl Sepharose. The procedure can provide pure rIL-1β (up to 15 mg per liter of E. coli culture) without the use of denaturants and if desired, in the absence of column chromatographic steps. Purity is defined by the presence of a single band on 1-D polyacrylamide gels and a single spot on 2-D polyacrylamide gels. The purified protein exhibits a biological activity of 1 × 10⁷ units/mg in a fibroblast proliferation assay and is shown to cross-react with rabbit anti-human IL-1β sera.