A two step purification of recombinant human interleukin-1 beta expressed in E. coli

Recombinant human interleukin-1 beta has been expressed in high yield using E. coli with a cDNA clone obtained from SKhep1RNA. The rIL-1 beta is purified to apparent homogeneity using freeze-thaw extractions followed by hydrophobic interaction chromatography over phenyl Sepharose. The procedure can provide pure rIL-1 beta (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 x 10(7) units/mg in a fibroblast proliferation assay and is shown to cross-react with rabbit anti-human IL-1 beta sera.