Purification of recombinant human interferon-ε and oligonucleotide microarray analysis of interferon-ε-regulated genes

Recently identified interferon-ε (IFN-ε) belongs to type I interferons. IFN-ε is highly and constitutively expressed in the brain, but its biochemical and biological characteristics are poorly understood. In this study, full-length IFN-ε cDNA was cloned from human peripheral blood lymphocyte by RT-PCR, and was expressed in Escherichia coli (E. coli). Reverse phase high pressure liquid chromatography was used to purify recombinant human IFN-ε (rhIFN-ε) and to facilitate refolding of the protein. About 0.8 mg of highly purified rhIFN-ε protein was obtained from 100 ml of E. coli culture. Functional study of rhIFN-ε demonstrated that the antiviral activity of rhIFN-ε was 6 ± 0.5 × 105 IU/mg, which was lower than that of rhIFN-α-2b in the WISH-VSV (WISH cells infected with vesicular stomatitis virus) assay system. As for the activity to promote NK cytotoxicity and antiproliferation activities, rhIFN-ε was about 60 times less potent than rhIFN-α-2b. However, oligonucleotide microarray analyses revealed dramatic differences in gene expression profiles of cultured human cells treated with IFN-ε and IFN-α-2b. Particularly, differential regulation of genes related to central nervous system by rhIFN-ε suggests a role for IFN-ε in maintenance of the structure and function of brain.