Nickel chelate chromatography of human immune interferon

This chapter discusses the nickel chelate chromatography of human immune interferon. Human immune interferon is prepared from peripheral blood lymphocytes, which had been stimulated with staphylococcal enterotoxin A (SEA). Interferon is concentrated by chromatography on the columns of silicic acid and eluted with 0.3 M (CH₃)₄NCI in phosphate-buffered saline (PBS). In some experiments, silicic acid concentrated interferon is further purified by gel filtration on Ultragel AcA54 eluted with 1.0 M NaCl in PBS before Ni²⁺chelate chromatography is performed. Interferon is assayed on human WISH cells by estimation of the reduction of cytopathic effect; interferon activity is expressed in terms of National Institutes of Health reference standard. Columns of epoxy activated Sepharose 6B, which have not been previously used, are flushed with 0.05 M EDTA in 1.0 M Sodium Chloride (NaCl) to remove any metal ions, which have been inadvertently bound to the resin. The EDTA is then flushed from the column with Buffer A before charging the resin with Ni²⁺.