A recombinant plasmid containing expression units for human pre‐interleukin 2 (pre‐IL‐2) and the selectable marker mouse DHFR, was constructed and used to transform DHFR− CHO cells to the DHFR+ phenotype. Selected colonies were isolated and tested for IL‐2 production. Twelve highly IL‐2‐producing clones were amplified in stepwise increasing concentrations of methotrexate. The IL‐2 secreted into the culture medium by one of these clones was purified to homogeneity and partially characterized. N‐terminal sequence analysis showed that pre‐IL‐2 was correctly processed during secretion. SDS gel electrophoresis and chromatofocusing experiments in conjunction with neuraminidase treatment indicated a posttranslational glycosylation of the secreted mature protein similar to that described for the tetrasaccharide structure of the N2 form of natural IL‐2. This recombinant IL‐2 has a specific activity of 2.5 × 107 U/mg.

No abstract

No abstract

No abstract