Cloning of human interleukin-2 cDNA in E. coli by using oligonucleotide primers

Abstract

A cDNA clone for human interleukin-2 (IL-2) was isolated by using oligonucleotides as primers for the first and the second cDNA syntheses. Total RNA was prepared from Jurkat, a human leukaemic T-cell line, cells and mRNA was isolated. To synthesize ss-cDNA, a 30 mer oligonucleotide was used as a primer in the reverse transcriptase reaction. The sequence of the oligonucleotide was complementary to the 3' end of the coding sequence of IL-2. ds-cDNA was synthesized by DNA polymerase reaction using another oligonucleotide as a primer. A partial cDNA library was prepared using the ds-cDNA and screened for the presence of IL-2 cDNA by colony hybridization using the same oligonucleotides that were used in the cDNA synthesis reactions as probes. Three out of 200 transformants showed positive signals. Analysis of these three clones by restriction enzyme mapping and nucleotide sequencing showed that all of them contained IL-2 cDNA. Our results indicated that the IL-2 cDNA was enriched in the partial cDNA library about 300 fold over the population of IL-2 cDNA in the total cDNA library reported by Taniguchi et al. (1983).