Molecular cloning of human and murine interleukin-2 genes and their expression in various host cells.

Interleukin-2 (IL-2), originally defined as a lymphokine which permits clonal expansion of T-cell clones, appears to elicit multiple biological activities in immune regulation. IL-2 cDNA cloning was one possible means to elucidate the whole structure of the IL-2 molecule and to obtain the molecule as a pure lymphokine in large quantity. The cloning and expression of human IL-2 cDNA is previously reported by us. Recently, we have obtained mouse IL-2 cDNA clone. Sequence analysis of the cloned cDNAs revealed that the murine IL-2 consists of 169 amino acids including a signal peptide. Interestingly, murine IL-2 appears to contain 12 glutamine residues in a row at the N-terminal region. Expression of this cDNA under the control of SV40 early promoter resulted in a typical mouse IL-2 activity. To reveal the structure, particularly potential regulatory elements of the IL-2 gene, we have cloned human and mouse IL-2 genes. Both genes are contained in a 7 kb genomic DNA fragment and blocked by 3 introns. The sizes of corresponding introns and exons between human and mouse are very similar to each other. The homology upstream from the TATA box is significantly higher than exon homology, implying the presence of regulatory sequence in this region.