Two regions within the human IL-2 gene promoter are important for inducible IL-2 expression

We have examined regulatory domains of the human IL-2 gene promoter by transfection and transient expression of rDNA constructs in which the chloramphenicol acetyl transferase gene shows T cell-specific inducible expression and cyclosporin A-mediated inhibition when placed downstream of 587 bp of the human IL-2 5'-flanking region. A series of 5'-deletion constructs transfected into the Jurkat T lymphoid line demonstrates that a region encompassing 370 bp 5' of the transcription start site is sufficient for inducible chloramphenicol acetyl-transferase expression. Further dissection of this region with internal deletion (linker-scanner) mutants revealed that portions of at least two discrete regions from -42 to -169 and -289 to -361 bp relative to the transcription start site are critical for inducible expression of the IL-2 gene. T cell-specific expression of wild-type and mutant IL-2 promoter constructs could be increased severalfold by the insertion of an upstream SV40 enhancer. With use of a battery of IL-2 promoter constructs, we could not identify subregions within IL-2 5'-flanking sequences which are crucial for cyclosporin A inhibition of the IL-2 gene or deletion of which resulted in loss of T cell-specific expression, suggesting that such functions may be mediated at pre-transcriptional levels.