New directions in understanding interleukin-5 gene expression.

Specific regulation of the interleukin-5 (IL-5) gene is implied by the unique control of eosinophilia which is regulated by IL-5. In studies of IL-5 gene expression, the only control elements identified for the IL-5 gene have been transcriptional elements in the 5' untranslated region (UTR). Significant differences exist in the arrangement of the murine and human IL-5 promoters, which is surprising considering the tight regulation of the gene. Novel palindromic regulatory elements involved in transcriptional regulation have been found in the 5' UTR and new results show the presence of transcriptional elements in the 3' UTR. Post-transcriptional control mechanisms in both the 5' and 3' UTRs have also been described.