TRANSCRIPTION OF THE INTERLEUKIN-4 GENE IS REGULATED BY MULTIPLE PROMOTER ELEMENTS

Activation of T helper cell 1 (Th1) and Th2 results in transcription o f the interleukin 2 (IL-2) and IL-4 cytokine genes, respectively. Wher eas many of the regulatory elements and factors responsible for IL-2 t ranscription in T cells are well defined, little is known about parall el mechanisms that drive transcription of the IL-4 gene. Here we have analyzed the murine IL-4 promoter, both in vivo and in a Th2 clone. 3 kb of IL-4 upstream sequence is shown to be sufficient to achieve tiss ue-specific and inducible expression of a thymidine kinase reporter ge ne in vivo in a manner that mirrors the expression of endogenous IL-4. Tissue-specific and inducible expression is also demonstrated in a Th 2 clone, but not in a B cell line. Deletional and mutational analysis of the IL-4 promoter demonstrated that sequences from -100 to -28 were necessary for a transcriptional response to Concanavalin A or anti-CD 3 monoclonal antibody. An overlapping, yet smaller region, spanning th e sequences from -60 to -28 bp was shown to be required for the respon se to ionomycin. Mutation of an 8-bp region from -43 to -35 of the IL- 4 promoter completely abrogated IL-4 gene transcription in response to all stimuli tested. In addition, our results show that the effects of the immunosuppressive agent Cyclosporin A map to the same DNA sequenc es as the positive control elements. These results identify DNA sequen ces that are functionally important for the control of IL-4 gene trans cription both in vivo and in vitro. Although these sequences are highl y conserved in the human and murine IL-4 genes, they are largely not p resent in the IL-2 enhancer complex. Thus, cytokine-specific cis-actin g elements may be one mechanism by which these two cytokine genes are differentially regulated.