A HIGHLY SENSITIVE AND SPECIFIC ASSAY USING A NOVEL HUMAN GROWTH-HORMONE CDNA REPORTER GENE REGULATED BY THE HUMAN INTERLEUKIN-4 INDUCIBLE GERMLINE EPSILON-TRANSCRIPT PROMOTER

We have successfully developed a highly sensitive and specific assay s ystem for human interleukin-4 (IL-4) regulated gene expression. It is based on a human Jijoye cell line with the germline epsilon transcript promoter joined to the human growth hormone (hGH) cDNA. The germline epsilon transcript promoter is responsive to IL-4 and involved in immu noglobulin heavy chain class switching. We cloned hGH complementary DN A (cDNA) as the reporter gene instead of using conventional hGH genomi c DNA which failed to generate any IL-4 inducible clone in human Jijoy e cells. The two IL-4 inducible cell lines with the hGH cDNA reporter show high signal/noise ratio for IL-4-mediated induction (60-90 fold). The response to IL-4 is dose-dependent with ED50 of 10 pM. As expecte d, there is no response to other human cytokines and growth factors, a s well as mouse IL-4. The mutant hIL-4 antagonist hIL-4.Y124D inhibits the induction mediated by native hIL-4. These IL-4 inducible cell Lin es provide a sensitive, specific assay system to study IL-4-regulated gene expression, and in particular the regulation of the germline epsi lon promoter. (C) 1998 Elsevier Science B.V. All rights reserved.