Molecular Immunology

Abstract

GM!CSF is a cytokine with pleiotropic biological activities and is increasingly used in clinical trials[ The present study demonstrates the ability of recombinant human granulocyte!macrophage colony!stimulating factor "rGM!CSF# to induce elevation of interleukin! 09 "IL!09# mRNA and protein production in the monocytic cell line U826[ As shown by a semiquantitative reverse transcriptase! polymerase chain reaction "RT!PCR#\ IL!09 mRNA increases up to 09 times when stimulated with rGM!CSF "099 U:ml# compared to nonstimulated control cells[ Maximal IL!09 mRNA expression occurs at 5 h and remains high for 1 h[ Thereafter IL!09 mRNA is downregulated and reaches basal level at approximately 13 h[ IL!09 protein was measured by ELISA[ The protein yield is dose! dependent on the rGM!CSF concentration[ Combined stimulation of U826 cells with both GM!CSF and TNF!alpha results in an additive elevation of the IL!09 protein yield[ Application of a neutralising antibody against TNF!alpha revealed that GM!CSF induces IL!09 expression independently from TNF!alpha[ By using a luciferase reporter gene it was shown that rGM!CSF enhances IL!09 promoter activity 1
2!fold in a transient transfection assay.