Interferon-gamma transcriptionally modulates the expression of the genes for the high affinity IgG-Fc receptor and the 47-kDa cytosolic component of NADPH oxidase in human polymorphonuclear leukocytes

We examined the mechanisms responsible for the regulation by interferon-gamma (IFN-gamma) of the expression of the genes encoding the high affinity IgG-Fc receptor (Fc gamma R-I, CD64) and the NADPH oxidase 47-kDa cytosolic factor (p47-phox) in human polymorphonuclear leukocytes (PMN). Nuclear run-on transcriptional assays demonstrated that the Fc gamma R-I gene transcription is undetectable in untreated PMN but is significantly induced by IFN-gamma. Unlike Fc gamma R-I, p47-phox gene transcription is constitutively active in resting PMN and is down-regulated by a 2-h treatment of these cells with IFN-gamma. The transcriptional modulation by IFN-gamma of Fc gamma R-I and p47-phox genes is not influenced by the protein synthesis inhibitor cycloheximide. Moreover, Northern blot analysis revealed that cycloheximide superinduces p47-phox mRNA expression by increasing its half-life and without affecting p47-phox gene transcription. These findings indicate that human PMN can regulate gene expression by transcriptional and posttranscriptional events.