Regulation by interleukin-2 (IL-2) and interferon gamma of IL-2 receptor gamma chain gene expression in human monocytes.

The interleukin-2 receptor gamma chain (IL-2R gamma) gene codes for a subunit of the IL-2R and is expressed in human lymphoid cells. The present study was undertaken to determine whether human monocytes expressed the IL-2R gamma gene constitutively or after activation by IL-2 or interferon gamma (IFN gamma). Fresh human monocytes constitutively expressed low but significant levels of IL-2R gamma mRNA, and nuclear run-on experiments showed that IL-2R gamma gene was transcriptionally active. Stimulation with IL-2 or IFN gamma induced a major increase of IL-2R gamma mRNA in a time- and a dose-dependent manner. However, neither cytokine increased the transcriptional activity of the gene. The enhancement of IL-2R gamma mRNA expression by either IL-2 or IFN gamma was concomitant with the stabilization of the mRNA, suggesting a postranscriptional level of control. Finally, the augmented expression of IL-2R gamma in IL-2- and IFN gamma-treated monocytes was associated with an increased IL-2-binding activity, compared with that of unstimulated cells. These results provide the first evidence of the expression of the IL-2R gamma gene in nonlymphoid cells and of its modulation by IL-2 and IFN gamma through posttranscriptional mechanisms.