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

The interleukin-2 receptor γ chain (IL-2Rγ) 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-2Rγ gene constitutively or after activation by IL-2 or interferon γ (IFNγ). Fresh human monocytes constitutively expressed low but significant levels of IL- 2Rγ mRNA, and nuclear run-on experiments showed that IL-2Rγ gene was transcriptionally active. Stimulation with IL-2 or IFNγ induced a major increase of IL-2Rγ mRNA in a time- and a dose-dependent manner. However, neither cytokine increased the transcriptional activity of the gene. The enhancement of IL-2Rγ mRNA expression by either IL-2 or IFNγ was concomitant with the stabilization of the mRNA, suggesting a posttranscriptional level of control. Finally, the augmented expression of IL-2Rγ in IL-2- and IFNγ-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-2Rγ gene in nonlymphoid cells and of its modulation by IL-2 and IFNγ through posttranscriptional mechanisms.