Regulation of interleukin-2 receptor gamma chain mRNA expression in human monocytic cell line THP-1

The interleukin-2 receptor (IL-2R) gamma chain (gamma c chain) is shared by IL-4R, IL-7R, IL-9R, and IL-15R and plays an important role in regulation of the immune system. However, its regulation in monocytic cell lines has not been well clarified. We examined the expression and regulation of the IL-2R alpha, IL-2R beta, gamma c chain, IL-4R and IL-7R mRNA in a human monoblastic leukemia cell line, THP-1. Unstimulated THP-1 cells constitutively expressed a low level of gamma c chain and IL-4R mRNA. Phorbol myristate acetate (PMA) induced macrophage-like differentiation and up-regulated the gamma c chain mRNA expression in THP-1 cells. This effect of PMA was suppressed by the protein kinase inhibitors H-7 and staurosporine. PMA did not affect the expression of the other IL-R mRNAs examined. 1 alpha, 25(OH)2D3 and interferon-gamma also induced differentiation of THP-1 cells, but these reagents did not affect the expression of the IL-R mRNAs in THP-1 cells. These findings suggest that the expression of the gamma c chain mRNA is regulated by the PMA-dependent pathway and is not associated with that of the other IL-R mRNAs.