Spontaneous and cycloheximide-induced interleukin-10 mRNA expression in human mononuclear cells.

Interleukin-10 (IL-10) is known to be spontaneously produced by human peripheral blood mononuclear cells. In order to define the cell type in which IL-10 gene is spontaneously expressed we used the reverse polymerase chain reaction for IL-10 mRNA expression, which was also used to study the effects of cycloheximide (CHX). First, we found that IL-10 mRNA is spontaneously expressed in monocytes and B cells but not T cells from healthy donors, and second, we demonstrated that CHX superinduces IL-10 mRNA in monocytes and B cells. Experiments including nuclear run-on analyses established that the effects of CHX on IL-10 gene expression involve both gene transcription and mRNA stabilization.