The Induction of Interferon-α and Interferon-β mRNA in Human Natural Interferon-Producing Blood Leukocytes RequiresDe NovoProtein Synthesis

Abstract

The induction of interferon-α (IFN-α) and IFN-β niRNA in natural IFN producing (NIP) cells in cultures of human peripheral blood mononuclear cells (PBMCs), stimulated by glutaraldehyde-fixed Herpes simplex virus type 1 (HSV)-infected WISH cells, was studied. The protein synthesis inhibitor cycloheximide (CHX) totally prevented the appearance of both IFN-α and IFN-β mRNA, also in cultures supplemented with a conditioned medium (CM) assumed to contain soluble factors necessary for the IFN induction. However, when PBMCs were preincubated for 4 h in medium supplemented with fetal bovine serum (FBS) with or without addition of CM, the subsequent induction of IFN-α/β mRNA became partially resistant to CHX. In serum-free medium containing interleukin-3 (IL-3) or granulocyte-macrophage colony-stimulating factor (GM-CSF), the early induction of IFN-α mRNA became resistant to CHX, and, in contrast to FBS and CM supplemented medium, this was observed also without a preincubation of the PBMCs. In contrast, IL-1, IL-2, IL-4, IL-6, tumor necrosis factor-α (TNF-α), IFN-α, or IFN-γ had no such effects. Our results suggests that de novo synthesis of proteins normally is required for the induction of IFN-α/β mRNA. Such proteins might be cytokines, possibly CSFs, which in turn also may require protein synthesis for their actions. In contrast, the actual triggering signal provided by the HSV-inducer is independent of protein synthesis.