Inhibition of the constitutive and induced IFN-beta production by IL-4 and IL-10 in murine peritoneal macrophages.

We had previously reported that freshly harvested peritoneal macrophages (PM) are in a type I IFN-mediated antiviral state, which is lost during in vitro culture of PM, concomitantly with a progressive decline in the expression of IFN-beta. We report herein that in vitro culture of PM in the presence of IL-4 or IL-10 results in an enhanced decay of the IFN-beta-mediated antiviral state to vesicular stomatitis virus (VSV). Moreover, IL-4 and IL-10 inhibited the production of type I IFN induced by LPS or NDV infection, as assessed by IFN production and induction of IFN-mediated antiviral state. The accumulation and physiological turnover of IFN-beta mRNA was not affected by IL-4 or IL-10. Finally, neither IL-10 nor IL-4 exerted any inhibitory effect on the antiviral activity induced by exogenous type-I IFN. These results suggest that Th2 cytokines, such as IL-4 and IL-10, act as negative regulators of the type I IFN-mediated antiviral response in PM and may represent stop signals for the constitutive or induced type I IFN expression in PM.