C57BL/6 female mice were fed a liquid ethanol (ETOH) diet (27% of calories derived from ETOH) for 5 months as an animal model of chronic alcohol use. A isocaloric liquid diet supplemented with maltose dextran was fed to controls. Splenocytes from ETOH-treated and control mice, and purified macrophages from normal mice and retrovirus infected mice were exposed in vitro to various concentrations of ETOH (0.1-1.0% v/v). The effect of chronic ETOH exposure in vivo, and of in vitro treatment with ETOH on tumor necrosis factor (TNF) and gamma-interferon (IFN) production by cultured murine splenocytes and purified macrophages was investigated. Dietary ethanol did not significantly affect in vitro TNF or IFN production. However, TNF and IFN production by splenocytes from mice fed either the ETOH or control diet decreased significantly when the cells were cultured with ETOH and stimulated with LPS or Con A in vitro. Thus ETOH in vitro directly down regulates TNF and IFN secretion by LPS- or Con A-stimulated spleen cells. ETOH treatment in vitro did not significantly change TNF production by purified peritoneal macrophage (PM) and thioglycollate-induced peritoneal macrophage (TPM) from normal mice, but increased TNF production by alveolar macrophage (AM). Although murine retrovirus infection per se increased TNF production it did not change the responsive pattern in TNF production of PM and TPM to ETOH in vitro and reduced the TNF production of AM.