LPS-induced SHIP induction prevents an enhanced antiviral response to a second dose of LPS. (A) MyD88^+/+ (□) and MyD88^−/− (■) BMmφs, tolerized with 10 ng/mL LPS for 24 hours, were untreated (0) or stimulated with 30 nM CpG, 5 μg/mL dsRNA, or 10 ng/mL LPS for 24 hours. Cell supernatants were then assessed for IFN-β by ELISA. Results are the mean plus or minus SEM for 3 independent experiments assayed in duplicate. *P < .01 compared with wild-type cells and comparing tolerized cells to untolerized cells. NS indicates not significant. Unstimulated cells did not produce detectable IFN-β. (B) SHIP^+/+ (□) and SHIP^−/− (■) BMmφs were untreated (C) or treated with 10 ng/mL LPS with or without a blocking antibody to TGF-β (αTGF-β) or an irrelevant isotype control (irrel) for 24 hours and then stimulated with 5 μg/mL dsRNA (left panel) or 10 ng/mL LPS (right panel) for 24 hours. Cell supernatants were assessed for IFN-β by ELISA. Results are the mean plus or minus SEM for 3 independent experiments assayed in duplicate. *P < .01 compared with LPS tolerized cells or cells tolerized in the presence of the isotype control antibody. NS indicates not significantly different from tolerized cells in the absence of antibody. (C) SHIP^+/+ (□) and SHIP^−/− (■) BMmφs were untreated (C) or treated with 20 ng/mL TGF-β for 8 hours followed by stimulation with either 5 μg/mL dsRNA or 10 ng/mL LPS for 24 hours. Cell supernatants were assessed for IFN-β by ELISA. Results are the mean plus or minus SEM of 4 independent experiments assayed in duplicate. *P < .001 compared with untreated cells. NS indicates not significant.