Murine cells make inflammatory cytokines in response to influenza virus in a TLR7-dependent manner. (A) Peripheral blood leukocytes (10⁶ cells) from either wild-type or TLR7 knockout mice were treated with G-CSF (100 U/mL) and GM-CSF (100 U/mL) and then were stained with antibodies specific for 7/4 and F480. (B) Cells were stimulated with LPS (1 μg/mL), R-848 (10 μM), or influenza virus (Hong Kong, 500 000 HA), permeabilized, and stained for TNF. Results shown are for 7/4⁺/F480⁻ cells. (C) Peritoneal exudates cells (10⁶ cells) were stimulated with poly (I:C) (50 μg/mL), R-848 (3 μM), or the indicated amount of influenza virus (Hong Kong). Supernatants were collected at 24 hours and cytokines measured by ELISA. P ≤ .01 comparing R-848 or influenza in WT versus TLR7 KO or MyD88 KO by the 2-tailed paired t test. Data are means (± SD) of a representative experiment performed in single wells. Two other experiments yielded similar results. (D) Murine embryonic fibroblasts (5 × 10⁴ cells) were stimulated with poly (I:C) (50 μg/mL), R-848 (10 μM), or the indicated amount of influenza virus (Hong Kong), and supernatants were collected at 24 hours and cytokines measured by ELISA. P ≤ .01 comparing R-848 or influenza in WT versus TLR7 KO or MyD88 KO by the 2-tailed paired t test. Data are means (± SD) of a representative experiment performed in single wells. Two other experiments yielded similar results.