Induction of CCR2 ligands is dependent on the IFNAR1-triggered signaling. (A) Gr1 + CD11b + myeloid cells were isolated from the lungs of PR8-infected WT, MyD88-/- and IFNAR1-/- mice and RNAs were extracted. Expression of CCL2, CCL7 and CCL12 was measured by RT-QPCR. The mRNA relative folds were determined by normalizing the level of each group to its GAPDH and then to WT infected mice (mean ± SEM; ns: no significant difference; ***P < 0.001). These data are a composite of three independent experiments (n = 6 mice per group). (B) Total leukocytes were isolated from PR8-infected WT, MyD88-/- or IFNAR1-/- mice and the cells were stained with anti-Gr1, -CD11b, -Ly6C and -CCR2 Abs. The percentage of Ly6ChighCCR2+ inflammatory monocytes in Gr1 + CD11b + gated cells is shown. This is a representative result of two repeated experiments with two-three mice per group. (C-D) Day 3 PR8-infected mice were treated either with isotype control antibody or anti-IFNAR1 blocking antibody. After 3 days, leukocytes were harvested and stained with anti-Gr1, -CD11b, -Ly6C and -CCR2 Abs. The percentage of Ly6ChighCCR2+ inflammatory monocytes in Gr1 + CD11b + gated cells and numbers of Ly6ChighCCR2+ inflammatory monocytes are shown (mean ± SEM; ***P < 0.001). These data are a composite of two independent experiments (Isotype control, n = 5; anti-IFNAR1 Ab treatment, n = 6).