Figure 2. Nasal administration of MHV-1 remotely recruits Ly6C⁺ IMs into the lungs.

(A) Total cell numbers in the lungs after nasal-only MHV-1 infection. n = 3–7 per group, pooled from 2 independent experiments. No differences were observed. (B and C) Ly6C⁺CD11b⁺ cell infiltration in the lungs after nasal infection. Data in B are expressed as percentage of CD45⁺ cells. **P < 0.01 vs. dpi 0. Gating strategy is shown in C. n = 3–12, pooled from 3 different experiments. (D) Phenotypic analysis of Ly6C^hiCD11b⁺ cells. Blue lines represent the Ly6C^hiCD11b⁺ cells; red lines represent negative or positive controls in each small panel as indicated. Blue-filled represents F4/80 negative control. Ly6C^hiCD11b⁺ cells were Ly6G^–CD19^–CD3^-SiglecF^–NKp46^–F4/80^int. Neut, neutrophils; T, T cells; B, B cells; NK, NK cells; aM, alveolar macrophages. (E–G) Localization of Ly6C⁺ IMs in the lungs. BALB/c mice were intranasally infected with MHV-1 (10⁴ PFU in 2 μl MEM, 1 μl/nostril) or vehicle, and were then sacrificed at 2 dpi. The left lungs were clamped, and the right pulmonary vessels were then exclusively perfused via the right ventricle (E). The frequencies of Ly6C⁺ IMs in both left and right lungs were then analyzed and expressed as percentage of CD45⁺ singlet cells (F and G). **P < 0.01 vs. controls. n = 3 per group.