Figure 3.

Early ablation of CD169⁺ cells leads to enhanced morbidity without enhancing circulating effector CD8 T cell responses. (A–C) Naïve Wt littermates or CD169-DTR mice were treated with DTx then euthanized 4 days later. (A) CD64 positive and negative compartments were assessed by flow cytometry. (B) CD169 expression in CD64 positive and negative cells from the lung were measured by flow cytometry and compared to a fluorescent-minus-once (Fmo) control for CD169 antibody specificity (top). CD64⁺ cells were classified as AM (Siglec-F^Hi CD11b^int) or iM (Siglec-F^Lo CD11b^Hi) (B, bottom). (C) Lung resident (R, CD45⁻ i.v.) and circulating (C, CD45⁺ i.v.) alveolar macrophages (AM) inflammatory macrophages (iM), monocytes (MNC), and neutrophils were quantitated by flow cytometry. (D–F) Wt littermates or CD169-DTR mice were treated with DTx then infected with influenza PR8. (D) Lung myeloid cell populations were quantified by flow cytometry at day 3 post-infection. (E) Percentage of initial body weight was measured daily for 14 days post-infection (p.i.). (F) Percentage of CD4 and CD8 T cells (left) or % of D^b-NP-specific CD8 T cells from blood PBMCs 10 days post-infection. ^*p < 0.05 for CD169-DTR compared to wt. Data are representative of 2–3 experimental replicates except (A–C).