Figure 2.

Dendritic cells (DCs) are the cardinal contributors of the transport of antigen to lymph nodes. (A,B) C57BL/6 mice were infected intravenously (i.v.) with 200 plaque-forming units (PFUs) of lymphocytic choriomeningitis virus strain WE (LCMV-WE). Immunofluorescent sections of spleen were stained for (A) LCMV nucleoprotein (LCMV-NP; green), CD169⁺ macrophages (CD169; red), and B cells (B220; blue) on day 3 after infection or for (B) LCMV-NP (green), DCs (CD11c; red), and B cells (B220; blue) on day 5 (d5) after infection. Scale bars represent 100 µm (n = 3). Fluorescence images were captured at 20× magnification with a Keyence BZ-9000E microscope. One of the three representative images is shown. (C) C57BL/6 mice were infected i.v. with 2 × 10⁶ PFU LCMV-WE. Virus-positive DCs were measured in spleen tissue on day 3 after infection by fluorescence-activated cell sorting (n = 5, from one experiment). Black squares = naive; white squares = LCMV. (D) CD169-diphtheria toxin receptor (DTR) and littermate control mice were treated with diphtheria toxin [30 µg/kg body weight (bw)] on days −3, 0, 1, and 2. On day 0, mice were infected with 200 PFU LCMV-WE. Viral titers were measured in the spleen and iLNs on d3 after infection (n = 6, pooled from two experiments). Black squares = wild type (WT); white squares = CD169-DTR. (E) CD11c-DTR and littermate control mice (WT) were treated daily with diphtheria toxin (15 µg/kg bw) from day 0 until day 2. On day 0, mice were infected with 2 × 10⁶ PFU LCMV-WE. Viral titers were measured in the spleen and inguinal lymph nodes (iLNs) on d3 after infection (n = 8, pooled from two experiments). Black squares = WT; white squares = CD11c-DTR. Statistical significance was set at the level of P < 0.05 and was determined by Student’s t-test (C–E). n.s., not significant; **P < 0.01, ***P < 0.001.