Neutrophils drive LN lymphangiogenesis in the absence of B cells. (A) Increases in LEC populations in WT LNs were compared with μMT LNs for various points postimmunization. Increase is expressed as fold change over time-matched nonimmunized mice. (B) Immunofluorescence staining for LYVE-1 to visualize lymphatics in WT and μMT LNs. (C-D) Increases in neutrophils (C) and nongranulocytic myeloid populations (D) in WT and μMT LNs at various points postimmunization. Increase is expressed as fold change over time-matched nonimmunized mice. (E-F) Immunofluorescence staining of CD11b (E), Ly6G, and Gr-1 (F) expressing cells in WT and μMT LNs at day 14 postimmunization. (G-H) Increases in neutrophil and nongranulocytic myeloid (G) and LEC (H) populations within μMT LNs at day 14 postimmunization after NIMP-R14 or control rat IgG treatment. Increase is expressed as fold change over nonimmunized mice. (I) Percentage of BrdU⁺ proliferating LECs within μMT LNs after NIMP-R14 or control rat IgG treatment. Data from panels A, C, and D are pooled from 3 independent experiments with 4 to 5 mice per group in each experiment (n = 12-15). *P < .05 (between immunized WT and μMT LNs at the same point). Data from panels G and H are pooled from 2 independent experiments with 4 to 5 mice per group in each experiment (n = 8-10). Data from panel I consist of 8 mice per group (n = 8). Bars represent mean ± SD. *P < .05; **P < .01. Images from panels B, E, and F are representative of 4 independent experiments (n = 4). Scale bars in panel B represent 400 μm for control and 200 μm for immunized LNs, respectively. Scale bars represent 100 μm in panel E and 200 μm in panel F.