Figure 3.

Mucosal pre-exposure to Th17-inducing adjuvants mediates increased pathology after novel pandemic H1N1 influenza infection. A: C57BL/6 mice were mucosally exposed to 1 μg LT-IIb, 1 μg CT, or PBS. On day 3 after exposure, mice were infected with 1 × 10⁶ PFU of novel H1N1 influenza strain A/California/7/2009. Percentage weight change was determined in individual mice over time. B–D: FFPE lung sections were stained with H&E (B) or were assayed for CXCL9 mRNA localization (arrows) by in situ hybridization using a murine CXCL9 mRNA probe (C), and Gr1-accumulating neutrophils were detected by immunohistochemistry (D). E: The numbers of Gr1⁺ cells per ×20 field were counted. F: The levels of myeloperoxidase activity (MPO) were determined in lung homogenates. Data are expressed as means ± SD. n = 4 or 5 mice. ^∗P ≤ 0.05, ^†P ≤ 0.005, and ^‡P ≤ 0.0005. Original magnification: ×40 (B and C); ×200 (D).