The Role of Neutrophils during Mild and Severe Influenza Virus Infections of Mice
Figure 2
Neutrophil response in the airways after infection of mice with BJx109, HKx31 or PR8.
Groups of 5 mice were infected with 105 PFU of each virus via the intranasal route and at the times indicated, mice were killed and lavage performed. Numbers of (A) total BAL and nasal tissue cells, and (B) total BAL and nasal tissue neutrophils from virus-infected mice. Cell numbers in the BAL fluids from naïve mice are included for comparison. Neutrophils were identified by flow cytometry as CD45+ Gr-1high cells. A minimum of 50,000 living cells (PI−) were collected and analyzed from each mouse. * = BJx109 is significantly reduced compared to HKx31 and PR8; # = HKx31 is significantly reduced compared to PR8; x = HKx31 is significantly reduced compared to BJx109 and PR8 (p<0.05, one-way ANOVA). (C) Levels of KC, MIP-2 and MIP-1α in BAL supernatants at various times after influenza virus infection. Naïve (N) animals were included for comparison. Chemokine levels were determined by ELISA and results are expressed in pg/mL. The detection limit for each ELISA is indicated by the dotted line. ND = not done as all PR8-infected mice were euthanized at day 5 post-infection.