Inflammatory cell responses in bronchoalveolar lavage (BAL) fluid following RSV-RFP infection
Total BAL cell numbers were significantly elevated at 5 dpi returning to baseline by 7 dpi (Figure 2A), while macrophage numbers were significantly reduced at 3, 5 and 7 dpi, returning to baseline by 21 dpi (Figure 2B). Total numbers of neutrophils were significantly elevated at 3, 5 and 7 dpi and lymphocytes at 5 dpi, with both cell types returning to baseline by 21 dpi (Figure 2C and D).
Analysis of the percentage frequency of each cell type in BAL showed a similar significant trend as for absolute numbers (Figure 2C, E and G). This analysis showed a very high percentage of neutrophils in BAL; reaching close to 100% of all BAL cells at 3 and 5 dpi; then declining but still significantly raised at 7 dpi, remaining elevated but no longer significantly raised above baseline at 21 dpi (Figure 2E). Macrophage percentages decreased at 3, 5 and 7 dpi, returning to baseline by 21 dpi (Figure 2C). While the percentage of lymphocytes were elevated at 5 dpi, returning to baseline at 7 and 21 dpi (Figure 2G). Thus, RSV infection induced a significant inflammatory cell response in BAL at 3, 5 and 7 dpi that was dominated by neutrophils, which had returned to baseline by 21 dpi.