Figure 5

Pro-inflamatory and lymphocytic cytokines. The concentration of several pro-inflamatory and lymphocytic cytokines was determined in the supernatants of lung homogenates. IL-12_p70 (NK and CD4 T-cell stimulant) was produced earlier and at significantly higher levels in adult mice (black circles) (A), which correlated with an earlier detection of IFN-γ in adult animals. IL-1β concentrations peaked at day 5 post-infection in adult mice (black circle), but steadily increased in aged mice (B). TNF-α and IL-1α concentrations increased similarly in both adult and aged mice until day 5 and then declined over the 19 days of observation in adult animals (black circles)(C and D). In contrast, these two cytokines continued to increase in aged mice (white squares) with significantly higher concentrations at day 7-9 post-infection (C and D). The lymphocytic cytokines, IFN-γ and IL-6, spiked earlier in adult mice (black circles) (E and F). The graphs represent cumulative results of two different experiments. The arithmetic mean (± SEM) of the cytokine(s) concentration of 4-6 mice assayed at each time point was plotted. Stars indicate statistical difference between aged and naïve animals.*P < 0.05. **P < 0.01. ***P < 0.001.