FIG. 2.

Kinetics of intrapulmonary IL-12 and IFN-γ induction during replicative L. pneumophila lung infection. A/J mice were inoculated with virulent L. pneumophila (10⁶ CFU/mouse). At specific time points p.i., the mice were euthanatized, and the lungs were excised. Total RNA was extracted, or the lungs were lavaged for collection of BALF. Transcript levels were quantified by real-time RT-PCR (IL-12p40 [a], IL-12p35 [b], and IFN-γ [c], while protein levels were quantified in BALF by cytokine-specific ELISA (IL-12p70 [d] and IFN-γ [e]). For mRNA quantification, PCR amplification of the housekeeping gene ubiquitin was performed for each sample to control for sample loading and to facilitate normalization between samples. The ubiquitin-normalized data was expressed as the fold induction of gene expression of L. pneumophila-infected mice compared to uninfected mice. Results represent fold induction of gene expression from six to eight mice per time point. For quantification of cytokines in BALF, results represent the means ± standard errors of the means of three to five animals per time point. ∗, P < 0.05 (considered significant).