Respiratory tularemia is characterized by an absence of T_H1-type pro-inflammatory cytokines during early-phase of disease.

<p>(A) BMDMs (2.5×10⁵ cells/well) from wild-type (C57BL/6) mice and their mutant counterparts were infected with MHB-grown <i>Ft</i> LVS at a MOI of 100. Supernatants were collected after 24 h and analyzed for the presence of cytokines by CBA. ***<i>P</i><0.001. (B) Cell-free lung homogenates, BALF, and serum from C57BL/6 mice were recovered at 2 and 6 days p.i. following i.n. administration of 10³ CFU of <i>Ft</i> LVS and were analyzed for the presence of pro-inflammatory cytokines by ELISA. ***<i>P</i><0.001. (C) BMDMs (2.5×10⁵ cells/well) were incubated for 24 h with <i>Ft</i> isolated from mouse lungs at 2 and 6 days p.i. Supernatants were collected and analyzed for the presence of TNF by ELISA and compared to levels of TNF observed <i>in vivo</i> at the same point in time. ***<i>P</i><0.001, ns = not significant. All cell activation assays were conducted using a MOI of 100. Results represent the mean ± SEM from two independent experiments. (All results shown were subjected to One-way ANOVA with Bonferroni's Post-test).