Figure 3. Neutrophil recruitment following repeated SR exposures is primarily dependent on TLR2.

WT, TLR2^-/-, TLR9^-/-, and TLR2/9^-/- mice were exposed to SR 3 times / week for 3 weeks and analyzed 1 day after the last exposure. (A) BAL was performed and alveolitis determined using trypan blue dye exclusion. (B) Cells recovered from the BAL fluid were incubated with antibody to CD11b and Gr1 and analyzed by flow cytometry to determine the number of neutrophils (CD11b⁺/Gr1^high) in each group. (C) Expression of mRNA for cytokines was determined by qRT-PCR on RNA isolated from individual lung lobes (n = 3-5 mice per group) and is expressed as fold induction over WT unexposed mice. The data represent mean ± SD of duplicate samples and significance was determined using one-way ANOVA with Tukey’ post-hoc test (*p < 0.05 compared to WT SR exposed mice).