Characterization of the myeloid compartment in PbA-infected B6, BXH2, [BXH2×B6]F1 hybrids and <i>Irf1^−/−</i>.

<p>Spleens from B6, BXH2, [BXH2×B6]F1 and IRF1^−/− mice were harvested prior to or six days following PbA infection, and processed by flow cytometry. 2×10⁶ splenocytes were stained with CD45, CD11b, Ly6C, Ly6G, F4/80, CD11c and MHCII, and representative cellular profiles are shown for each strain (A). The numbers within contour plots refer to gates R1 (monocytes) or R2 (granulocytes) and are reported as mean ± SD (gated as percentages of CD45⁺ cells). Absolute numbers of day 6 PbA-infected mice are shown for (B) CD11b⁺Ly6G⁺ and (C) CD11b⁺F4/80⁺ populations, indicating an expansion of the myeloid lineage in the BXH2 strain, compared to B6, [BXH2×B6]F1 and IRF1^−/− animals. Reduced numbers of myeloid dendritic cells (D) along with lower serum IL12p40 levels (E) are noted in ECM-resistant BXH2 and [BXH2×B6]F1 compared to ECM-susceptible B6 mice. (F) Levels of secreted IL12p40 were determined in culture supernatants from splenocytes of infected mice. Dashed gray line represents IL12p40 detection limit. Differences were considered significant when p<0.05 and calculated compared to the B6 strain (Student's t-test: *p<0.05, **p<0.01, ***p<0.001).