Effect of OVA or PBS aerosol exposure on the cellular composition of BM.

OVA-DC– or PBS-DC–immunized mice were challenged with either 1 ×, 3 ×, or 7 × daily OVA or PBS aerosols. At 24 hours after the last challenge, BM was collected and stained for Ly-6C and CD31. (A) Using this combination of markers, 6 distinct populations can be identified. Morphologically, these populations consist of: (a) 70% blast cells and 25% lymphoid cells; (b) lymphoid cells; (c) erythroid cells; (d) myeloid progenitors and plasmacytoid cells; (e) granulocytes; (f) 75% monocytes and 20% myeloid progenitors.19 Plots represent Ly-6C/CD31 staining on BM cells taken from mice exposed 7 times to PBS or OVA aerosol. There is a clear and selective increase in the CD31^hiLy-6C^neg subset in the OVA-DC/OVA group. Percentages of each population are indicated below the FACS plots. (B) Kinetics and magnitude of increase in the CD31^hiLy-6C^neg BM subset following OVA or PBS challenge (n = 6-8 per group per time point, * P < .05 compared with PBS-DC/PBS). Data are expressed as mean % DC precursors ± SEM. (C) Additional staining included CD11c and B220 to delineate plasmacytoid DCs. Plots were gated on CD31^hiLy-6C^hi cells (population d) in PBS-DC/PBS and OVA-DC/OVA mice. Average percentage of CD11c⁺ B220⁺ within the gate is indicated.