Effect of OVA or PBS aerosol challenge on DC subsets within the draining mediastinal LN.

OVA-DC– or PBS-DC–immunized mice were challenged 3 times with either OVA or PBS aerosol. At 24 hours after the last challenge, mediastinal LN were collected, homogenized, and stained for the presence of MHCII⁺ CD11c⁺ DCs. (A) Within the MHCII⁺ population, CD11c⁺ cells were further characterized as CD11b⁺ myeloid and CD11b⁻ lymphoid DCs. (B) In OVA-DC/OVA animals, there is an absolute and relative increase in both lymphoid and myeloid DCs compared with PBS-DC/PBS mice (*P < .05). Data are expressed as mean number of cells ± SEM of 1 experiment representative of multiple experiments. (C) To investigate whether the observed increase in DCs in the LN was caused by enhanced migration, BM DCs were labeled with CFSE, and 2 × 10⁶ cells were injected intratracheally into mice without (PBS) or with (OVA) eosinophilic airway inflammation, and subsequently traced in the MLN and the inguinal nondraining LN. Injected DCs can be discriminated from endogenous DCs by CFSE positivity. Numbers represent the percentage of injected DCs of total cells in the LN.