Adoptively transferred LPS-treated BMDCs effectively migrated to the lungs
The function of DCs is intimately associated with their capacity to migrate to target organs20. It was previously demonstrated that the onset of tolerance in DC10-treated asthmatic mice is progressive; thus, airway hyperresponsiveness (AHR) in mice is mildly attenuated at 2 weeks after transfer and vanishes entirely within 3 weeks4. To examine when and whether the injected DClps could successfully migrate to the lungs, we established a mouse model of asthma and treated asthma model mice with diverse DCs that were primed under different conditions. We used the fluorescent dye PHK26 as a marker for the trafficking of transferred DCs in vivo in treated mice, and mice were sacrificed on days 1, 3, and 7. One day after transfer, DClps labeled with PHK26 appeared in the lungs, with a modest proportion of the labeled cells (2.26%; absolute BMDCs is 396.). In contrast to DCia with 1.08% (144 cells total), saline control with 0.188% (35 cells total) (p<0.05). On day 3, the proportion of all DCs labeled with PHK26 peaked in the lungs, among which DClps increased the most markedly, representing 5.42% of the labelled BMDCs, compared to 1.52%, 0.98% in DCia and saline group (p<0.05). However, the number of DClps strikingly decreased on day 7 (0.628%, absolute cell number 82). No detectable difference was found among three groups (p>0.05).
These data indicate that DClps migrated to the lungs more effectively and gradually accumulated in the lungs within 1 week. Moreover, the decreased percentage of DClps in the lungs was consistent with the alleviation of lung inflammation in asthmatic mice, which further confirmed that DClps may effectively migrate to the lungs and take effect within 1 week.