Kinetic and distinct distribution of conventional dendritic cells in the early phase of lipopolysaccharide-induced acute lung injury.

Respiratory dendritic cells (DCs), especially conventional DCs (cDCs), are critically involved in the induction phase of the immune response in the respiratory system. However, little information concerning cDC kinetics in acute lung injury (ALI) is available. In this study, we have used a murine model of LPS-induced ALI to examine the kinetics and phenotype of respiratory, circulating and splenic cDCs. cDCs in the lung, blood, and spleen and the IL-6 level in the lung were detected at 6, 12 and 24 h after PBS or LPS challenge. In the ALI group, a rapid cDCs accumulation in the lung was observed, and there were highly significant correlations between the frequency of respiratory cDCs or the percentage of cDC expressing CD80 and the IL-6 concentration. However, the frequency of peripheral blood cDCs decreased rapidly in ALI mice, followed by a marked expansion. In addition, splenic cDCs only showed a transient expansion in ALI. cDCs within the blood, lungs and spleens had undergone a modest maturation in the ALI group. Our findings demonstrate that LPS-induced ALI provokes a dynamic and distinct distribution as well as phenotype changes in pulmonary, circulatory and splenic cDC populations. Lung cDCs may participate in the early inflammatory response to ALI.