Objective To investigate the kinetics and phenotype of spleen dendritic cells (DC) in lipopolysaccharide (LPS)-induced acute lung injury (ALI) mice.Methods Thirty-six C57BL/6 mice were randomly (random number) divided into two groups:control group and ALI group.Spleens were harvested at the following intervals of 6,12,and 24 h after LPS or PBS administration.Lung wet weight / body weight ratio (LW/BW) was recorded to assess lung injury.Meanwhile,pathological changes were examined under optical microscope.The IL-6 level in the lung was measured by using ELISA (enzymelinked immuno sorbent assay).The DC in the spleen was measured by flow cytometry (FCM).Results (1) LPS-ALI resulted in a significant increase in LW/BW ratio.(2) Histologically,extensive alveolar wall thickening resulted from edema,severe hemorrhage in the interstitium and alveolus,and marked and diffuse interstitial infiltration with inflammatory cells were observed in the ALI group.(3) Meanwhile,the levels of IL-6 in lung tissue were significantly increased in the LPS-induced ALI mice.(4) LPS-induced ALI led to divergent kinetics of spleen DC in ALI mice.In ALI mice,spleen DC only showed a transient increase at 12 h.(5) All DC within spleens had a modest maturation in ALI mice.Conclusions LPS-induced ALI provokes a transient increase as well as modest maturation of spleen DC.

Objective To observe the expression of I-Ab/I-E on circulating,lung and splenic dendritic cells (DC) in acute lung injury (ALI) mice.Methods Twenty-four C57BL/6 mice were randomly divided into four groups:control group,ALI 6 h,ALI 12 h and ALI 24 h group.Blood,lungs and spleens were harvested after lipopolysaccharide or phosphate butter solution administration.The expression of I-Ab/I-E on DC was assessed by flow cytometry (FCM).IL-6 level in the lung was measured by enzymelinked immunosorbent assay (ELISA).Lung wet weight/body weight (LW/BW) was recorded to assess lung injury.Meanwhile,pathological changes were examined under optical microscope.Results (1) lipopolysac charide-induced ALI mice resulted in a significant increase in lung LW/BW ratio.(2) Histologically,widespread alveolar wall thickening caused by edema,marked and diffuse interstitial infiltration with inflammatory cells,and severe hemorrhage in the interstitium and alveolus were observed in the ALI groups.(3) The level of IL-6 in lung tissue was significantly enhanced in ALI mice.(4) FCM analysis showed that I-Ab/I-E expressions on lung DC [(73 ±9)％],and splenic DC [(81 ±8)％] were significantly higher than that on circulating DC [(24 ± 7) ％ ; P ＜ 0.05] in control mice.(5) In ALI mice,the expressions of I-Ab/I-E on peripheral blood DC were (34 ± 17)％ at 6 h,(51 ± 16)％ at 12 h,(50 ± 17)％ at24 h respectively; I-Ab/I-E expressions on lung DC were (82 ± 14)％ at 6 h,(88 ±6)％ at 12 h,(90 ±10)％ at 24 h respectively; the expressions of I-Ab/I-E on splenic DC were (88 ± 8)％ at 6 h,(89 ± 4)％ at 12 h,(93 ± 9)％ at 24 h respectively,which were also significantly higher than those on the peripheral blood DC (P ＜ 0.05).(6) The I-Ab/I-E expressions on circulating DC in ALl mice at 12 h and 24 h was significantly higher than that on circulating DC in control mice (P ＜ 0.05).(7) The I-Ab/I-Eexpressions on lung DC and splenic DC in ALI mice at 24 h were significantly higher than those on lung DC and splenic DC in control mice (P ＜ 0.05).(8) There was a significant correlation of I-Ab/I-E expression on respiratory DC with the IL-6 level and lung injury score in LPS-induced ALI group (P ＜ 0.05).Conclusions There is a dynamic characteristic in the expression I-Ab/I-E on circulating,lung and splenic DC populations in ALI mice.I-Ab/I-E on pulmonary DC seems to play an important role in the pathogenesis of ALI.