| Objective Bacterial translocation (BT) after trauma is major cause of sepsis and multiple organs dysfunction syndrome (MODS),which can result in high morbidity and mortality in trauma patients. The mechanism of BT is still unclear. Inflammatory stimulations can lead to migration and morphological changes in peripheral dendritic cells (DCs). Dendritic cell is now known as the most powerful antign presenting cell (APC). We presume that the intestinal DC will undergo the same process after hemorrhagic shock. To test our hypothesis,we observed DC changes on morphology and function after trauma,and its expression of MHC class II. We tried to find out the role of DC in bacterial translocation after truma and the change of its atigen presenting ability in bacterial translocation.Methods Adult Wistar rats were randomly divided into two groups:sham or hemorrhagic shock Sham treated rats did not undergo hemorrhagic shock,while shock rats were made shock by drawing blood via carotid artery with 5.3kPa of mean arterial blood pressure. One hour after treatment,shock rats were then resuscitated with shed blood and same volume of Ringer's solution. Using sterile techniques,mesenteric lymph nodes (MLNs) were harvested at 12 hours after resuscitation. DCs were freshly isolated by density gradient centrifugation and panning. After pulification,mouse anti rat OX-6 FITC monoclone antibody was labeled. The expression of MHC-II on MLN DCs were detected and analized by flow cetometry.Results The amounts of DC in MLNs varied in different interval,they reached to the maximum value at 12 hours after hemorrhagic shock. DCswere separated from MLNs and evaluated by stained with S-100 protein. The viability of DCs dissociated from MLNs reached to 96.10% at highest level. In sham-operated group,DC's distribution was dispersed,and morphologically elliptical,lack of branches. DC in hemorrhagic groups stock out abundant branches,which held T cells tightly.Being labeled OX-6 FITC mAb,dissociated cells were analysed by flow cytometer. Cytofiuorometric analysis showed that DCs from shock group express high level of MHC class II . However,DCs from sham-operated group did express MHC class II antigens but at much lower level. The class II MHC expression reached to 98.12% in max level at 12 hours after trauma. There are linear relationship between MHC- II expression and DC migration (r=0.77,p<0.01) . The ability to stimulate MLR response,as we found,DCs in hemorrhagic group show more activity contrasted to those in sham-operated group.Conclusions Hemorrhagic shock can result in morphological and functional transformations of gut DCs,the number of DCs is positively related with the amount of bacteria in MLN. It is reasonable to postulate based on our findings that DC may work as an important bacteria carrier during the generation of BT,just as macrophages,which had been validated by many convincing experiments before. MHC-II is a very important surface marker which keeps importent relationship with the ability of antigen presenting. Mature DC express high level MHC-II distinguished with immature DCs. We found that the amouts of DCs from shock groups keep coincident relationship with it's the expression of MHC- II. Then we may draw a conclusion that the route of DCs immigration is just the route of bacterial translocation. It may be the beginning of enterogenic infection in trauma-homological shock. Dissociation of DCs from tissues and the researchs of DCs' functions in tumor immunology or organ transplantation have now been proved an attractive prospect in clinical application. |
PDF Full Text Request