| Objective: To observe the shape and distribution of dendritic cells in the peripheral immune organs - spleen, and determine the change of these dendritic cells/antigen presenting cells and the related cytokines in immunodissonance in multiple organ dysfunction syndrome and the significance thereof. To enrich the study of trauma immunology and provide new theory for clinical study of MODS.Methods: 220 C57BL/6 mice, 6-8 weeks old, 20-25 gram, were randomly divided into normal control, 3 hour, 12-48 hour, 5-7 day, 10-12 day post trauma. MODS model were replicated by zymosan injection in the peritoneal cavity of the mice. The number of killed animals in each group is 30. 15 MODS cases resulting from severe trauma, burns, infections and sepsis were collected as MODS group. 16 cases including lienectomy after acute trauma and autopsy after sudden accidental death were collected as normal control group. The symptom, changes of body temperature, body weight and wet weight of spleen were observed in each group of the mice. Pathological changes of spleen were observed by light microscope and transmission electron microscope in both animal experiments and clinical groups. Apoptosis of spleen were also detected by means of TUNEL. Immunohistochemistry mark of CD205, CD86, S-100 and CDla were performed to observe their expression by DCs in spleen, so the change of distribution and content of DCs were detected in different group in mice and clinical cases; the expression of MHC-II antigen and IL-12p40 by DC/APC were also observed at the same time. T lymphocyte subgroup and I-Ab expression by DC/APC in peripheral blood were detected by flow cytometry. Changes of the level of IL-12p40 and IL-12p70 in serum and homogenate of spleen were detected by means of ELISA. Results: 1. Observation of normal spleen: In the spleen of normal mice andhuman, the distribution of DCs is mainly in the marginal zone and germinal center of the follicles, and scarcely in the white pulps and spleen cords. In mice, the content of DCs in spleen is about l-2%o, but in human it is about 3-4 %>. 2. Animal experiments: 3 hour post trauma, both body temperature and body weight of the experimental mice declined apparently. The area of white pulps became larger, and the lymphocytes are abundant. The number and the size of DCs increased markedly. The expression of CD205, CD86, I-Ab and IL-12p40 by DC/APC rose evidently. The expression of I-Ab by the mononuclear cells, the number of CD4 positive T lymphocytes and CD4/8 ratio declined in peripheral blood. The level of IL-12p40 increased, whereas the level of IL-12p70 decreased in serum and homogenate of spleen. 12-48 hour post trauma, body temperature and body weight of the experimental mice continued declining. The white pulps of spleen shrank, and the lymphocytes reduced, apoptosis of lymphocytes became obvious. The number of DCs in spleen was still plentiful, but the change of dissolution, degeneration and apoptosis appeared. The expression of CD205, CD86 and I-Ab by APC in the spleen declined, but IL-12p40 expression enhanced. The expression of I-Ab by the mononuclear cells and the number of CD4 positive T lymphocytes reduced, CD4/8 ratio declined markedly in peripheral blood. The level of IL-12p40 increased to the peak and the level of IL-12p70 decreased to the bottom in serum and homogenate of spleen. 5-7 day post trauma, body temperature and body weight of the experimental mice were close to normal value. The number of DCs diminished to normal level, apoptosis of lymphocyte alleviated. The expression of CD205, CD86 and IL-12p40 lowered, but I-Ab expression rose. The expression of I-Ab by the mononuclear cells, the number of CD4 positive T lymphocytes and CD4/8 ratio increased in peripheral blood. The level of IL-12p70 increased and the level of IL-12p40 decreased in serum and homogenate of spleen. 10-12 day post trauma, body temperature and body weight of the experimental mice declined remarkably. The white pulps and follicles of the spleen shrank or disappeared, and the lymphocytes became s... |
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