The Interaction Between Mouse Thymus And Heterologous Antigen Cells And Its Related Mechanisms

Thymus, as the central immune organ, is the main site of T lymphocyte development and maturity, and it plays a very important role in the control of autoimmune tolerance. Classical theory of immune tolerance considers that if the T cells encounter certain antigens in the development process, they will form a central immune tolerance to the antigens. Because if antigen into the thymus, it will be engulfed and antigen-presented by APC. It has been reported that allogeneic liver cells of intrathymic injected can survive for long in the recipient thymus, even to format hepatic lobule structure in the thymus. But in 1997, the report showed that the lifetime is limited for the intrathymic injected cells. And when the receptor immunized Inhibitors, the injected cells living time will be prolonged. These indicated that certain immune responses happened in thymus.Therefore, in this study, we initially explored the reaction occurred in mice thymus induced by intrathymic injection of A549 cells, and research the related mechanism in the process.In this experiment, we injected the A549 cells into mouse thymus, and then observe the thymus tissue histopathology at different time point after injection. In order for preliminary study of the fate of A549 cells in mouse thymus and the effects of thymic microenvironment caused by A549 cells. And then, we use the flow cytometry to analyze the changes of lymphocyte subsets in the mouse thymus, to analyze the immunity status of mouse thymus. At the same time, we injected the equal amount A549 cells into mouse spleen under the same conditions. And then analyzed the different fate of A549 cells in the thymus and spleen of mice.From the above research, we have obtained the following results:1. A549 cells cannot exist in the thymus for a long time. They will be killed and eliminated by immune cells, but the rate of removal is far inferior to that in spleen.2. Intrathymic injection of A549 cells make the proportion of CD4+T cells and CD8+T cells increased, while the ratio of CD4+/CD8+T cells decreased. And the intrasplenic injection of A549 cells make the CD4+T cells and the ratio of CD4+/CD8+ T cell increased.3. The intrathymic injection of A549 cells make the changes of thymus microenvironment. For example, the mechanical damage caused by injection and the ratio imbalance of the proportion of area of cortex and medulla and so on, but with the elimination of tumor cells, the thymus microenvironment gradually repaired and returned to normal.4. The intrathymic injection of A549 make the change of thymic T lymphocyte subsets proportion, which double positive T lymphocytes apoptosis, and the proportion of double negative and single positive cells increased relatively.From the above results, we have obtained the following conclusions:1. The interaction between the mouse thymus and the heterologous antigen cells will make the thymic microenvironment hurt, and the development and differentiation of the thymus cells have a certain effect.2. The same heterologous antigen cells, which were transplanted in the thymus or spleen, can induce rejection by lymphocyte mediated rejection; however, the immune effect occurs in the thymus, which is significantly different from that of the spleen.3. Studies showed that the mature lymphocytes in the thymus have the ability to recognize and respond to different antigens.The research of this paper is of great significance to the understanding of the thymus. The results of this study can provide some experimental evidence for the immune tolerance and organ transplantation or tumor immunity.