Study On The Dynamics Of Interaction Between Tumor Cells And Immune Cells

Based on the relevant knowledge of tumor biological immunotherapy and considering the effects of two types of immune cells on tumor inhibition,three dynamical models on the interaction between tumor cells and immune cells are established and analyzed.By using related theories of the dynamical systems,the immune effects of immune cells on tumor cells are explored,and some strategies that are beneficial to tumor treatment are sought.The main research contents are as follows.In the first chapter,the research background of this thesis from the perspective of tumor and tumor treatment are summarized,and the research development of tumor biological immunotherapy models and the main research contents of this thesis are briefly recounted.In the second chapter,factors such as the direct killing effect of effector T cells on tumor cells and the indirect immune effect of helper T cells by activating effector T cells by secreting class ? cytokines are considered.A dynamical model based on the interaction of tumor cells,effector T cells,helper T cells and class ? cytokines is studied.According to the different immune effects of the two immune cells,the system is divided into three cases: no immune case,single effect immune case and double immune case,and studied respectively.The existence conditions and stabilities of equilibria of the system are analyzed.It is found that tumor cells are in an unstable state and will proliferate in large numbers in the absence of immunity.In the case of single effector immunity,the stability of tumor cells depends on the immune strength of effector T cells to tumor cells and the loss of effector T cells in the process of immune response.In the dual immune state,the insufficient activation rate of helper T cells and the insufficient immune strength of effector T cells can lead to the continuous proliferation of tumor cells until the maximum capacity of the environment is reached and the tumor cells can be stabilized.When the excitation rate of helper T cells is large enough and the immune strength of effector T cells is appropriate,the tumor can be suppressed and reach a stable state.In the third chapter,a dynamical model of releasing class ? cytokines by helper T cells is studied.Stabilities of equilibria are studied in the system and it is found that tumor cells will continue to proliferate in the absence of immunity.During the immunization of helper T cells to the tumor,if the activation rate of the helper T cells is insufficient,the tumor cells will proliferate to the capacity of the environment and become stable.When the activation rate of helper T cells reaches a certain level,the proliferation of tumor can be effectively inhibited and an internal stable state can be reached.In the fourth chapter,a comprehensive immune model is established by considering the interaction between two kinds of immune cells,two kinds of cytokines and tumor cells in combination with the previous two chapters.From the perspective of time dimension,the model is reduced in dimension.It is found that the activation rate of tumor cells to helper T cells,the immune strength of effector T cells and the killing effect of ? cytokines on tumor play important roles in comprehensive immunotherapy.In the last chapter,the work content and research results of this thesis are summarized,and the biological significance and practical value of the dynamical models of the interaction between tumor cells and immune cells are briefly recounted.Finally,according to the shortcomings of the research work in this thesis,some problems and directions worthy of further study are put forward.