An immune system model for the generation of self-tolerance and memory

Abstract

To explain systematically the microscopic origins of two quite different response behaviors, immunological tolerance and the memory of the immune system, we proposed a model of the immune system in which we introduce a quantity “chronicity” which represents quantitatively the frequency of interaction of each immune cell with antigens. When the magnitude of the chronicity of an immune cell is too high or too low, the cell does not respond to the antigens. The cell may attack an antigen only when the magnitude of its chronicity is within a certain range. The activity of the system is also controlled by two kinds of cytokines, a positive cytokine which activates immune cells, and a negative cytokine which reduces the activity of immune cells. The system consists of immune cells, antigens, positive cytokines, and negative cytokines. The generation and destruction of these elements and the interactions between them are considered based on a cellular automations model. The model provides a unified view of the mechanism by which tolerance and memory are generated.