Analysis of immune network dynamical system model with small number of degrees of freedom

We numerically study a dynamical system model of an idiotypic immune network with a small number of degrees of freedom. The model was originally introduced by Varela et.al., and describes antibodies interacting in a body in order to prepare for the invasion of external antigens. The main purpose of this paper is to investigate the direction of change in the network system when antigens invade it. We investigate three models, original model, a modified model and a modified model with a threshold of concentration over which each antibody can recognize other antibodies. In all these models, both chaotic and periodic states exist. In particular, we find peculiar states organized in the network, the clustering state.