Evolution of specificity in an immune network.
A dynamic antigen response of the immune network is discussed, based on shape-space modelling. The present model extends the shape-space modelling by introducing the evolution of specificity of idiotypes. When the amount of external antigen increases, a measure of stability of the immune network is lost and thus the network can respond to the antigen. It is shown that specific and non-specific responses emerge as a function of antigen amounts. A specific response is observed with a fixed-point attractor, and a non-specific response is observed with a chaotic attractor for the lymphocyte population dynamics. The network topology also changes between fixed-point and chaotic attractors. For some antigen amounts, chaotic attractors will vanish or become long-lived super-transient states. A dynamic bell-shaped response function will thus emerge. The relevance of long-lived chaotic transient states embedded in fixed-point attractors is discussed with respect to immune functions.
Harada
K
K
The Graduate School of Arts and Sciences, Institute of Physics, University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo, 153, Japan. harada@sacral.c.u-tokyo.ac.jp
Ikegami
T
T
D000818:Animals; D000915:Antibody Affinity; D000918:Antibody Specificity / Q000276:immunology*; D000941:Antigens / Q000008:administration & dosage; D004306:Dose-Response Relationship, Immunologic; D019143:Evolution, Molecular; D006801:Humans; D007130:Immunoglobulin Idiotypes / Q000276:immunology; D018448:Models, Immunological; D017711:Nonlinear Dynamics
D000941:Antigens; D007130:Immunoglobulin Idiotypes