A Switching Memory Strategy in an Immune Network Model

Abstract

As an empirical knowledge on vaccination, it is known that immune memories against viral antigens (i.e., self-reproductive antigens) are sustained for a very long period more than 10 years, whereas against non-viral antigens, they are sustained only for a relatively short period less than a few years. This fact suggests that an immune system switches adaptability its memory strategy according to degree of antigen’s self-reproductive rate, its hazard rate. Therefore it is an interesting knowledge though, so far, a theory that indicates a causal relationship between durability of an immune memory and an antigen’s viral/non-viral character has not been clarified.

This study demonstrates why the durability of an immune memory depends on the viral/non-viral antigen character by taking a dynamical approach. Concretely, when an antigen increases its self-reproductive rate, the system changes at a critical self-reproductive rate, its memory strategy from a “forgettable” immune memory embedded in a transient dynamics to an “unforgettable” one done in a dynamical attractor.