Network topology in immune system shape space

Abstract

We consider the emergent network topology of an immune system shape space at the end of primary response. We extend the formalism of shape space in order to model the relationship between activated immune lymphocytes and stimulant antigen presentation cells by way of a graph consisting of a pair G = (V, E) of sets. The vertex set V is the set of activated genotypes, while the edge set E connects such activated immune lymphocytes and stimulant antigen presentation cell in shape space. This paper shows how shape space graph edge weighting can be viewed, from the biological perspective, as the vigour with which an activated cytotoxic immune cell suppresses the infected antigen presentation cell which stimulated it. In this research, we also identify critical vertices (called α-vertices). These α-vertices act as bridging vertices in that they join subgraphs of unrelated immune response. As a consequence of this, such α-vertices ideally model immune cytotoxic lymphocyte memory cells. By representing memory cells as highly connected vertices, we show how such cells play a significant role in the elimination of pathogenic agents. © Springer-Verlag 2004.