Some Thoughts on the Ontogenesis in B-Cell Immune Networks

Abstract

In this paper we focus on the antigen-independent maturation of B-cells and, via statistical mechanics tools, we study the emergence of self/non-self discrimination by mature B lymphocytes. We consider only B lymphocytes: despite this is an oversimplification, it may help to highlight the role of B-B interactions otherwise shadowed by other mechanisms due to helper T-cell signalling. Within a framework for B-cell interactions recently introduced, we impose that, during ontogenesis, those lymphocytes, which strongly react with a previously stored set of antigens assumed as “self”, are killed. Hence, via numerical simulations we find that the resulting system of mature lymphocytes, i.e. those which have survived, shows anergy with respect to self-antigens, even in its mature life, that it to say, the learning process at ontogenesis develops a stable memory in the network. Moreover, when self-antigen are not assumed as purely random objects, which is a too strong simplification, but rather they are extracted from a biased probability distribution, mature lymphocytes displaying a higher weighted connectivity are also more affine with the set of self-antigens, ultimately conferring strong numerical evidence to the first postulate of autopoietic theories (e.g. Varela and Counthino approaches), according to which the most connected nodes in the idiotypic network are those self-directed.