Exploring the meaning of connectivity in the immune network.

It is suggested that the immune network possesses a distinct internal structure, such that B-lymphocyte clones fall into four categories: 1) A multi-affinity or "sticker" group A, containing all the immunoglobulins with auto-affinity, and generally having affinity for nearly all the other immunoglobulins; 2) and 3) Two "mirror" groups B and C, characterized by the fact that there is virtually no within-group affinity; the affinities between B and C can be arranged co-linearly so that a clone from group B has affinity with its opposite number(s) in group C; 4) A fourth group of low affinity, each clone having affinity only with clones from group A. Computer simulations show that this way of analyzing the connectivity of the network makes sense (a) in relation to the stereochemical origins of affinity; and (b) in relation to the dynamical behavior of the clones in a functioning network.