Internal images of antigens within the immune network.

The variable regions of antibody molecules react with each other via specific recognition of clonally distributed antigenic determinants, known under the general term of idiotypes. The totality of such interactions determines a special behavior of the immune system, as a whole, and its ability to regulate immune responses has been analyzed by the 'immune network theory' of Jerne [5]. In light of this theory, a particular property of idiotypes appears to be of special interest: as revealed by recent experiments, frequently idiotype-like determinants represent internal images of antigens. These internal images can be topochemical copies of nominal non-self antigenic determinants, of various functional non-lymphoid receptors, or of transplantation antigens. In this article, we present a view according to which internal images are essential structures which mediate cellular interactions leading to the selection and conservation of the immune repertoire of T and B lymphocytes. Our opinion is exposed in the context of experimental data obtained in several laboratories, including ours.