A systems approach to immunology

A tutorial overview of system analysis in the rapidly changing field of immunology is presented here. Many concepts which are well entrenched in engineering practice are shown to be relevant to immunology. For example, state-space analysis and a network topology arise naturally for the generation of lymphocytes (a class of white-blood cells) and in turn antibodies according to the clonal selection theory. Engineers embroiled in large-scale network problems may well appreciate immunological complexes whereby the humoral subsystem alone includes some 10 12 lymphocytes and 10 20 antibody molecules of 10 7 different chemical affinities in the immunologically unstimulated human body. Unfortunately, linear system theory, so significant in electrical networks, is shown to have limited application to immunology. On the other hand, coupled bilinear control systems and rate-limited processes arise due to the nature of cell division, differentiation, and chemical binding. Similarly, a chemical cascade of nonlinear amplifiers is generated as the complement subsystem for such purposes as tumor cell lysis. This controlled use of instability by means of parametric manipulation, which is so effective in disease control, may very well provide a clue for new design methodologies in engineering practice.