Immunization and Aging: a Learning Process in the Immune Network
  The immune system can be thought as a complex network of different interacting elements. A cellular automaton, defined in shape-space, was recently shown to exhibit self-regulation and complex behavior and is, therefore, a good candidate to model the immune system. Using this model to simulate a real immune system we find good agreement with recent experiments on mice. The model exhibits the experimentally observed refractory behavior of the immune system under multiple antigen presentations as well as loss of its plasticity caused by aging. 
Rita Maria Zorzenon dos Santos (UFF, Niteroi-RJ, Brazil) and Americo   T. Bernardes (UFOP, Ouro Preto-MG, Brazil)