Modeling acquired immunity as an outcome of the interaction between host-related factors and potential antigen repertoires.

In an attempt to understand why different organisms defend against potential antigens differently, the influence of possible interactions between host-related factors and respective antigen repertoires on the complexity of host defense mechanisms was investigated. A compartmental model coupling these two variables was developed and tested. Data analysis suggests that the more complex the organism, the larger the size of its antigen repertoire. The two variables seem to advance in a parallel fashion suggesting that they could reach a state of equilibrium. Therefore, host-related factors may play a role in determining the size of the antigen repertoire on the one hand; on the other hand, increased antigen repertoire size may dictate the evolution of more complex mechanisms of immunity. Although the interplay between the two variables maintains some common themes in different groups of organisms, it results in clear differences pertinent to immunologic specificity, diversity, memory and self nonself discrimination.