Long-term stability of diverse immunological memory.

Mathematical modelling is used to examine the effects of T cell apoptosis and memory differentiation dynamics on memory retention (memory stability). Apoptosis by cytokine deprivation induced death, and competition for survival signals are incorporated. Our models indicate that such population dependent processes are essential for the preservation of specific memory to previously encountered pathogens. Memory stability and vaccination properties improve significantly when population dependent mechanisms are present. These mechanisms work synergistically together to further improve memory characteristics. Our models emphasize the role of competitive cellular mechanisms in regulating repertoire structure and characteristics. Copyright 2001 Academic Press.