Memory to antigenic challenge of the immune system: synergy of idiotypic interactions and memory B cells.

Memory to antigenic challenge of the immune system is described as a synergy of two components: cycles of interacting B cells in a dynamic equilibrium which store an internal image of an antigen, and long-lived memory B cells which stabilize the cycle that generates them. Small cycles are most relevant to the immune system's memory. The network is globally stable and supports Jerne's idea that suppression is important. Our model allows for exponential increase of antigens during the initial stage of infection. It has a number of stable fixed points, viz the virgin state, the healthy immunized state, and a state of chronic infection, the last occurring if the antigen is virulent enough. Numerical simulations show a difference between primary and secondary response and exhibit both predator-prey and intracycle oscillations. In the case of a chronic infection, the simulations suggest a specific stimulation therapy triggered by repeatedly injecting the antigens, thus making the infection acute. An optimal therapy is indicated.