Among the features of real immune responses that occur when
antigens invade a body are two remarkable features.
One is that the number of antibodies produced in the secondary invasion
by identical antigens is more than 10 times larger
than in the primary invasion.
The other is that more effective antibodies, which
are produced by somatic hypermutation
during the immune response,
neutralize the antigens more quickly.
This phenomenon is called
In this paper, we try to reproduce these features by
dynamical system models and present possible
factors to realize them. Further, we present a model in which
the memory of the antigen invasion is realized without
immune memory cells.