With repeated exposures to the same antigen, a host will produce antibodies of successively greater affinities.
Affinity maturation primarily occurs on membrane immunoglobulin of germinal center B cells and as a direct result of somatic hypermutation (SHM) and selection by TFH cells.
[1] The process is thought to involve two interrelated processes, occurring in the germinal centers of the secondary lymphoid organs: Like the natural prototype, the in vitro affinity maturation is based on the principles of mutation and selection.
Random mutations inside the CDRs are introduced using radiation, chemical mutagens or error-prone PCR.
In addition, the genetic diversity can be increased by chain shuffling.