know as affinity maturation. Antibody Response 10 Plateau period lag perioc Exponential period 1 Decline 1015 20 30 35 Time(days） (Anamnestic response) 3 cells Primary 14 21 28 35 42 49 ime(deys) B cell precursors are derived from a stem cell.Through Ag-independent differentiation in a B cell environment,these cells acquire the competence to function a B cells.They migrate to secondary lymphoid organs,where they can differentiate into active B cells through ag-dep ndent differentiation.This leads to clones of plasma cells for each class of antibody.Memory cells can arise that will respond rapidly and more strongly upon subsequent encounter with same antigen. know as affinity maturation. B cell precursors are derived from a stem cell. Through Ag-independent differentiation in a B cell environment, these cells acquire the competence to function a B cells. They migrate to secondary lymphoid organs, where they can differentiate into active B cells through ag-dependent differentiation. This leads to clones of plasma cells for each class of antibody. Memory cells can arise that will respond rapidly and more strongly upon subsequent encounter with same antigen