How do lymphocytes become activated?
When any antigen binds to B lymphocyte , they produce two type of cells :
a. Plasma cells or effector cells which produces antibodies against the antigen.
b. Memory cells which stores the information about the antigen for future refrence.
If the same antigen enters the body again , memory cells will get activated bcoz they already had its knowledge before , hence immune response will be faster this time.