Step-by-step explanation:
Immunological memory is the property of the immune system to store information about a stimulus so it can mount an effective response if it encounters the same stimulus again being this second response quicker and stronger even after years since the first encounter.
This kind of response is dependent on many subpopulations within T and B lymphocytes and NK cells. When encountering an antigen, B cells recognize it by membrane antibody specifically binding to the antigen and then being activated to expand rapidly with their progeny clones differentiating into plasma and memory B cells, these last ones have a long life span to remain in the body, ready when another encounter with the same stimulus occurs, this is how the basis for effective immunizations happens.
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