In the case of certain diseases like mumps, measles and chicken pox, the secondary immune response gives a life long immunity. Give the scientific reason behind this.

Explanation

Our body produces the T-lymphocytes against the antigen i.e., chicken pox causing agent and they attack and destroy the antigen. Some of the T-cells get differentiated into memory T-cells. These cells are stored in the lymph nodes and spleen. They recognise and produce antibodies when the same attack the body a second time. This is a very rapid process. Memory T-cells have a long life. These cells are responsible for the life long immunity to certain diseases like chicken pox, measles and mumps.