Question

What role do memory cells play in our body?

Answer 1

Memory cells are specialised lymphocytes (B- and T-memory cells) produced during the primary immune response. They play a crucial role in immunity:

1. Persistence: They do not produce antibodies or kill infected cells, but remain in the lymph nodes for years, even decades, after the antigen has disappeared.
2. Rapid recognition: They carry receptors specific for the antigen encountered earlier and can recognise it immediately on re-exposure.
3. Secondary response: On the second or subsequent exposure to the same antigen, memory cells trigger a rapid and strong (heightened) secondary immune response which destroys the pathogen before the disease can develop.
4. Long-lasting immunity: Because of memory cells, one attack of a disease such as chickenpox or measles gives lifelong immunity, and vaccination becomes effective.
5. Basis of vaccination: Vaccination works by generating a large clone of memory cells in advance, so that the vaccinated person is protected when the actual pathogen attacks.

Memory cells give the immune system its remarkable 'memory' and are the basis of long-lasting protection against reinfection and of successful immunisation.