No, passive immunity does not have memory.
Passive immunity provides immediate, but temporary, protection against a specific pathogen. This type of immunity is acquired when a person receives antibodies from an external source, rather than producing them through their own immune system. Because the body isn't actively involved in producing these antibodies, immunological memory is not established.
Here's a breakdown:
- How Passive Immunity Works: Ready-made antibodies are introduced into the body. These antibodies can neutralize pathogens or mark them for destruction.
- Lack of Immune Cell Activation: Passive immunity bypasses the normal processes of the immune system, such as B-cell and T-cell activation and proliferation. These cells are crucial for generating long-term immunity.
- No Memory Cell Formation: Because the body isn't actively fighting off an infection or responding to a vaccine, it doesn't produce memory cells (memory B cells and memory T cells). Memory cells are responsible for the rapid and robust response upon subsequent exposure to the same pathogen.
Therefore, while passive immunity offers immediate protection, it's not long-lasting. Once the introduced antibodies degrade, the individual becomes susceptible to the pathogen again unless they develop active immunity (through natural infection or vaccination).
Examples of Passive Immunity:
- Maternal Antibodies: A mother passes antibodies to her fetus through the placenta or to her infant through breast milk. This protects the baby for a short period after birth.
- Antibody Injections: In some situations, such as exposure to rabies or tetanus, a person may receive an injection of antibodies (immunoglobulin) to provide immediate protection.
In summary, passive immunity offers a temporary shield, but it does not equip the immune system with the ability to "remember" the pathogen and mount a faster, stronger response upon future encounters. This is the fundamental difference between passive and active immunity.
