Innate immunity is non-specific type of defence, that is present at the time of birth. This is accomplished by providing different types of barriers to the entry of the foreign agents into our body.Acquired immunity, on the other hand, is pathogen specific. It is characterised by memory. This means that our body when it encounters a pathogen for the first time produces a response called primary response.When a host is exposed to antigens, which may be in the form of living or dead microbes or other proteins, antibodies are produced in the host body. This type of immunity is called active immunity. It is characterised by memory. This means that our body when it encounters a pathogen for the first time produces a response called primary response.

Which of following are memory cells ?

Both B-cells and T- cells.

 B cells, also called plasma cells, produce antibodies. Antibodies work as tags or alarms to target invading agents for destruction by other immune agents like macrophages. Memory B cells, like memory T cells, help the immune system respond more quickly to future invasions by the same agent.