Hi guys, in this post I’ll talk about memory responses. Most of you probably know this already but I’ll go over it anyway. In response to an infection (or vaccination) that induces an adaptive immune response, some antigen-specific T and B lymphocytes differentiate to become memory cells. These cells can be found in blood, secondary lymphoid organs, bone marrows, tissues and divide very very very slowly. Should you get infected again by the same pathogen, these memory cells, which have already undergone activation, class switching and somatic hypermutation (in the case of B cells) divide very rapidly. The speed of the memory antigen-specific T and B cells division and activation is the reason why the infection is resolved very quickly compared to the primary infection.

Thus, much like memory in real life where we learn from our past experience which allows us to quickly respond to the present and future, immune cells also have memory.