In our immune system, how do the cells (whichever ones are appropriate) recognize and store the information of previous pathogens, and where in the body is that information stored?

Question

Follow up: Does that information deteriorate or do these cells ‘forget’?

Edit: If you’re able to answer the question, but can’t ELI5, then maybe explain in a way that a lay-person would understand i.e. not jargon-heavy.

In: Biology

Answer 1

In terms of “previous pathogens,” the memory of these pathogens are stored in B cells, specifically the “plasma” type of B cells. Plasma B cells were once regular B cells that were secreting antibodies specific to an antigen from an infection, vaccine etc, and once the infection subsides, the B cells matures into a plasma B cell. Plasma B cells are the quiescent forms of the B cell that are dormant in different tissues such as lymph nodes, spleen. Assuming that you had a sufficient immunologic response to that antigen (infection/vaccine), you would have many of these B cells (not exactly sure of the number but I guess in the hundred thousands?) and once the infection subsides, they lie dormant until it’s activated by a T cell that looks for that same antigen. This is why some vaccines require multiple doses to ensure that the body builds a sufficient immune response to create enough plasma B cells that will fight the future infection!

I am assuming that the definitions of antigen and antibody is known but if you don’t it’s fine! Antigen is any molecular compound that the body identifies it to be foreign. Antibodies are specific molecules that binds to specific antigens that “mark” it for destruction.