• Question: How do memory cells work in the immune system, does the nucleus store information?

    Asked by cslayer11 to Alex, Jools, Lynz, Matt, Rika on 20 Jun 2011.
    • Photo: Julie Greensmith

      Julie Greensmith answered on 15 Jun 2011:

      I did some work in a lab on this a couple of years ago – the truth is we dont really know how memory cells work. There are lots of theories, but strangely we can actually find “memory cells”. We think that they might be cells that keep being activated by the same invader (bacteria or virus). We think that they may pass on this information to daughter cells when the cell reproduces and so the body gets a memory of the bad stuff.. But no, we dont think that this is stored in the nucleus, but is done by making the cell produce a low level of certain chemicals over its life and telling other cells about it too.

      However, remember, thats just a theory! We have not proved it yet!!

    • Photo: Alex Davenport

      Alex Davenport answered on 20 Jun 2011:

      Wow, that is a really good question! Ok so there are two main types of memory cell, The memory T cell and the memory B cell.
      memBcells are B cells that produce antibody to epiptopes (signature sequences) of pathogens that the body has been infect with before. They come about from a previous infection. The B cell population specific for the epitope is clonally expanded by the immune system and these are then used to produce a large quantity of specific antibody against the infection. As they are B cells they also under a process known as somatic hypermutation. All that means is the genes inside the nucleus rearranges for parts of the antibody. So that it can change it’s type of antibody and its specificity. Anitbodies that are more specific for the pathogen are selected whilst other are die out or are deactivated. These cells are then also clonally expanded and produce a HUGE quanitity of antibody to help clear the infection. Most of these cells will die but a few will remain and will continue to express the specific antibody for the pathogen so that when the body is re-infected it can mount a quicker and stronger response. Repeat exposures can also increase the number of specific sequences the immune system as a whole can see and can help clear the infection quickly.
      Now without getting too overly complicated, what happens is when then the cells are activated and clonally expand (Both T and B cells) they fight the infection. Most of these cells then die and memory cells are thought to be formed in low numbers. These are continuously exposed to cytokines (chemicals that cells produce) and they are then ready and primed so that when the infection happens again, they can be reactivated in a quicker response. A normal naïve adaptive response can take 72 hours, whereas a memory cells response is much quicker!

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