• Question: why do our bodies push away cells that our not are own

    Asked by teddyhunter to Emma, James, Jayne, Kara, Sharon on 16 Mar 2011 in Categories: .
    • Photo: James Chan

      James Chan answered on 15 Mar 2011:

      Great question! This is our defence system. We have evolved to protect ourselves from harm and danger. In the natural world, there are all sorts of things that want to invade us, like bacteria, viruses, fungi, worms, ticks and so on, and in order to survive, we needed to develop a system to fight this. This is our immune system.

      The defence system is what gets kicked into action when you get a cold. The body is very clever in being able to recognise what cells are our own, and what aren’t, and it attacks foreign cells mercilessly and relentlessly until they’re gone. How does it do this? Well, all cells have markers on them which the white cells in your blood recognise. The white cells will recognise markers that are your own and markers that aren’t. When they find cells that are foreign, they attack by secreting toxic chemicals and mini-explosives (‘free radicals’), recruit other white cells and eat these things up. They are pretty hardcore cells. The product is often pus!

      Sometimes, the immune system gets it a bit wrong and starts attacking your own cells. This is the basis of what people call autoimmune disease, like rheumatoid arthritis, psoriasis and other diseases.

    • Photo: Sharon Sneddon

      Sharon Sneddon answered on 15 Mar 2011:

      The body is a eally clever thing, We have something called the immune system which basically protects our body from attack from infections and pathogens. Our immune system is made up from lots of differerent cells and proceses that all work to protect us. It’s made up from
      * Thymus
      * Spleen
      * Lymph system
      * Bone marrow
      * White blood cells
      * Antibodies
      * Complement system
      * Hormones

      If something is attacking our body, the immune system kicks into action. When antigens (foreign substances that invade the body) are detected, several types of cells work together to recognise them and respond. These cells trigger the B lymphocytes to produce antibodies, specialised proteins that lock onto specific antigens.

      Once produced, these antibodies continue to exist in a person’s body, so that if the same antigen is presented to the immune system again, the antibodies are already there to do their job. So if someone gets sick with a certain disease, like chickenpox, that person typically doesn’t get sick from it again.

      Although antibodies can recognise an antigen and lock onto it, they are not capable of destroying it without help. That’s the job of the T cells, which are part of the system that destroys antigens that have been tagged by antibodies or cells that have been infected or somehow changed. (Some T cells are actually called “killer cells.”) T cells also are involved in helping signal other cells (like phagocytes) to do their jobs.

      Antibodies can also activate a group of proteins called complement that are also part of the immune system. Complement assists in killing bacteria, viruses, or infected cells.
      hope that helps!

    • Photo: Emma King

      Emma King answered on 16 Mar 2011:

      Hi teddyhunter. Our bodies reject cells that are not our own because they are trying to protect us. The body is really really good at protecting us from outside things like bacteria and viruses – that’s why we get an immune reaction if we catch a cold or something. Our body fighting foreign things is what keeps us alive, but unfortunately it can be too good at it’s job, especially because it can’t recognise that a transplanted organ for instance is a good thing to have – it just sees it as something that is not it’s own and tries to destroy it.
      Hope that makes sense.

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