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11/15/05 16:34:36 - Inflammation
Transplant rejection can usually be thought of as a basic problem with the recipient’s immune response, specifically their T-Cells. These blood cells, (so named because they mature in the thymus) have several roles in the immune response. Some just bump along looking for chemical signals given off by cells that have been attacked by invaders. Others look for anything that doesn’t belong, and others transmit information concerning the trespassers to the rest of the immune system so that the other cells can do their jobs. Still others attack infected cells to deny the disease any safe haven.
When we think of organ and tissue transplants, we usually worry about the recipient (or host) rejecting the transplant itself. This happens because the host’s T-cells identify the new tissue as being “foreign” and attack it. In GVHD, however, it’s the other way around. The host’s immune system has already been knocked out by the chemo, but the marrow stem cells introduced in the transplant are mixed with blood cells from the donor, including T-cells. Those are adult T-cells from the donor's body, so when they are introduced into new surroundings, they immediately realize that nothing here fits with what they're "used to". Thus, the graft begins attacking the host.
So, Aren’s situation is as follows: Aren’s immune system used to attack him, so we first suppressed it, then got rid of it and replaced it with a new one… which is now attacking him. So now, we're suppressing it, and... hmmmm...
Like I said earlier, though, this is still a pretty mild case. The doctors say that the trick will be to suppress the adult T-cells that came with the marrow long enough for them to die out. Once they’re dead, they’ll obviously not be able to attack anymore, but more importantly, they won’t be able to transmit the “knowledge” that Aren’s cells don’t belong to the new, immature T-cells.
I’m sure there’s some sort of parallel there. In a healthy immune system in a healthy person, T-cells detect foreign bodies and direct an appropriate response against them. Once they have identified them, they direct the surrounding tissues in their own defense mechanisms, which can include things like fevers and even inflammation. Like T-cells, we are usually good at hunting down problems and removing them from society. If an individual or group starts harming law and order, or even if it refuses to play by society’s rules, we descend upon them and neutralize them very quickly.
Sometimes, however, glitches appear in the system. Sometimes our societal immune system causes inflammation in areas that are not pathogenic. Sometimes we even are afflicted with a sort of autoimmune response against elements of society that are not only part of our own society, but vital to it. And sometimes the targets are actually elements of change that are absolutely vital to our survival. In fact, one could say that every major advance in human rights was seen as a disease. The American Revolution definitely was, as were the abolitionists in the early 1800’s. The labor movement of the early 1900’s was seen as a sort of infection until the Triangle Factory fire in 1911, and the civil rights activists of the 1960’s are still held in contempt by some elements of society.
Yet with all these examples of attempted rejection, we need to bear in mind that there definitely have been true sicknesses in the body of humanity: the fascist mindsets that led to both world wars, for example, not to mention the particularly lethal microbe known as Stalin.
So now we’re left with the question: which side are we on? Are we fighting a virus that will destroy mankind as we know it? Or are we trying to destroy a graft that may, in fact, change it forever but will allow it to continue to grow?
For more information on T-cells, click here
For more information on GVHD, click here
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Aren is undergoing a bone marrow transplant to fix the immune system defects that caused the loss of his little sister, Lily. To learn more, click here.
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