Xenotransplantation - Nuffield Council on Bioethics
Xenotransplantation - Nuffield Council on Bioethics
Xenotransplantation - Nuffield Council on Bioethics
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Annex E : Glossary<br />
Annex E<br />
Glossary<br />
-gal (galactosyl -1,3-galactose)<br />
-gal is a sugar molecule found <strong>on</strong> the surface of pig cells. When pig organs are<br />
transplanted into human beings, -gal acts as an antigen. It is recognised by human<br />
antibodies and hyperacute rejecti<strong>on</strong> is triggered (paragraph 3.30).<br />
AIDS<br />
The disease AIDS (advanced immunodeficiency syndrome) is caused by the virus HIV<br />
(human immunodeficiency virus). The HIV virus infects a type of white blood cells<br />
called T-cells and destroys the cell-mediated immune resp<strong>on</strong>se, leaving the pers<strong>on</strong><br />
susceptible to lethal infecti<strong>on</strong>s. There is normally a latent period of several years<br />
between infecti<strong>on</strong> with HIV and <strong>on</strong>set of AIDS (paragraph 6.5)<br />
Antibodies<br />
Antibodies are protein molecules produced by a type of white blood cell called B-<br />
cells. Antibodies circulate in the blood and stick to foreign antigens <strong>on</strong> the cells of<br />
foreign organisms or of transplants. This may inactivate the foreign organisms or<br />
the transplant directly, or it may enable other white blood cells to destroy them.<br />
One important c<strong>on</strong>sequence of antibodies sticking to antigens is the activati<strong>on</strong> of a<br />
complicated reacti<strong>on</strong> called the complement reacti<strong>on</strong> (paragraphs 3.9 - 3.12)<br />
Antigen<br />
An antigen is a molecule found <strong>on</strong> the outside of a cell that is recognised as foreign<br />
by the immune system. Any infectious organisms entering the body, such as bacteria<br />
or viruses, have molecules called antigens <strong>on</strong> their surface. When the antigens are<br />
recognised as foreign, an immune resp<strong>on</strong>se is mounted to protect the body from<br />
infecti<strong>on</strong>. Unfortunately, an immune resp<strong>on</strong>se is also induced by transplantati<strong>on</strong>.<br />
This is because the cells of organs and tissues also have antigens <strong>on</strong> their surface<br />
(paragraph 3.10).<br />
Artificial organs<br />
A range of artificial organs and tissues are under development as alternatives to<br />
human organ transplantati<strong>on</strong>. These may be totally mechanical devices such as the<br />
artificial heart, or they may be bioengineered devices which combine living cells<br />
and artificial materials (paragraphs 2.11 - 2.31).<br />
Bacteria<br />
Bacteria are small single-celled infectious organisms. Many are harmless, but some<br />
cause diseases. For example, Mycobacterium tuberculosis causes tuberculosis.<br />
B-cells<br />
B-cells are the white blood cells that produce antibodies. Antibodies are an<br />
important element of the immune resp<strong>on</strong>se (paragraph 3.9 - 3.11).<br />
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