FOOD ALLERGY: ANTIGENS AND ALLERGENS
Are antigens and allergens fundamentally different from each other? This is a question that causes a lot of confusion and it is worth spending some time looking at what these two words actually mean.
An antigen is any molecule that can provoke the body into producing antibodies to it. To do this the molecule must be above a certain size, because the B cells and their colleagues in the immune system are programmed to ignore very small molecules. So simple chemical molecules such as water or salt cannot act as antigens. However, some quite small molecules, that are too small to act as antigens on their own, may combine with proteins in the body, thus producing molecules that are large enough to be recognized by the immune system. Small molecules of this sort are called haptens.
Living organisms are composed of a great variety of chemical compounds, and some make more effective antigens than others. The important point about an antigen is that it should have at least one distinctive chemical structure on its surface – a chemical ‘handle’ that the antibody can grab hold of. This structure, which the antibody fecognizes, is called the epitope.
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Posted on April 20th, 2009 by admin
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