158 Molecular Mimicry (2)

It appears that the immune system can attack cells in various parts of the body. The results are sometimes very serious so it would be good to know why this happens to some people.


Last time we mentioned that each unwanted virus or bacteria that enters the body is attacked by the immune system in order to keep us safe from those invaders. We want that to happen. Our immune system knows the difference between an invader and our own cells. But in some people the cells that are similar to invaders are attacked along with the invaders. Hmmm… so, in some people, when the cells are similar it is possible for the immune system to make this error. This is called “molecular mimicry”.


Molecular mimicry? What exactly is that? A protein molecule that enters our body and is identified as “foreign” (in other words something that should not be there) is called an antigen (another fancy word). But the response of our immune system is to create an antibody for each type of antigen that it finds so that the antigen is rendered harmless. (Did you understand that? To put it simply, for every invader (antigen) our body produces an antibody to fight it off.) This is a very good plan but as we said, a molecule in our body that is very similar can be attacked along with these “foreign” invaders. What is more unfortunate is that parts of proteins in some foods and infectious agents resemble parts of various proteins in our body. Oh, no!!


So… molecular mimicry can explain why the immune system attacks itself in some people. It is really a case of mistaken identity in which the immune system (in certain susceptible people) mistakes part of the body for a foreign invader. My goodness… if there is a way to escape this we need to know about it.


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