Auto-antibodies

[reising1]

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Question: A male with serum auto-antibodies that bind to the thyroid gland TSH receptors should be considered as:
Answer: having high levels of thyroid hormone because autoantibodies are overstimulating the thyroid gland.

Here are my questions
1. What are auto-antibodies? I thought they were responsible for distinguishing between "self" and "foreign"
2. Why do auto-antibodies stimulate the thyroid?
3. Why are antibodies even responsible for such a task? Antibodies are used in the immune system.
4. Do all "auto-antibodies" overstimulate glands? Is that their function or something?

 

[mcloaf]

1. Auto means "self". Autoantibodies are antibodies that aberrantly target parts of your own body, rather than foreign molecules. These are pathological and can cause autoimmune diseases.

2. In this case, they are stimulating the thyroid because they are binding to and activating the TSH receptor, mimicking the action of thyroid-stimulating hormone.

3. They aren't. See #1.

4. Not necessarily, it just depends on what protein they target.


http://en.wikipedia.org/wiki/Autoantibody

 

[reising1]

Okay, thanks. Apparently for this question we had to have the knowledge that auto-antibodies binding to the thyroid gland overstimulated the thyroid.

I'm thinking this kind of knowledge isn't needed for the MCAT. That's quite picky. (this was an examkrackers Bio question)