Re: Is it true that the body canīt produce new antigenes (I mean completly new)

Dear Mikael:

Actually, there is a very important time when new antigens arise in your body: 
puberty.  During puberty, your body produces a whole new range of proteins (which 
can be antigens) that your own immune system has never seen before.  This fact 
raises an interesting question:  why don't people then become autoimmune at 
puberty?

Well, unfortunately, some people do, but why most people do not remains a 
mystery.  One thought is that these new antigens travel to the thymus, where they 
can be presented by antigen presenting cells there and participate in deletion of 
autoreactive thymocytes (so-called central tolerance).  Another thought is that 
when cells first enter the periphery (as the rest of the body is called) they may 
encounter these neoantigens and be tolerized rather than activated.  This could 
either happen because the antigens are presented in a noninflammatory state 
(there is no "danger signal" or inflammation going on as a basal state) and so 
the new T cells are tolerized and/or deleted, or that active suppression of 
potentially autoreactive T cells occurs.  

This is an interesting field of ongoing research in immunology-  why are we 
tolerant?  Why do some people lose tolerance to self?  I can't wait for the 
answers to these questions.

Have a great day!

Ingrid