The body doesn't know.
Dogma is endogenous proteins from the cytosol go to the ER via TAP
load on class I
exogenous proteins are degraded in endosomes et al end up in MIIC and get
loaded onto class II.
Both there is considerable cross talk- i.e. cross presentation
Responses to the peptides are on the T cell side/ deletion/anergy/ignorance.
"chenhong" <chz155 at mail.usask.ca> wrote in message
news:2a79bee4.0208230837.4be34f19 at posting.google.com...
> Hi all,
>> I have a basic immunology question to consult: how does the body tell
> exogeneous peptides from endogeneous peptides.
>> I am guessing endogeneous peptides go through some modification
> process after they are synthesized. But if people know the structure
> and composition of an endogeneous peptide, then we can synthesize
> exactly such a peptide in vitro. Then how does the immune system tell
> where does this peptide come from. My second guess (wild) will be that
> the cell knows this by recalling if this peptide is swallowed or
> produced by itself.
>> As you can see, I need more professional people to help me out here.
> Thanks for any help you can give me.
>> Chenhong
