Self/nonself discrimination

Ken Frauwirth BioKen frauwirt at mendel.Berkeley.EDU
Fri Jul 29 13:23:04 EST 1994

In article <94210.085007FORSDYKE at QUCDN.QueensU.CA>, <FORSDYKE at QUCDN.QueensU.CA> writes: 
|>Disagree. Somewhere along the line, an antigen has to be labelled as
|>foreign. Consider CD4 and CD8 T cells separately. CD8 cells react with
|>MHC-peptides of intracellular origin. Most self-peptides will not be
|>displayed as part of intracellular self/not-self discrimination, so
|>"clonal ignorance" will predominate. A subset of intracellular self-
|>antigen-derived peptides will be displayed as a result of s/ns ic
|>discrimination, and deletion of the appropriate CD8 T cells will result.

I disagree with this.  As far as we can tell, all (or almost all)
self-antigens are presented on Class I MHC.  The cells do *not* 
distinguish between self and non-self.  In fact, allo responses are
probably due to recogniton of self antigens on foreign MHC (that is, self
antigens of the antigen presenting cells).  Self/non-self discriminaton
occurs in the thymus - most auto-reactive T cells are deleted (so self
antigens must be presented).  Since there are generally no non-self
antigens produced in the thymus (unless there is a viral infection or
tumor), *only* self-antigens are presented to T cells during development.
How could a cell recognize a "non-self" antigen (e.g. viral protein) that
was synthesized by its own ribosomes?

Ken Frauwirth (MiSTie #33025)  _           _
Univ. of Cal., Berkeley   .sig made under strict rabbinical supervision

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