Immunology, particularly MHC restriction, aficionados:
While we were discussing MHC restriction in class, an interesting group
of student questions were posed. Something along the following lines:=20
"Somatic mutation does not occur in the TCR because it would be
detrimental to generate self-specific T-cells. Yet, we display
self-peptides in our MHC molecules. Why haven't we developed
mechanisms to display only foreign peptides? Also, if somatic mutation
can potentially lead to self-specific T-cells, shouldn't the same hold
with B-cells?"
Beyond the exceptions, I gave the canned answers that random mutation
of the TCR may change thymic-induced specificity leading to
autoreactivity; there are autoreactive B cells but T cells would
control them, polyclonal B-cell activation, etc. Your comments?
Also, what about the following, why not "=8Adisplay only foreign
peptides?" Teleological reasons could be given, possibility for
chronic activation, self-peptides used in thymic selection, etc. I
would be interested to hear other comments.
Thanks,
Klaus D. Elgert
Microbiology & Immunology Section
Biology Dept
Virginia Tech
