In article <v03130303b25292724ea4@[128.173.187.15]>,
Klaus D. Elgert <kdelgert at vt.edu> wrote:
>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.
>Somatic mutation of the TCR would also eliminate its specifity for self
MHC. If it doesn't recognize MHC, the peptide is inconsequential.
>>Thanks,
>>Klaus D. Elgert
>>Microbiology & Immunology Section
>>Biology Dept
>>Virginia Tech
>>>
--
Greg Maniero | Stars move with silent sounds.
University of Colorado | The universe is calm.
Dept of Environmental, Population, | Leaning on a staff, I climb
and Organismic Biology | up to the terrace.
