MHC restriction questions

MANIERO GREGORY maniero at stripe.Colorado.EDU
Tue Oct 20 16:41:25 EST 1998

In article <v03130303b25292724ea4@[]>,
Klaus D. Elgert <kdelgert at> 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.

>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.

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