Definition of POSITIVE SELECTION

Paul J Travers p_travers at icrf.icnet.uk
Wed Feb 2 09:51:58 EST 1994


Rick,
>  Have anergic T cells really
> been removed from the pool?  Or, can an anergic T cell be somehow
> "re-activated"?  

	my understanding of this point is that the state of anergy (if that is a
unique state) can be reset by replication, and that if you drive the
replication of "anergised" T cells eg with high levels of IL-2 then they
regain responsiveness.  Given time it appears this happens anyway, though
whether this represents random replication of the T cells I do not know.
	My caveat to the "state of anergy" is that there appears to be at least
two ways to induce nonresponsiveness in T cells, one the classical
jenkins/schwartz/ashwell (lack of costimulator) method and the other the
allen (suboptimal peptide) method.  From their Nature paper,
(Sloan-Lancaster et al - sorry can't remember the reference off the top of
my head), Paul Allen's method appeared to involve different signals and not
to be rescuable by exogenous costimulator.  Whether T cells rendered
nonresponsive by this latter method can recover, again I do not know.

	Paul
-- 
Paul J Travers                          phone : +44-(0)71-631-6262 (office)
ICRF Structural Biology Unit             "       "       "    6268 (lab)
Birkbeck College                          fax : +44-(0)71-436-8918
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London WC1E 7HX                         email :  p_travers at icrf.icnet.uk
England                                    or :  paul at histo.cryst.bbk.ac.uk



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