T-cells populations when thymus non-functional

Macintosh User CDH8 at le.ac.uk
Tue Oct 19 15:40:15 EST 1999

In article <3805A85F.41E08DA0 at pharma.u-strasbg.fr>, "paul.fonteneau"
<fonteno at pharma.u-strasbg.fr> wrote:

> vborde at my-deja.com wrote:
> > 
> > Hello everyone
> > I would like to know what would happen to the
> > T-cells population (repertoire) when the thymus
> > becomes non-functional, at the adult phase? Would
> > this person lose all his mature T-cells? Would he
> > also lose his self tolerance and become velnerable
> > to autoimmune disease? How are the T-cells
> > renewed? Thank you very much.
> It's probably the subject of the next Nobel's prize ;=))
> In fact, nobody knows what happens in this case.
> It seems that some mature, educated T-cells could survive for a very
> long time in the periphery.
> Another hypothesis says that they could have the ability of
> self-renewing... 
> The last hypothesis explains that may be there is another place for
> T-cells to be educated (skin ? epithelia ??)
> But all the observations which are made show that older persons are more
> sensitive to autoimmune disease...

Some interesting points, but I was under the impression that from a recent
set of both Nature/science and a recent J.ex.med paper that the thymus is
not non-functional it continues to produce mature T-cells and NK cells. 
there is however a slight bias towards Th2 I think.  In old age the thymus
involutes but does not stop T cell development.  Yes the gut epithelium
does help in CD8 Single positive and the CD3+/CD4-/CD8- subset in both
neonatal and adults though this has been predominatly in rodents and

There was an indication that mature T-cells may re-enter the thymus and
help in negative selection.  It was a swiss/German group I think (Boehmer
et al maybe).



Immunotoxicology section.

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