HIV and TCell Numbers/Memory

Jorg Kirberg kirberg at bii.ch
Wed Feb 22 10:14:23 EST 1995


In article <3idnvd$a3c at netnews.upenn.edu>, David Peritt
<Peritt_d at a1.mscf.upenn.edu> wrote:

> In article <Pine.3.89.9502211437.A132967-0100000 at UNCVX1.OIT.UNC.EDU> ,
> JAF at UNCVX1.OIT.UNC.EDU writes:
> >Lots of mouse data says the thymus functions well in adults.  Irradiated 
> >mice reconsituted with bone marrow become noramlly responsive pretty 
> >quickly, as do humans (about a year for people).  Thymectomized mice 
> >irradiated and bm reconsituted do not develope T cell funtion,  so the 
> >thymus must work even though it involutes.
> 
> The question is not whether the thymus is essential in BM Tx.  This is
> obviously true since the pre-T's must transverse the thymus to mature. 
> The question is if you Tx mature T cells into irr athymic mouse will
> these cells populate the mouse by proliferating to fill the T cell void?

If you transfer peripheral T cells serially from one nu to the next nu mouse
the expansion is enourmously. Actually it stops quite accurately when the
Hayflick number is reached.
Rocha, B., Dautigny, N., Pereira, P. (1989) Peripheral T lymphocytes :
expansion potential and homeostatic regulation of pool sizes and CD4/CD8
ratios in vivo. Eur.J.Immunol.  19, 905-911.
   
But, this expansion is antigen mediated:
Rocha, B., von Boehmer, H. (1991) Peripheral Selection of the T Cell
Repertoire. Science  251, 1225-1228.
   
It might be that many T cells are crossreactive enough to allow antigen specific
expansion up to the time they are anergic, exhaused or whatever ... thereby
creating the illusion that they could autonomously expand if there is enough
"room". If subsequently transferred to an antigen free host they actually
regain reactivity (can't find the reference now; also B. Rocha, probably last
year).
Altogether, as JAF at UNCVX1.OIT.UNC.EDU wrote, there is no need to postulate
T cell differentiation in an athymic individuum (of corse there is extrathymic
T cell differentiation, e.g. in the gut; but I think of standart ab T cells).
Rather, existing T cells are able to proliferate enormously.

jorg

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Joerg Kirberg                     EMAIL: kirberg at bii.ch
Basel Institute for Immunology    FAX:   41-61-605 13 72
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