Anergy & Memory

Kurt Schaudt olxsc01 at mailserv.zdv.uni-tuebingen.de
Tue Mar 22 09:58:16 EST 1994


Marcel Kuiper wrote:

>Hello immunonetters,
>
>Has anybody out there an idea about the question if anergized T-cells generate
>memory cells?
>
>The concept of anergy vs activation is quite difficult for me, since I
>think that anergized and activated T-cells against the same antigen might
>exist side by side. To me this seems to be a very inefficient and possibly
>dangerous for the organism, depending on which of both populations is
>dominant. The question whether anergized T-cells generate memory cells is
>central to me in this process, because anergy could then be equally impor-
>tant to activation in a 2nd response to an antigen.
>
>Marcel Kuiper. mkuiper at uk.ac.crc.hgmp        or    rchz103 at uk.ac.kcl.cc.bay

Induction of anergy must be seen as one step in a sequential process (of the
immune response); it is not induced at the start of an immune response.
When an immune response is started, its efficacy will depend on the time needed
for producing a sufficient amount of competent t cells (starting from theoretically
one cell!), meanwhile the target cells still will continue growing. This race can only
be won if cells of the immune system will grow much faster than the target cells, so
they must go through maximal stimulation (supplied by suitable interleukines
allowing the specific t cells to grow exponentially).
However, using this kind of maximal stimulation is most dangerous for the
organism and only reasonable if there exist effectual steps for extinguishing this
now needless growth when the fight is won (and the cells still are growing
exponentially).
This extinguishing can be (and is) reliably performed by apoptosis. But it would be
a pity to kill all the labourious produced t cells. Better, to keep a small percentage
alive but resting - for the next time!
And that is done by anergy. In our experience, in experiments inducing anergy
there is always a considerable percentage of cells lost by apoptosis. It seems that
in the mechanism of extinguishing the immune response a procedure is comprised
that ENSURES (seems to be not accidentally) a certain percentage of cells to
escape from apoptosis by getting anergic. 
Obviously in this extinguishing process the cytotoxic t cells must be involved, there
may be any mechanism enabling idle (because they find no target cell) CTL's to
stimulate other t cells (antigen specific) without appropriate costimulus and so
inducing apoptosis or anergy within them.
So far it is unclear how the decision apoptosis/anergy is made (I would like to hear
suggestions!).

Kurt Schaudt

Medical School of Tuebingen

Germany

kschaudt at mailserv.zdv.uni-tuebingen.de  



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