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Transforming growth factor beta (TGF-b)
is a mediator released by nearly all cell types. It has suppression activity on
the immune system, but exactly how this effect is carried out is not clear.
Previous experiments showed that IgG interacts with or carriers active TGF-b,
that could suppresses cytotoxic T-CELL responses to an immunogenic tumor in
mice. Since T cell RECEPTOR ((TCR)) has structural similarities with IgG, we asked
the question whether a specific (TCR) could interfere with and enhance the
suppressive effect of TGF-b
on T-CELL proliferation. T-CELL lines were established by limiting dilution and
specific (TCR) were extracted and purified. Mixed lymphocyte reaction (MLR) was
carried out using DA (RT1a) vs. LEW (RT11) lymph node
cells and DA vs. PVG (RT1u) lymph node cells. DA cells were used as
responder cells and PVG/LEW as stimulator cells. Proliferation of DA cells was
examined with different concentration of TGF-b
by adding 1mci
3H-thymidine 24 hours prior to harvesting the cells. The results
showed that the presence of a specific (TCR) does not have any effect on the
percentage of suppression when already fully suppressed by TGF-b.
However, it does have an effect on TGF-b
stimulated suppression under certain conditions. When (TCR) was added at the same
concentration as TGF-b
(1-2 ng/ml), inhibited TGF-b
stimulated suppression of proliferation, but when added at higher concentration
than TGF-b,
this effect disappeared, and the proliferation was suppressed in the same way,
as (TCR) was absent. Thus, (TCR) interaction with TGF-b
could play an important role in the homeostasis of immunity by augmenting the
proliferation of activated dominant lymphocyte clones. This would promote
suppression of activation/proliferation of new specific antigen-reactive clones
that may arise during ongoing immunity, and also suppressing some autoimmune
diseases