
Expansion of cytotoxic CD4 T cells in supercentenarians - corporate_shi11
https://www.pnas.org/content/early/2019/11/11/1907883116
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carbocation
Clonal expansion of hematopoietic precursors is something that we see
generally as people age [1]. Rather than positing a beneficial role for clonal
expansion of cytotoxic T cells, my null hypothesis would be that this clonal
expansion is simply another marker of aging.

1 =
[https://en.wikipedia.org/wiki/Clonal_hematopoiesis](https://en.wikipedia.org/wiki/Clonal_hematopoiesis)

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corporate_shi11
That disregards the possibility that certain clonal expansions could be
beneficial. General clonal expansion may be correlated with aging, but some
clonal expansion may concern extended longevity.

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carbocation
It doesn’t disregard that hypothesis. The hypothesis is interesting. But it’s
not my default hypothesis; it’s the alternative hypothesis.

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guytv
Can anyone explain in layman terms what this means? Does it mean that
supercentenarians' immune system posses a unique ability to kill cells?

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corporate_shi11
Yes, cytotoxicity is the ability to destroy cells. Most CD4 T cells are not
cytotoxic, regardless of the host's age. In the Supercentenarians studied
here, it was observed that the majority of their CD4 T cells were cytotoxic,
which is a very surprising result.

Having more cytotoxic CD4 T's could give the immune system better ability to
destroy invaders or cancer cells.

Even more surprising is that a large percentage of these mutant CD4 T's are
clonal, all traceable back to one individual (T cell) that mutated.

It's been shown that supercentenarians enjoy resistance to disease over their
entire lives. This research shows that may be due to their unique immune
systems.

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zingermc
With full knowledge I am being an armchair statistician, wouldn't it be
difficult to tell the difference between supercentenarians having
extraordinary resistance to disease and supercentenarians being the ones who
got lucky? Perhaps getting diseases is bad for your longevity!

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mannykannot
These are not mutually exclusive possibilities: "a large percentage of these
mutant CD4 T's are clonal, all traceable back to one individual (T cell) that
mutated."

