exercise immunology

Richard Aaron Warnock erawtech at leland.Stanford.EDU
Fri Feb 2 16:51:54 EST 1996

In article <Pine.SOL.3.91.960201095947.4160A-100000 at student.canberra.edu.au>,
Zulu / Fales Bernadette  <u931505 at STUDENT.CANBERRA.EDU.AU> wrote:
>Dear netters
>It has been reported in the literature that during exercise, there is an 
>increase in the number of circulating leucocytes especially NK cells. 
>Does anyone know the source of these cells? Is there a particular tissue 
>from which these cells come from?

Hmm... We definately have done this sort of thing to increase
leukocyte yields from blood, so I can tell you it does work. I don't
recall the increase in absolute number or increase in CD16/56 positive
(lymphoid scatter gate) cells, but it's there. You do definately get a
fairly large increase in granulocytes.

However consider this: these cells show a slight, but significant
lowering of response in standard functional assays. This is possibly
due to the fact that you've just sent adrenaline levels and other cool
mediators that elevate cAMP levels, sky high.  Result is inhibition of
and/or delayed responses.

It also possibly explains the reason for the leukocytosis: you've just
down regulated their adhesive abilities! These cells marginate in
highly micro-vascular sites like lung, bone marrow, lamina propria of
the gut, etc. Imagine the small ratio of large peripheral vessels
(specifically veins, I've never done arteriol sticks... Ow!) compared
to total microvasculature... Not hard to imagine a situation where you
release the leukocytes from transient (but importantly slow, constant,
and limiting) interaction, as well as constricting and redirecting
blood flow away from such sites! So now you've got released cells, and
they are shunted away from reinteracting in those same places,
resulting in increased PBL concentractions (the serum, and probably
redcells can still get in those other sites...).

For NKs, they are known to marginalize in lung, spleen, liver, bone
marrow, etc., and I'd propose similar exercise effects. I suspect
similar effects on their physiology, though I've never assayed
effector functions for NKs (eg target killing or cytokine produciton),
but as adhesive interactions are critical for NK activation (and
certainly recruitment), I wouldn't doubt it. I know nothing about
effects on NK activation signal transducion through CD16 or newly
identified NK receptors.

Sort of more than you probably wanted, but I doubt something simple
like a "bag-o-NKs" that just empties out when you run down stairs on
your way to the post-office before it closes.



(who's more interested in thinking about this stuff than actually
running up and down stairs to find out. You could take me kayaking or
skiing tho', and I'd be willing to donate the blood... Afterwards,
that is.)

"Nothing more is needed to destroy a man, than the conviction that his
life's work is useless."  -Antonin Artaud

erawtech at leland.stanford.edu (R. Aaron Warnock)

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