Re: More on DU

[denison.8@osu.edu (Eric Denison)]

In reply to:

>> I do wonder how a DU particle
>> can lodge in a lymph node.

Aggie wrote:

>Recognized as foreign by macrophage, enGulfed [no pun intended] by
>macrophage, then macrophage travels to/stays in lymph node???

Unfortunately (or fortunately for our lymph nodes), there are several
things that would have to happen to our DU particle before the macrophage
gets to it.  (It's been a few years since we covered this in Biochem--if
I'm off base here, someone please let me know.  And let me know if there
are any reliable references discussing actual recovery of U or Pu from
lymph tissue).

First, it would have to travel one of three paths to a place where a
cellular response could be generated.  If inhaled, this means it has to be
small enough to pass through the natural filters of the victim's
respiratory system and somehow penetrate through the mucus and lodge in the
cell strata.  If it doesn't fully penetrate the mucus layer, it will be
cleared out of the lung and either coughed up or swallowed.  If ingested,
it would have to lodge in or be absorbed into the cellular lining of the GI
tract.  This is only really likely to happen if the substance is dissolved;
insoluble particulate matter should pass right on through (anyone know the
solubility of DU in concentrated HCl?).  The third path, of course, is
injection, which obviously puts the DU particle in direct contact with the
cells.

Regardless of which path it takes, our DU mote would have to be recognized
as foreign by immune cells (T-lymphocytes, I think), and get chemically
tagged for destruction.  Dissolved molecules from digested solids would be
far too small to evoke this response.  Primary responsibility for chemical
detox in this case would fall to the liver.  Any particles over a few
cell-diameters in size should be too large to provoke a macrophage
response.  Instead, the body would react to the tissue damage caused by the
foreign particle (or traumatic introduction thereof) just like it responds
to a splinter: send leukocytes to clean up the debris from the damaged
cells and any bacterial contamination, then encyst the invading
macroparticle and waste products as completely as possible.  The result is
generally a pustule of some sort.

All in all, I find it highly improbable that DU in the form(s) to which
Iraqi civilians (or even soldiers) would be exposed could lead to lymphatic
localization of detectable amounts of radioactive materials.  If someone
has reliable data to the contrary, let me know.  I'd be happy to admit my
error(s) and get (re) educated.


J. Eric Denison
Nuclear Engineering Program
The Ohio State University
2030 Robinson Laboratory
206 West 18th Avenue
Columbus OH 43210
(614) 292-3681 or -1074
denison.8@osu.edu


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