RE: More on DU

["Jeri L. Anderson" <janderson@mjwcorp.com>]

Actually, one of the clearance pathways of particles from alveolar region of
the lung is the translocation of particles to the tracheobronchial lymph
nodes.  I have several references on the subject and I would be happy to
share them with you.  One reference suggests that the particulate burdens in
the nodes can be as high as 10% of the initial alveolar burden.  The exact
mechanism of the clearance pathway is unknown.  It has been proposed that
the particles are transported across the alveolar epithelial barrier by Type
I cells.  Once in the free space, the particles are then phagocytized by
interstitial macrophages which then enter the lymphatic vessels.  It has
also been theorized that the alveolar macrophages may actually carry the
particles through the epithelium and interstitium then into the lymph nodes
themselves.



> -----Original Message-----
> From: radsafe@romulus.ehs.uiuc.edu
> [mailto:radsafe@romulus.ehs.uiuc.edu]On Behalf Of Eric Denison
> Sent: Sunday, August 01, 1999 12:17 AM
> To: Multiple recipients of list
> Subject: Re: More on DU
>
>
> 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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