On Mon, 01 Jul 2013 07:47:19 -0400, Pat Kiewicz wrote:

As a kid, he spent much of one summer indoors due to an extreme reaction
(that required medical intervention and injections).

I think those who have had an extreme reaction have had a pretty good
dosage of the plant, since the oils do not migrate per se; the oils
are "spread" (just like any other oil) though, and, in fact, 1/4 of
an ounce of urushiol is said to be enough to infect all people on earth:
http://poisonivy.aesir.com/view/fastfacts.html

Given the amount on a pinhead can give 500 people the rash, it would
not take all that much to cover your body in the oil; hence the key
to preventing that extreme reaction is to avoid the urushiol in the
first place.

However, when you have to tunnel through 500 feet of the thick tangly
vines, there is no way to completely avoid exposure. All you can do
is ameliorate the damage by knowing thine enemy and knowing yourself
(which is what Sun Tzu taught us a few thousand years ago).

Given the minute amounts it takes to "infect", you can't avoid getting
the urushiol-laced sap on your skin; and, once on the skin (which is
inevitable when you're chain sawing the stuff for hours) it behooves
us to get it *off* the skin if we can. As soon as we can.

It turns out that it's not easy to *remove* urushiol from the skin
because the lipid easily diffuses past cell membranes deeper into
the layers of your skin within 15 minutes of exposure and then the
urushiol is oxidized into a quinone (i.e., an oxidized aromatic),
which binds to large skin proteins - which, I must emphasize,
are the real culprit in the type IV immune response.

Note: Type IV cell mediated immune responses have *nothing* to do
with humoral antibodies; so, the normal rules of immunity that most
people think of, as in vaccines, do not at all apply!

Since these now-modified proteins suddenly *appear* to be foreign to
our (randomly-sensitized) T lymphocytes, the T-cells elicit a vicious
but localized cytokine attack, which is sort of like throwing a purple
anti-personnel marker grenade into a foxhole. This cytokine grenade
basically marks all your cells in the localized vicinity of the
offending now-mutant protein for death. As soon as your circulating
white blood cells smell the cytokines, they turn into cannibalistic
zombies, who eat all the marked cells, thereby destroying not only
the mutant proteins - but also killing your uninfected cells, and,
in part, your nervous tissue, so, that's what's causing the classic
poison oak rash of redness (i.e., blood), blisters (i.e., lymph)
and itching (i.e., damaged nerves):
http://waynesword.palomar.edu/images2/urushiol1d.jpg

The trick in preventing or reducing the rash after the protein is
forced to the other side is to direct a probing attack at the
pentadecacatechol (aka hydroureshiol) quinone. You do this by
substituting a harmless decoy for the offending hapten before
the T-cells have had a chance to mark them with cytokines.

It turns out that spermicides, which are tiny surfactants, are just
the ticket for swapping themselves in place of the quinone on your
skin proteins. If you're late to the game, you need to scrape
the skin with something (anything) that will allow the surfactant
to reach the Langerhans cells. The Zanfel/Technu creams use little
balls of polyethylene; but I use baking soda or toothpaste (which
contains tiny grains of sand) to the same effect.

The magic of the expensive creams is that they scrub, oxidize,
wash away, and substitute themselves for the quinone. My poor-man's
Zanfel/Technu does the same thing (we hope) by scrubbing (baking
soda or toothpaste abrasive), oxidizing (dilute bleach or peroxide),
washing away (full-strength dawn dish detergent), and substituting
(industrial non-ionic cleaners such as nonyl phenyl ethoxylate).

http://www2.picturepush.com/photo/a/...g/11912430.jpg