To: North American Fruit Explorers <nafex@lists.ibiblio.org>
Subject: [NAFEX] was nettles, now poison ivy & oral tolerance
Date: Fri, 27 Apr 2007 11:20:52 -0500
At 10:47 AM 4/27/2007, Doc L. wrote:
I have also heard that the Native Americans fed their children
poison ivy leaves to develop an immunity tolerance to it. (sic!)
It's true.
Now, whether or not they knowingly/intentionally did this or whether
it was just part of their culture, is another matter.
In the book, "It Will Live Forever", a tome on traditional Yosemite
acorn preparation, Julia Parker indicated that the Paiute/Yosemite
women often wrapped balls of acorn meal in poison ivy/oak
leaves. This would certainly have resulted in exposure to urushiol
via an oral route, which could - and probably did - provide them with
'oral tolerance' , an immunologic phenomenon in which if one is
exposed to a potential allergen via an oral route - at an early age -
one's immune system is less likely to respond adversely/excessively,
as may be the case when exposed via a transcutaneous route.
It's almost as if the oral exposure causes the immune system to look
at that allergen/antigen as 'normal', and possibly even as 'self'.