[pct-l] poison oak

[jeffmoorehead1 at cox.net (Jeff Moorehead)]

I always understood the rash to be the result of an overreactive immune 
response (hyperimmunity)-- meaning it is overkill by the immune system. The 
variation in reactivity is a result of variation in the degree of response 
of the immune system. For example, with some types of pollen, some people 
will simply sneeze while others will develop a serious hay fever. And it 
should, in theory, become worse with repeated exposure for reasons stated 
earlier. Sometimes immune systems go completely haywire against pathogens--  
especially novel ones. Some of the hemmoragic viruses, like hantavirus and 
ebola represent the most severe form of hyperimmune response. People 
actually drown in the fluid secreted by lung cells as part of the immune 
response.

Oils like urushiol and many other secondary compounds in plants are thought 
to function primarily as defensive insecticides or insect repellents. 
Insects are the main enemies of plants-- a long-standing rivalry which has 
driven forward the evolution of many unique secondary plant substances. The 
effect on us humans is purely incidental and can be unfortunate (like poison 
oak). Yet in some clear cut cases, it s most fortuitous: caffeine, cocaine, 
and THC. So there...drive on!

----- Original Message ----- 
From: "Brett" <blisterfree@isp01.net>
To: "Matt Bradley" <bodhisattvavow@hotmail.com>; "PCT-L" 
<pct-l@mailman.backcountry.net>
Sent: Wednesday, March 02, 2005 11:06 PM
Subject: Re: [pct-l] poison oak


>> blisterfree wrote: "Are those of us who are most likely to have run-ins 
>> with
>> poison oak in fact the least likely be adversely affected by
>> it? Anyone care to scratch this philosophical itch?"
>>
>> Interestingly, urushiol reactivity is highly variable. Even though we 
>> often
>> speak of a person being "immune" to it the reaction actually has nothing 
>> to
>> do with the immune system.  In fact it is an allergic reaction.
>
> Definition of allergy, per casual web search:
>
> "Allergy refers to the immune system's hypersensitivity to an offending 
> substance involving elevation of specific antibodies due to antigen 
> stimulus. It is an immune system reaction to a substance that other people 
> find harmless. Allergic reactions are classified into two categories, 
> immediate and delayed, up to 72 hours. They can range from mild to severe 
> which can cause anaphylactic shock."
>
> I would just add that the immune system's job is to defend the organism 
> from attack by foreign bodies. Sometimes it does the right thing, 
> sometimes it doesn't. Pollen is generally harmless, in any of itself, but 
> the immune system often decides to try fighting it off, thus we develop 
> season allergies. Urushiol, in and of itself, is likewise harmless. It is 
> not battery acid, for instance. But the plants containing urushiol have, 
> in effect, adapted to benefit from the fact that some organisms do develop 
> an immune response, aka allergic reaction, to the stuff. It's an 
> evolutionary game of charades, like the gopher snake "rattling" as if he 
> has the venom of a diamondback.
>
> - bf
>
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