[pct-l] poison oak

[blisterfree at isp01.net (Brett)]

> 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