Poison ivy doesn't bother me. When I was 6 years old, I was out in the woods with my buddy Michael. We found a big poison ivy vine, and I told Michael if he had the nerve to eat a big leaf, I would too. We both ate fresh green poison ivy leaves the size of my palm. Michael got covered with poison ivy, even on his eyelids, and had to go to the doctor. And our parents said, "Michael! Simon!! You ate what??" Our parents didn't know whether to whip our ass, or to send us to a psychiatrist. I didn't get sick. True story. I may have invented a vaccine against poison ivy.
I am still immune to poison ivy. Up here in the NC mountains we have enormous poison ivy vines, 3 inch diameter and running right to the top of 90 foot trees. I have cut big vines in two on 30 or 40 trees, just to kill the PI. I have wacked a dozen locust trees that were covered in PI vines, that's why I said that tree might be locust. As someone said, cutting poison ivy with a chain saw, you get sprayed with poison ivy juice. Doesn't bother me.
The only way poison ivy affects me is, if I have a fresh nick on my arm, a place where I got pricked by a thorn, and if I get poison ivy juice in that fresh nick, I will get a poison ivy infection about the size of a penny. I must say that is not pleasant. However the little poison ivy infection does not spread and it goes away in a few days.