Poison Ivy and the Immune Response
A few weeks ago I felt incredibly lucky to be doing yard work. I usually leave outdoor chores to my husband, as I have rheumatoid arthritis. This means there are days when a sink full of dishes or a basket full of laundry is daunting enough, so maneuvering a lawn mower, leaf blower, or weed whacker seems impossible. However, I was having a “good day,” when the pain in my joints was minimal and a morning of pulling weeds felt manageable. I had a rough winter and spring, filled with infections and flares, that necessitated my husband and I operate in “survival mode.” We took care of our children, our jobs, and critical chores, but things like weeding our backyard were put on the backburner while I focused my energy on recovery.
Therefore, it was all the more satisfying to rip out the weeds that had taken advantage of my months of poor health. As I crouched among the plants, freeing them from vines and weeds, I was filled with the gratitude I always feel when my body allows me to use it fully. I felt strength and vitality flowing through me, and I was thankful for that feeling, as it isn’t possible to experience it every day.
Even better, I didn’t flare later in the day, as often happens after strenuous activity. I took a muscle relaxer at bedtime just in case, as muscle stiffness can exacerbate joint pain and I wanted to ward off potential morning agony. The next day I was not only spared a flare, but I didn’t even have the “activity hangover” of fatigue and mild swelling and pain that almost always occurs after I’m physically active. I was thrilled. However, it turned out I was not yet out of the woods in terms of paying for my day outdoors.
An exposure to poison ivy
Thirty-six hours after my morning of weeding I woke up in the middle of the night scratching all over. As the itchiness pulled me from semi-consciousness to full wakefulness, my fingertips felt bumps all over my body, and I wondered how I’d been so eaten by mosquitos without realizing it. I went to the medicine cabinet in search of anti-itch cream and saw that my legs, arms, and even parts of my neck and face were covered in an angry rash. For the first time in my life, I was having a nasty reaction to poison ivy.
How our immune system reacts to poison ivy
Poison ivy produces an oil called urushiol, which can cause an itchy and even painful rash. Interestingly, urushiol would actually be harmless if the immune system did not perceive it as a threat.1 While some substances cause immediate irritation when in contact with human skin, poison ivy symptoms do not appear for 12-72 hours after contact, when the immune system has detected the substance and, in the cases of those who are allergic to poison ivy, determines that the urushiol is a foreign invader. This leads the immune system to attack its own skin cells.
Does this sound familiar? Those of us with rheumatoid arthritis know that our immune systems have become confused and go after our joints, tissues, and organs rather than fighting germs. While researchers don’t fully understand why some people’s immune systems go rouge and fight our own bodies instead of focusing solely on viruses and bacteria, this process of “friendly fire” from our immune systems can cause a wide variety of autoimmune conditions.
However, whereas the majority of people do not suffer from this group of diseases, most individuals are prone to an immune system response to poison ivy, leading to the highly unpleasant rash. Yet, approximately 10-15 percent of the population does not develop a response to contact with urushiol, as their bodies do not interpret it as a threat that needs to be attacked.2
For 38 years I was one of those fortunate people who never had an unpleasant experience with poison ivy. Throughout my childhood and adulthood, there have been numerous occasions when my hiking or yard work companions would develop poison ivy rashes, yet I was always unscathed. Therefore, I didn’t give the plant much thought . . . until this summer.
My first poison ivy rash
My first poison ivy rash was severe. Luckily, I happened to have an infusion appointment a couple of days after it developed. By that point, I was sleep deprived from restless, itchy nights, and I had tried multiple over the counter products to no avail. I was desperate for some help. My rheumatologist added a corticosteroid to my infusion and prescribed oral prednisone as well. Having taken countless rounds of corticosteroids over the 20 years I’ve been battling RA symptoms, I took note that the same drug is used for poison ivy reactions.
I mentioned that I had previously been immune to poison ivy, and my doctor said that as my rheumatoid arthritis has been more active in recent months it’s possible my immune system has become more hypersensitive and now reacts to the plant oil.
No life-long immunity to poison ivy
The immune system is certainly mysterious, and the misdirection of my confused immune system already causes my rheumatoid arthritis symptoms in addition to making me more susceptible to infection. Finding out that it also makes me react to urushiol was a very unpleasant surprise, as for the next two weeks the painful itching in my blistered, breaking skin surpassed the discomfort in my joints.
Now that I’m aware that my immunity to poison ivy was not life-long, I will be taking far more precautions when performing any future yard work. For any readers who may likewise have been granted a respite from poison ivy response, you may want to consider taking these precautions before you ever develop a rash. Had I understood that poison ivy rash was actually caused by a confused immune system, I wouldn’t have assumed that I would always be immune to poison ivy, considering how perpetually confused my immune system is.
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- Poison Ivy: an Exaggerated Immune Response to Nothing Much. Poison Ivy Immunology. http://www.bio.umass.edu/micro/immunology/poisoniv.htm. Accessed July 29, 2016.
- A poison ivy primer. Smithsonian Insider. http://insider.si.edu/2014/08/poison-ivy/. Published December 2014. Accessed July 29, 2016.