Delayed Hypersensitivity Reaction to Poison Ivy

When a person comes into contact with poison ivy, they are almost guaranteed to break out into an itchy and annoying rash. This rash is a product of the body’s response from the reaction of the immune system called a delayed hypersensitivity reaction. This type of reaction generally takes between several to seventy-two hours to show symptoms. Symptoms of a hypersensitivity reaction include rash, pus around the rash, and fever. More severe symptoms include swelling of the lips, tongue and throat, difficulty breathing or swallowing, dizziness, weakness, and bluish lips. Any person showing signs of the severe symptoms should seek medical attention immediately (Wilson, n.d.). The other less severe symptoms can generally be treated with over the counter medicines.

Causes of the delayed hypersensitivity reactions are anything that changes the body’s normal function. When skin comes in contact with poison ivy, a chemical known as Urushiol is left on the skin. Once absorbed into the blood stream by the skin, antigen-presenting cells, called Langerhans cells in the skin, or macrophages present the antigen to the immune system. From there the T cells recognize the antigen as a foreign body. In response, the T cells send out inflammatory signal cells called cytokines. At that point the cytokines trigger the monocytes which then become macrophages. The macrophages become activated by the cytokine and begin to attack any tissue in its general vicinity. This could lead to severe tissue damage. (Martz, n.d.)

Urushiol is made up of a mixture of catechol derivatives, the most common found on poison ivy being pentadecylcatechol. Although many people believe that poison ivy is harmless after the plant has died, that isn’t the case. Urushiol has been found to stay on a surface for several years. The best way to attempt to prevent a delayed hypersensitivity reaction to poison ivy, once contact has been made is to wash the surface of the skin immediately, dry, and pat with a cotton ball soaked in rubbing alcohol. Immediately remove and wash clothing that may have also come into contact with the plant. (Wilson, n.d.). Generally a person’s first initial contact with poison ivy they won’t have a reaction, but once the antigen has been introduced into the body, you’re almost guaranteed too after that. On the bright side, it’s believe that with age and repeat exposure a person becomes less sensitive to poison ivy.

References

Martz, E. (n.d.). Poison Ivy: an Exaggerated Immune Response to Nothing Much. Retrieved from http://www.bio.umass.edu/micro/immunology/poisoniv.htm#pi-dh PhD, S. A. (n.d.). Delayed Hypersensitivity Reactions. Retrieved from http://emedicine.medscape.com/article/136118-overview#a0199 Wilson, S. (n.d.). How Poison Ivy Works. Retrieved from http://science.howstuffworks.com/life/botany/poison-ivy2.htm