Editing Allergy (section)

===Toxins interacting with proteins===
Another non-food protein reaction, [[urushiol-induced contact dermatitis]], originates after contact with [[poison ivy]], [[Toxicodendron pubescens|eastern poison oak]], [[Toxicodendron diversilobum|western poison oak]], or [[poison sumac]]. [[Urushiol]], which is not itself a protein, acts as a [[hapten]] and chemically reacts with, binds to, and changes the shape of [[integral membrane protein]]s on exposed skin cells. The immune system does not recognize the affected cells as normal parts of the body, causing a [[T-cell]]<nowiki>-</nowiki>mediated [[immune response]].<ref>{{cite web | vauthors = Hogan CM | url = http://globaltwitcher.auderis.se/artspec_information.asp?thingid=82914 | title = Western poison-oak: Toxicodendron diversilobum | archive-url = https://web.archive.org/web/20090721044257/http://globaltwitcher.auderis.se/artspec_information.asp?thingid=82914 | archive-date = 21 July 2009 | work = GlobalTwitcher | veditors = Stromberg N | date = 2008 | access-date = 30 April 2010 }}</ref>

Of these poisonous plants, sumac is the most virulent.<ref>{{cite book | vauthors = Keeler HL | date = 1900 | title = Our Native Trees and How to Identify Them | location = New York | publisher = Charles Scribner's Sons | pages = 94–96 }}</ref><ref>{{cite book | vauthors = Frankel E | title = Poison Ivy, Poison Oak, Poison Sumac and Their Relatives; Pistachios, Mangoes and Cashews | publisher = The Boxwood Press | location = Pacific Grove, CA | date = 1991 | isbn = 978-0-940168-18-3}}</ref> The resulting dermatological response to the reaction between urushiol and membrane proteins includes redness, swelling, [[papule]]s, [[Vesicle (dermatology)|vesicles]], [[blister]]s, and streaking.<ref name="Dermatlas">{{DermAtlas|-1892628434}}</ref>

Estimates vary on the population fraction that will have an immune system response. Approximately 25% of the population will have a strong allergic response to urushiol. In general, approximately 80–90% of adults will develop a rash if they are exposed to {{cvt|0.0050|mg}} of purified urushiol, but some people are so sensitive that it takes only a molecular trace on the skin to initiate an allergic reaction.<ref>{{cite journal |author1=Armstrong W.P. |author2=Epstein W.L. |title=Poison oak: more than just scratching the surface |journal=Herbalgram |volume=34 |pages=36–42 |year=1995 }} cited in {{cite web |url=http://waynesword.palomar.edu/ww0802.htm |title=Poison Oak |access-date=6 October 2015 |url-status=live |archive-url=https://web.archive.org/web/20151006212234/http://waynesword.palomar.edu/ww0802.htm |archive-date=6 October 2015 }}</ref>