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Poison Ivy/Oak/Sumac
Published in Charles Theisler, Adjuvant Medical Care, 2023
Poison ivy, oak, and sumac are common poisonous plants on the North American continent. When these plants are touched, they deposit an oily sap called urushiol onto the skin. The sap is noted for its ability to create a localized type of allergic contact dermatitis with an uncomfortable, red, itchy, blistery rash. Poison ivy, oak, and sumac rashes are not contagious and cannot spread from one person to another even if there are open sores, because blister fluid does not contain urushiol. Only if another person touches the urushiol that is still on the affected person or his or her clothing can the rash be acquired.
Principles of Toxicology
Published in P. K. Gupta, Brainstorming Questions in Toxicology, 2020
Urushiol is the toxin found in poison ivy. It must first react and combine with proteins in the skin in order for the immune system to recognize and mount a response against it. Urushiol is an example of which of the following?
Antigens
Published in Constantin A. Bona, Francisco A. Bonilla, Textbook of Immunology, 2019
Constantin A. Bona, Francisco A. Bonilla
Haptens may complex with self proteins in vivo under certain circumstances, and generate new T cell epitopes. For example, non-immunogenic chemicals may react with components of skin, creating new immunogenic structures. A vigorous immune response to these new antigens results in a contact hypersensitivity reaction (see Chapter 6). An example of this is the catechol derivative urushiol found in certain plants of the genus Toxicodendron, more affectionately known as poison ivy.
Himalayan poisonous plants for traditional healings and protection from viral attack: a comprehensive review
Published in Toxin Reviews, 2022
Shriya Pathania, Diksha Pathania, Priyanka Chauhan, Mamta Sharma
Hay fever caused by pollen from ragweed, birch, hazel, timothy grass, and ryegrass is the common case of phytoallergy. Urticaria resulting from eating strawberries and allergy to peanuts are some other recognized allergy conditions due to phytoconstituents. Some phytoconstituents cause certain forms of extrinsic allergic alveolitis. Pyrethrum allergy is a known problem on the plantations of Chrysanthemum cineriaefolium in many countries. The Japanese cedar (Cryptomeria japonica) is a source of annual misery because of the massive amounts of highly allergenic pollen every spring (Wink and Van Wyk 2008). A Phytoallergic problem has increased greatly in recent decades. A different allergic mechanism occurs in regions with poison ivy (Rhus toxicodendron, T. rydbergii), poison oak (Rhus juglandifolia) and poison sumac (Rhus vernix). The active ingredient is urushiol. Its first exposer of sap to the skin has no noticeable clinical effect. Urushiol acts as a hapten, however. It binds to proteins in the skin, creating new epitopes. Upon subsequent contact pronounced pruritic dermatitis develops (Wink 2010).
Clinical and immunologic differences in cellulitis vs. pseudocellulitis
Published in Expert Review of Clinical Immunology, 2021
Michael Goldenberg, Henry Wang, Trent Walker, Benjamin H Kaffenberger
Allergic contact dermatitis (ACD) is a delayed type IV hypersensitivity reaction resulting from allergen-specific T cell activation [50]. When it is misdiagnosed as cellulitis, it is most often related to abrupt exuberant exposure such as plant dermatitis, ultraviolet light exposure, or paraphenylenediamine in hair dye. It is extremely unlikely for a rinse-off product like shampoo, detergents, or soaps to cause an abrupt reaction that could be confused with cellulitis. This condition typically starts with extensive itching, redness, microvesiculations in the skin, and develops into large bullae if severe. The presence of itch is often a distinguishing factor. In addition, linear streaks, scattered black dots (presence in urushiol-related dermatitis from poison ivy), and geometric patterns should help clinically differentiate patients.
Bioactivation of herbal constituents: mechanisms and toxicological relevance
Published in Drug Metabolism Reviews, 2019
Urushiol (Figure 11(h)), a pale-yellow oily mixture of catechols with an alkyl side chain, are the allergenic components of Toxicodendron radicans (poison ivy) and Toxicodendron diversilobum (poison oak). Brushing up against these plants results in allergic contact dermatitis, leading to an itchy rash. Oxidation of urushiols to ortho-quinones likely results in depletion of intracellular GSH and covalent modification of macromolecules leading to skin toxicity (Dunn et al. 1982). Urushiol-induced contact dermatitis is known to be mediated by T lymphocytes that recognize urushiol-bound proteins as an antigen (Dunn et al. 1982). Urushiol ortho-quinones and/or ROS production are likely also responsible for the DNA fragmentation observed in human cancer cells treated with urushiol leading to induction of apoptosis (Kim et al. 2013).