RESUMEN
BACKGROUND: An extract of the tropical fern Polypodium leucotomos (PL) administered orally to mice inhibits ultraviolet B (UVB) radiation-induced skin cancer formation. UVB-induced murine skin cancers occur, in part, because of UVB-induced immunosuppression. Thus, we examined whether PL inhibits UVB-suppression of the induction of contact hypersensitivity (CHS) locally or systemically. METHODS: C57BL/6 mice received standard drinking water or water-containing PL. In the local model, mice were shaved on the dorsum and exposed to 3500 J/m(2) of UVB radiation daily for 4 days. Control mice were not irradiated. After the last irradiation they were sensitized to oxazolone topically at the irradiated site. To examine the ability of PL to inhibit systemic UVB-induced immunosuppression, mice were given 10,000 J/m(2) of UVB radiation once and immunized at a non-exposed site 3 days later. Six days after immunization (in both models), mice were challenged on the ears with oxazolone and 24/48 h ear swelling assessed. RESULTS: PL in drinking water significantly reduced the inhibition of CHS observed with exposure to UVB radiation in both the local and systemic models. CONCLUSIONS: The ability of PL to inhibit UVB radiation-induced immune suppression may explain, in part, its ability to inhibit UVR-induced skin cancer induction in mice.
Asunto(s)
Dermatitis Alérgica por Contacto/inmunología , Tolerancia Inmunológica/efectos de los fármacos , Extractos Vegetales/farmacología , Hojas de la Planta , Polypodium , Rayos Ultravioleta/efectos adversos , Animales , Dermatitis Alérgica por Contacto/etiología , Dermatitis Alérgica por Contacto/patología , Oído/patología , Tolerancia Inmunológica/efectos de la radiación , Ratones , Ratones Endogámicos C57BL , Oxazolona/administración & dosificación , Oxazolona/efectos adversos , Dosis de Radiación , Piel/inmunología , Piel/patologíaRESUMEN
Systemic exposure to allergens resulting in a cutaneous eruption is known as systemic contact dermatitis (SCD). Once sensitization occurs, varying exposures to antigens via multiple routes (including transepidermal routes, intravenous or intramuscular routes, inhalation, and ingestion) can result in systemic flare. This article highlights the different categories of common contactants, metals, medications, and plants, exposure to which leads to SCD. A comprehensive approach that takes into account all possible routes of exposure is essential in diagnosing SCD and in helping patients successfully avoid their allergens.