Oral and epicutaneous desensitization in urushiol contact dermatitis in guinea pigs sensitized by 2 methods of different sensitizing potency

This investigation was conducted to study the relationship between the diff erent intensities of sensitization to urushiol induced by the maximization test method (MT) or by the ear-flank method (EF) in guinea pigs, and hypose nsitization induced by repeated oral and/or epicutaneous administration of the allergen, and to compare the immune tolerance achieved between these ro utes of dosing. During the observation period of 10 weeks, both oral and ep icutaneous administration produced hyposensitization to urushiol after weak sensitization by EF: however, only combined administrations via the oral a nd epicutaneous routes achieved hyposensitization after potent sensitizatio n, while inadequate tolerance was induced by oral dosing and none by epicut aneous dosing. Thus, it is indicated that difficulty in establishing immune tolerance may increase with increasing intensity of primary sensitization, and that hyposensitizing potency tends to increase in the order epicutaneo us, oral and combined (e.p. + p.o.) administrations of urushiol.