A procedure for the development of allergic contact dermatitis in guinea pigs in which six potential allergens were used and a method for testing the effectiveness of barrier ointments, creams, and aerosols i n preventing contact dermatitis in sensitized guinea pigs (to oster oil) have been described.
HE CLINICAL testing and screening of protective T ointments, creams, and aerosols presents the obvious difficulty of finding a sufficient number of sensitized test subjects and also presents the danger of exposing a sensitized individual to allergen.
Eisen and his co-workers and a number of other investigators have described the production of allergic dermatitis in guinea pigs by the topical application of dinitrobenzene compounds (1-7), and Graul and Kalkoff (8) published a report of the sensitization of guinea pigs to topical application of inorganic salts. It was felt that a procedure involving application of test allergens to the ointment-protected skin of dermatologically sensitized guinea pigs might prove an effective method of evaluating protective ointments.
EXPERIMENTAL
Young female guinea pigs weighing about 350 Gm.
at the beginning of the study were used as the experimental animals. The hair of the dorsal skin was clipped with a Raycine electric clipper. Sensitization of Guinea Pigs.-Development of sensitization to the following potential allergens was attempted : dinitrofluorobenzene (0.01 M in alcoholpropylene glycol solution and in acetone-corn oil solution), ethyl aminobenzoate ( 5y0 in white petrolatum), sodium lauryl sulfate (5% aqueous solution), procaine hydrochloride (2% aqueous solution), chlorpromazine (2.5y0 aqueous solution), and oster oil (a cutting oil used by machinists).
Three procedures were studied for the sensitization of guinea pigs to dinitrofluorobenzene (DNFB). None of these methods employed the use of defatting solutions prior to the application of the potential allergen. In the first series, 0.07 ml. ( 3 drops) of 0.01 M l-fluoro-2,4-dinitrobenzene (Eastman) in absolute alcohol-propylene glycol, 1 : 1 solution, was applied to the anterior dorsal skin of each of ten guinea pigs of assorted skin colors. The solution was rubbed in, allowed to remain on the skin for 10 minutes, and was then removed with cleansing tissues. Application was repeated daily for a total of seven doses. The guinea pigs were allowed to rest 10 days and then an 0.045-ml. test dose was applied. The test dose showed low sensitization (see results) to DNFB in this vehicle and, therefore, as soon as the reactions cleared (2 days), these same guinea pigs were treated with 0.07 ml. of 0.01 M DNFB solution in acetone-corn oil 1 : 1. The solu-