IDENTIFICATION OF CONTACT ALLERGENS BY HUMAN ASSAY .2. FACTORS INFLUENCING INDUCTION AND MEASUREMENT OF ALLERGIC CONTACT DERMATITIS

[摘要] Human volunteers were sensitized to a variety of contact allergens in order to identify the conditions which maximally promote the establishment of the allergic state. This information was required to design more effective methods for detecting contact allergens. While all inflammation-producing insults tend to be enhancing, chemical Irritation with sodium lauryl sulfate and dimethylsulfoxide were superior to physical traumata such as ultraviolet radiation and Scotch Tape stripping. The chemical irritant may be combined with the allergen or applied with equal effectiveness as a pre-treatment; the latter avoids chemical incompatibility. Above a certain minimum, sensitization for a fixed surface concentration is not dependent on the size of the area to which the allergen is applied. Sensitization, within limits, is proportional to the surface concentration of the allergen, and not on the total amount of allergen. High concentrations are required for weak allergens. Within limits, the sensitization rates are roughly proportional to the number of exposures, especially for weaker allergens. With agents not recognized as allergens, even 15 exaggerated exposures were incapable of inducing sensitization. For an equal number of identical exposures, higher rates result when each exposure is to the same extremity than when a different extremity is used for each application. Sensitization is more effective when each of a number of applications is confined to exactly the same inflamed skin site than when each application is to a fresh, nearby site. Higher sensitization rates are achieved by allowing rest periods between 24 hr. exposures. Forty-eight hr. exposures are superior to 24 hr. ones for weaker allergens. Three day exposures are not more effective than 2 day ones. The application of the allergen epicutaneously is far more sensitizing than the intradermal injection of the allergen. The optimal concentration for challenge patch testing is the highest non-irritating amount up to a maximum of 10%. The vehicle is an important factor in challenge patch testing. Petrolatum is the most generally useful and effective vehicle. The back is as sensitive as any other area practical for challenge patch testing.