EFFECT OF LOCAL ALLERGEN PRIMING ON EARLY, LATE, DELAYED-PHASE, AND EPICUTANEOUS SKIN REACTIONS

Allergic disease is renected in a chronic inflammatory response to an allergen. It is thought that local allergen priming underlies this chr onicity. To assess the effect of allergen priming on the amplitude and histologic effect of the allergic reaction, four sequential, intracut aneous skin tests were done with 48-h intervals in 13 patients allergi c to the house-dust mite Dermatophagoides pteronyssinus (Dpt). Reactio ns were measured at 15 min, and at 6, 24, and 48 h. Subsequently, epic utaneous tests were done on Dpt-primed spots (n=5). At 6, 24, and 48 h , reactions increased after priming (P <0.006), with unaltered early r eactions, Epicutaneous reactions to Dpt on primed spots were larger th an in epicutaneous controls on similarly primed skin. Local intraderma l priming results in greater inflammatory responses at both intra- and epicutaneous challenge. This mechanism may explain the chronicity of allergic reactions at epithelial surfaces.