The T.R.U.E. Test® Methodology

Conventional patch testing technology has been fully described in Chap. 3. The method is extensively used by the dermatological community throughout the world. A potential drawback is that allergens are not always evenly dispersed in petrolatum. This is illustrated by histological examination of different samples; indeed, allergen crystals of different size can be visualized. Nevertheless, the situation has improved considerably, in relation with the use of more performant machinery in the manufacture of allergens. On the other hand, the dosage of allergens may vary in different areas, as the allergens are manually dispensed. The T.R.U.E. Test® represents an alternative way of patch testing, which intends to avoid variations of the allergens applied on the skin. The methodology was initiated by Fischer and Maibach, at first, in San Francisco and, later on, in cooperation with the Pharmacia company (Uppsala, Sweden).