Evaluation und Standardisierung von Hauttestungen zur Diagnostik der irritativen Kontaktdermatitis

Irritant patch testing is often performed as a 24 or 48 hour (h) occlusive patch test with low concentrations of sodium lauryl sulfate (SLS). The aim of this study was to investigate potential ways to shorten this test procedure and precise test results. 36 healthy volunteers underwent irritant patch testing with different pretreatments (PT) of the test fields. Occlusive test chambers were applied on the upper back with SLS 0.5%, 1%, 2% and 5% in large Finn Chambers. The patches were removed after 4 and 24 h, respectively, depending on the used concentration. Test fields were pretreated as follows: PT 1. field without any PT (control), PT 2. prick with lancet, PT 3. prick with test stamp, PT 4. scratch with lancet, PT 5. incision with standardized incision instrument (0.1-0.2 mm depth). Skin reactions were evaluated by transepidermal water loss (TEWL), skin erythema (EI) and skin hydration (HY) and as well by a visual score (VS) at 4, 24 and 72 h. Data show an obvious distinction between PT 1 - 3 and PT 4 - 5 at all measurement methods. The average TEWL values with PT 4 - 5 were higher than these with PT 1 - 3, especially on the 4 h-course. This distinction may derive from shape and size of the skin impairment achieved by PT 4 - 5, leading to a mechanical barrier disruption. However, SLS may infiltrate directly into deeper skin layers supported by capillarity. Consequently, no or little penetration through the epidermis and interaction with its structures occurs, which is responsible for irritant skin reactions. The SLS dose in the upper skin layers is therefore lower at these PT. The less remaining dose of SLS also explains this distinction, especially for the VS. Additionally, there are presumed reactions in deeper layers of the epidermis and dermis at PT 4 - 5. All these data suggest a different reaction pattern from the classical irritant response. Therefore, application without any PT seems to be best suited for irritancy skin testing, especially for visual assessment. PT prior to irritant patch testing have shown to be unjustifiable. In the current study crescendo reactions were seen at visual scoring and the skin erythema. For the TEWL no delayed reactions have been discovered. Repeated measurements therefore are only useful for VS, skin erythema and skin hydration. A 4-hour test procedure for the SLS-skin irritation test can be recommended to make the test more practicable for the patient and the clinic. The following test procedure seems to be appropriate: Application of a 4-hour epicutaneous irritancy test with concentrations of SLS between 2 and 5 % without any pretreatment of the test fields. An appropriate clinical scoring consisting of TEWL and VS can be recommended.