The use of ethanol:diethylphthalate as a vehicle for the local lymph node assay.

Abstract

The murine local lymph node assay (LLNA) is used for the prospective identification of contact allergens. This method is not only accepted as a stand-alone test for the identification of contact allergenic hazard but also used increasingly for the measurement of the relative potency of skin-sensitizing chemicals as an integral component of the risk assessment process. During the development and validation phases of the method, a list of standard vehicles for use in the LLNA was identified, among them being the vehicle most commonly used acetone/olive oil (4:1, AOO). We have now explored the performance in the LLNA of a non-standard vehicle, ethanol:diethyl phthalate (1:3, EtOH:DEP), that is used frequently to evaluate dermal effects of fragrance materials in both human and experimental studies. Current investigations have demonstrated that EtOH:DEP induces similar levels of background proliferative responses in lymph nodes comparable with the standard vehicle AOO. Moreover, expected levels of activity are observed when EtOH:DEP is used to deliver a known contact allergen in the LLNA. The conclusion drawn is that EtOH:DEP provides a suitable vehicle for use in the LLNA and that the approach described provides a basis for future evaluation of novel vehicles.