Screening petrochemicals for contact hypersensitivity potential: a comparison of the murine local lymph node assay with guinea pig and human test data.

Over the last few years, the Murine Local Lymph Node Assay (MLLNA) has received considerable attention as a more quantitative, less expensive alternative to the guinea pig assays currently employed to identify potential human contact allergens. At this time, several companies are involved in both independent and joint efforts to validate the MLLNA with their products. This report describes the preliminary results of an Exxon-sponsored research effort to validate the assay with selected materials that are representative of our company's diverse chemical and petroleum product groups. Nine test materials were chosen for which there already existed guinea pig and/or human patch sensitization data. When the MLLNA results were compared to those data obtained from currently used predictive tests (guinea pig, human patch test), the MLLNA showed good agreement for moderate and strong sensitizers. However, the assay may be prone to the potential confounding effects of irritation (false positives), may be insensitive to weak sensitizers, and may be influenced by vehicle selection.