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 currentlyemployed to identify potential human contact allergens. At thistime, several companies are involved in both independent andjoint efforts to validate the MLLNA with their products. Thisreport describes the preliminary results of an Exxon-sponsoredresearch effort to validate the assay with selected materialsthat are representative of our company's diverse chemical andpetroleum product groups. Nine test materials were chosen forwhich there already existed guinea pig and/or human patch sensitizationdata. When the MLLNA results were compared to those data obtainedfrom currently used predictive tests (guinea pig, human patchtest), the MLLNA showed good agreement for moderate and strongsensitizers. However, the assay may be prone to the potentialconfounding effects of irritation (false positives), may beinsensitive to weak sensitizers, and may be influenced by vehicleselection.