Identification of metal allergens in the local lymph node assay

Background: The murine local lymph node assay (LLNA) has recently been endorsed as a validated alternative to guinea pig methods for the identification of skin sensitization hazard. Nevertheless, there has been some debate regarding the utility of this method for the detection of metal contact allergens. Objective: In these investigations, we have used the LLNA to determine the skin sensitization potential of 13 metal salts, 8 of which were considered to possess a significant ability to sensitize man, whereas the remaining 5 were judged to lack such potential. Results: The predictions from the LLNA were correct for 7 of the 8 (88%) sensitizing metals and for 4 of the 5 (80%) nonsensitizers when considered against the experience of these metals as human skin sensitizers. Thus, the overall predictive accuracy of the LLNA in relation to metals was 11/13 (85%), which is very similar to the accuracy of approximately 88% in relation to a much larger number of low- molecular-weight organic chemicals, as reported previously. Conclusion: These data provide support for the potential utility of the LLNA in hazard identification of metal contact allergens.