Local lymph node assays.

The murine local lymph node assay (LLNA) allows identification of chemicals that have the potential to cause skin sensitization and allergic contact dermatitis. In this test, contact allergens are identified as a function of events occurring during the induction phase of skin sensitization; specifically, stimulation of proliferative responses in draining lymph nodes measured as a function of radiolabeled thymidine incorporation in situ. Two methods are presented. In one, lymph nodes are pooled on an experimental group basis, while in the other, lymph nodes of individual animal are pooled, which enables statistical analyses. These methods have been developed for contact sensitization hazard assessment and provide a robust and reliable method as an alternative to guinea pig tests which measure skin sensitizing potential as a function of challenge-induced skin reactions in previously sensitized animals. It is also possible to use LLNA data for measurement of relative potency in terms of risk assessment.