The local lymph node assay (LLNA)

The murine local lymph node assay (LLNA) is awidely acceptedmethod for assessing the skin sensitization potential of chemicals. Compared with other in vivo methods in guinea pig, the LLNA offers important advantages with respect to animal welfare, including a requirement for reduced animal numbers as well as reduced pain and trauma. In addition to hazard identification, the LLNA is used for determining the relative skin sensitizing potency of contact allergens as a pivotal contribution to the risk assessment process. The LLNA is the only in vivo method that has been subjected to a formal validation process. The original LLNAprotocol is based onmeasurement of the proliferative activity of draining lymph node cells (LNC), as determined by incorporation of radiolabeled thymidine. Several variants to the originalLLNAhave been developed to eliminate the use of radioactivematerials. One such alternative is considered here: the LLNA:BrdU-ELISA method, which uses 5-bromo-2-deoxyuridine (BrdU) in place of radiolabeled thymidine to measure LNCproliferation in draining nodes. © 2012 by John Wiley & Sons, Inc.