Following a 2008 evaluation, ICCVAM concluded that the reduced murine local lymph node assay (rLLNA) can be used to distinguish between skin sensitizers and nonsensitizers when conducted according to the ICCVAM-recommended murine local lymph node assay (LLNA) protocol. ICCVAM recommends that the rLLNA test method be used routinely before conducting the multidose LLNA in cases that do not require dose-response information or if the test substance is expected to have no allergic contact dermatitis hazard potential. Used appropriately, the rLLNA can reduce animal use by 40% for each test compared to the multidose LLNA.
The ICCVAM Test Method Evaluation Report: The Reduced Murine Local Lymph Node Assay: An Alternative Test Method Using Fewer Animals to Assess the Allergic Contact Dermatitis Potential of Chemicals and Products includes recommendations for rLLNA use, its limitations, standardized protocols, and future studies.
The LLNA is an alternative test method for assessing the allergic contact dermatitis potential of a substance in humans. The assay requires fewer animals and less time than traditional tests such as the guinea pig maximization test and the Buehler test. Compared to guinea pig tests, the LLNA also provides dose–response information and avoids animal pain and distress associated with a skin sensitization response.
The rLLNA, also referred to as the “cut-down” or “limit dose” LLNA, was one of several modified versions of the LLNA nominated by the U.S. Consumer Product Safety Commission in 2007 for evaluation by ICCVAM and NICEATM.
ICCVAM and NICEATM prepared a draft background review document and draft test method recommendations for use of the rLLNA. These documents were reviewed in a public meeting by an independent international scientific peer review panel. In finalizing their test method recommendations, ICCVAM considered the panel’s conclusions and recommendations, those of the Scientific Advisory Committee on Alternative Toxicological Methods, and comments from the public.
The U.S. Environmental Protection Agency adopted the rLLNA, noting in their announcement that the rLLNA allows for a 40% reduction in animal use compared to the multidose LLNA.
April 2011 EPA policy document
NICEATM and ICCVAM subsequently developed a revision to Test Guideline 429, the LLNA test guideline issued by the Organisation for Economic Co-operation and Development (OECD). The revised Test Guideline 429 incorporates the rLLNA procedure. It was adopted by the OECD in July 2010.
Revised OECD Test Guideline 429