National Toxicology Program

View document: Recommended Performance Standards: Murine Local Lymph Node Assay [PDF] View Table of Contents in webpage format Overview The LLNA was the first alternative test method evaluated and recommended by ICCVAM. Based on the recommendations of ICCVAM and an independent scientific review panel, the LLNA has been accepted by U.S. and international regulatory authorities as a stand-alone test method for assessing the potential of a substance to induce allergic contact dermatitis. ICCVAM currently routinely develops performance standards for test methods. Before a new test method is accepted for regulatory testing applications, validation studies are conducted to assess its reliability (i.e., the extent of intra- and inter-laboratory reproducibility), and its relevance (i.e., the ability of the test method to correctly predict or measure the biological effect of interest, which is partly dependent on the accuracy of the test method). Performance standards communicate the basis by which new proprietary (i.e., copyrighted, trademarked, registered) and nonproprietary test methods have been determined to have sufficient accuracy and reliability for a specific testing purpose. These performance standards can then be used to evaluate the accuracy and reliability of other proposed test methods that are considered functionally and mechanistically similar to the accepted test method.

When ICCVAM evaluated the LLNA in 1999, the concept of performance standards had not been developed. ICCVAM subsequently defined performance standards and described a process for their development (ICCVAM 2003). In 2007, the U.S. Consumer Product Safety Commission (CPSC) asked ICCVAM and NICEATM to evaluate the scientific validity of non-radioactive versions of the LLNA that could be used in place of the traditional LLNA, which measures the incorporation of radioactivity (3H-thymidine) in the draining auricular lymph nodes. ICCVAM decided at that time to develop performance standards that could be used to more rapidly and efficiently determine the validity of these and other modified versions of the LLNA.

The European Centre for the Validation of Alternative Methods (ECVAM) also independently drafted LLNA performance standards in 2007, and the Japanese Center for the Validation of Alternative Methods (JaCVAM) initiated two validation studies of modified LLNA test methods using a list of proposed reference substances to evaluate their validity. With an obvious international interest in developing LLNA performance standards, ICCVAM, JaCVAM, and ECVAM agreed to work together to develop internationally-harmonized LLNA performance standards.

ICCVAM has developed recommended performance standards for the LLNA and will publish them in 2009. These performance standards reflect extensive discussions that took place between ICCVAM, ECVAM, and JaCVAM during 2007 and 2008, and represent a set of internationally-harmonized standards for the conduct of the LLNA.