National Toxicology Program

Overview

The murine local lymph node assay (LLNA) is a stand-alone test method for assessing the hazard potential of a test substance to induce allergic contact dermatitis in humans. After a recent evaluation of data in an expanded LLNA database, ICCVAM recommended that the LLNA may be used to test any chemical or product unless the chemical or product to be tested has properties that may interfere with the ability of the LLNA to detect sensitizing substances. The ICCVAM recommendations on the applicability domain of the LLNA have been transmitted to Federal agencies, which accepted or endorsed the ICCVAM recommendations.

View letters to Federal agencies communicating ICCVAM recommendations

Background

Following its original evaluation of the LLNA in 1999, ICCVAM recommended the LLNA as a valid alternative to traditionally accepted guinea pig test methods for assessing allergic contact dermatitis hazard potential for most testing situations. In January 2007, the U.S. Consumer Product Safety Commission (CSPC) requested that NICEATM and ICCVAM assess the validation status of new versions and applications of the LLNA, including use of the LLNA to evaluate a wider range of substances (broaden the applicability domain of the LLNA). Substances to be considered in this evaluation included pesticide formulations, metals, substances in aqueous solutions, and other products updated from the original ICCVAM recommendation on the LLNA.

The ICCVAM interagency Immunotoxicity Working Group (IWG), working with NICEATM, prepared a draft background review document (BRD) and draft recommendations for application of the LLNA for evaluating pesticide formulations, metals, substances in aqueous solutions, and other products. The draft BRD and draft ICCVAM recommendations were reviewed in a public meeting of an international independent scientific peer review panel (“Panel”) in March 2008. The Panel agreed with the ICCVAM assessment that more data were needed to evaluate these new applications of the LLNA. Additional data were submitted to NICEATM; NICEATM and the interagency IWG revised the BRD, and updated test method recommendations were developed by ICCVAM. A second Panel meeting to consider the revised documents was held in April 2009, and the Panel's report was made available in June 2009. ICCVAM considered the Panel’s report along with all public and SACATM comments received as they prepared final test method recommendations, which were forwarded to Federal agencies for their consideration in June 2010.

ICCVAM recommended that the LLNA may be used to test any chemical or product, including pesticide formulations, metals, substances in aqueous solutions, and other products such as natural complex substances and dyes unless the chemical or product to be tested has properties that may interfere with the ability of the LLNA to detect skin-sensitizing substances. The expanded applicability domain of the LLNA is expected to result in broader use of the LLNA, enabling reduction and refinement of animal use for identification of potential allergic contact dermatitis hazards.

National and International Acceptance of the Expanded Applicability Domain of the LLNA

View Federal Register notice announcing receipt of agency responses to recommendations (76 FR 2388, January 13, 2011) [PDF]

In April 2011, the U.S. Environmental Protection Agency announced that it was expanding the existing dermal sensitization guideline to include testing of end-use pesticide products using the LLNA. The EPA policy notes the animal welfare advantages of the LLNA as well as the ability of the LLNA to provide a more quantitative assessment of dermal sensitization than traditional guinea pig methods for assessing allergic contact dermatitis hazard potential.

View the April 2011 EPA policy document [PDF]

NICEATM and the IWG also developed a revision to the test guideline issued by the Organisation for Economic Co-operation and Development (OECD), OECD Test Guideline 429, that describes the conduct of the LLNA. The revised Test Guideline 429, which was adopted by OECD in July 2010, incorporates the updated applicability domain for the LLNA. It also includes the updated protocol for the LLNA and provides for the use of the reduced LLNA method when appropriate.

View the updated OECD Test Guideline 429 — Skin Sensitization: Murine Local Lymph Node Assay [PDF]

View publications and presentations on NICEATM-ICCVAM evaluations of the murine local lymph node assay for identification and classification of sensitizers

Federal Register Notices with Announcements Relevant to the ICCVAM Evaluation of the LLNA Applicability Domain

Independent Scientific Peer Review Panel Report: Updated Validation Status of New Versions and Applications of the Murine Local Lymph Node Assay: A Test Method for Assessing the Allergic Contact Dermatitis Potential of Chemicals and Products: Notice of Availability and Request for Public Comments

Announcement of a Second Meeting of the Independent Scientific Peer Review Panel on the Murine Local Lymph Node Assay; Availability of Draft Background Review Documents (BRD); Request for Comments

Peer Review Panel Report on the Validation Status of New Versions and Applications of the Murine Local Lymph Node Assay (LLNA): A Test Method for Assessing the Allergic Contact Dermatitis Potential of Chemicals and Products: Notice of Availability and Request for Public Comments

Announcement of an Independent Scientific Peer Review Panel Meeting on the Murine Local Lymph Node Assay; Availability of Draft Background Review Documents; Request for Comments

Murine Local Lymph Node Assay: Request for Comments, Nominations of Scientific Experts, and Submission of Data

View information about the 1998 LLNA Peer Panel meeting