The murine local lymph node assay (LLNA) is an in vivo test for skin sensitisation.
The principle underlying the LLNA is that skin sensitizers induce growth of lymphocytes in the lymph nodes draining the site of application.
[2] The LLNA may not be appropriate for certain metallic compounds, surfactants, high-molecular-weight proteins, strong dermal irritants, and materials that do not sufficiently adhere to the ear for an acceptable period of time during treatment.
[3] The REACH Regulation, Annex VII, paragraph 8.3 states "The Murine Local Lymph Node Assay (LLNA) is the first-choice method for in vivo testing.
However, if a negative result is seen in the LLNA or MEST, a guinea pig test (preferably a GPMT or BT) must be conducted.