6. OECD Test No. 442B: Skin sensitization. Local lymph node stimulation test (BrdU-ELISA)

The BrdU-ELISA local lymph node stimulation assay (ELGL: BrdU-ELISA) is a non-radioactive variant of the ELGL method that aims to identify sensitizing chemicals and measure the lymphocyte proliferation they induce in the auricular lymph nodes. This method, described in mice (CBA/JN strain), is based on the quantification of 5-bromo-2–deoxyuridine (BrdU), a thymidine analog, in lymphocyte DNA as an indicator of this proliferation. A minimum of four animals are used per dose group, with a minimum of three concentrations of the test substance, plus a negative control group treated with the vehicle alone, and a positive control, if necessary. The experimental protocol lasts six days.

The animals are then euthanized and a single-cell suspension of lymph node cells (LNC) is prepared. The LNC dispersion procedure is a crucial step, particularly for the very small lymph...