MB Research offers LLNA: BrdU ELISA protocol based on OECD Testing Guideline 442B, which was adopted as a standalone replacement for guinea pig sensitization testing in July 2010.
During the "induction phase" of sensitization, following exposure to a sensitizing test substance, lymphocyte proliferation occurs in the local lymph node. The LLNA measures increased proliferation of lymphocytes in the auricular lymph nodes (which drain the site of exposure; ears). Proliferation is assessed by determining the incorporation of the thymidine analog, bromodeoxyuridine (BrdU), into the DNA of lymph node cells using a special BrdU ELISA test kit.
The LLNA: BrdU ELISA Method is a non-radioactive variant of the Local Lymph Node Assay, which uses 5-bromo-2-deoxyuridine (BrdU) content, as an indicator of lymph node cell proliferation after exposure to potential dermal sensitizers.
Similar to the traditional LLNA, the LLNA: BrdU-ELISA is used to determine the induction phase of skin sensitization as well as provide quantitative data suitable for dose-response assessment.
Furthermore, an ability to detect skin sensitizers without the necessity for using dangerous radioactive isotopes for labeling of DNA eliminates potential issues of occupational exposure to radioactivity and hazardous waste disposal.