Local Lymph Node Assay (BrdU-ELISA)

Dermal Sensitization Testing

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The purpose of this study is to determine the sensitizing potential of topically applied test articles. This LLNA protocol, utilizing the BrdU ELISA method, is designed to be a stand-alone assay for dermal sensitization as described in the NIH report "The Murine Local Lymph Node Assay: A Test Method for Assessing the Allergic Contact Dermatitis Potential of Chemicals/Compounds," NIH No. 99-4494, and the LLNA test guidelines as defined in EPA OCSPP 870.2600 and OECD Guideline for the Testing of Chemicals No. 442B.

Skin Sensitization Testing

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 assay, 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.

The LLNA-BrdU assay allows for the detection of skin sensitization without the necessity for using dangerous radioactive isotopes for labeling of DNA eliminates potential issues of occupational exposure to radioactivity and hazardous waste disposal.

What are In Vivo Sensitization Tests?

Test methods designed to identify substances with skin sensitization potential or cause allergic contact dermatitis, which is an important element in evaluating toxicity. Below are the available in vivo tests for dermal sensitization available:

In Vivo Sensitization Testing Assays