ASSESSMENT OF THE SKIN SENSITISATION POTENTIAL IN THE MOUSE USING THE LOCAL LYMPH NODE ASSAY (LLNA) BrdU METHOD

OCDE 442B

The basic principle underlying the local lymph node assay (LLNA) is that sensitizers induce proliferation of lymphocytes in the lymph nodes draining the site of substance application.

Under appropriate test conditions, this proliferation is proportional to the dose applied, and provides a means of obtaining an objective, quantitative measurement of sensitization.

The test measures cell proliferation as a function of in vivo radioisotope ( 3 H-methyl thymidine) incorporation into the DNA of dividing lymphocytes, and assesses this proliferation in the draining lymph nodes proximal to the application site.
Due to the use of radioactivity, the LLNA has limited use in regions where the acquisition, use, or disposal of radioactivity is problematic.
The LLNA: BrdU-ELISA was therefore developed as a nonradioactive modification to the LLNA, which uses nonradiolabelled 5-bromo-2-deoxyuridine (BrdU) (Chemical Abstracts Service Registry Number [CASRN] 59-14-3) with detection by an enzymelinked immunosorbent assay (ELISA) to assess lymphocyte proliferation. The ability to detect skin sensitizers without the necessity of using a radioactive label for DNA eliminates the potential for occupational exposure to radioactivity and waste disposal issues.
Similar to the LLNA, the LLNA: BrdU-ELISA studies the induction phase of skin sensitization and provides quantitative data suitable for dose-response assessment. Lymphocyte proliferation in test groups is compared to that in the concurrent vehicle-treated control group. The proliferation is proportional to the dose and to the potency of the applied allergen and provides a simple means of obtaining a quantitative measurement of sensitization. The LLNA: BrdU-ELISA assesses this proliferation as the proliferation in test groups compared to that in vehicle treated controls.

 

 

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