- Name & Description:
-
Classical Local Lymph Node Assay (LLNA)
Skin sensitization is an immunologically-mediated cutaneous reaction to a substance. The principle behind this test is that sensitizers induce a proliferation of lymphocytes in the lymph node draining the site of chemical application. Mice are exposed topically to the test substance on the dorsum of both ears and then after a few days, radiolabeled thymidine or deoxyuridine is injected through the tail vein. After the draining auricular lymph nodes are excised, lymphocyte proliferation is described as a function of in vivo incorporation of radiolabeled thymidine, measured by β-scintillation counting as disintegrations per minute (DPM). Proliferation is proportional to dose and potency of substance application. Classification of a chemical as a sensitizer is calculated using the Stimulation Index (SI): where DPM for each treatment group is divided by DPM of the vehicle control group. SI≥3 indicates a positive response.
- Validation Status:
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EU: Endorsed as valid by ECVAM (2000)
US: Endorsed as valid by ICCVAM and recommended for use as a stand-alone substitute for the guinea pig sensitization test (1999)
- Regulatory Status:
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OECD: TG 429 (2010)
International Standards Organization [ISO] 10993-10: Tests for Irritation and Sensitization (2002)
EU: Method B.42 in Annex to 440/2008/EC (2004, 2008)
US: EPA Health Effect Testing Guidelines on Skin Sensitization (2003)
- Effect or Potential Effect on Animal Use:
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Reduction
Refinement
(Does not require dermal hypersensitivity reactions be elicited in the animals; does not require administration of an adjuvant which causes pain and distress)
