Skin irritation, false positives and the local lymph node assay: A guideline issue?

David A. Basketter, Ian Kimber

    Research output: Contribution to journalArticlepeer-review


    Since the formal validation and regulatory acceptance of the local lymph node assay (LLNA) there have been commentaries suggesting that the irritant properties of substances can give rise to false positives. As toxicology aspires to progress rapidly towards the age of in vitro alternatives, it is of increasing importance that issues relating to assay selectivity and performance are understood fully, and that true false positive responses are distinguished clearly from those that are simply unpalatable. In the present review, we have focused on whether skin irritation per se is actually a direct cause of true false positive results in the LLNA. The body of published work has been examined critically and considered in relation to our current understanding of the mechanisms of skin irritation and skin sensitisation. From these analyses it is very clear that, of itself, skin irritation is not a cause of false positive results. The corollary is, therefore, that limiting test concentrations in the LLNA for the purpose of avoiding skin irritation may lead, unintentionally, to false negatives. Where a substance is a true false positive in the LLNA, the classic example being sodium lauryl sulphate, explanations for that positivity will have to reach beyond the seductive, but incorrect, recourse to its skin irritation potential. © 2011 Elsevier Inc.
    Original languageEnglish
    Pages (from-to)137-140
    Number of pages3
    JournalRegulatory Toxicology and Pharmacology
    Issue number1
    Publication statusPublished - Oct 2011


    • False positives
    • Local lymph node assay
    • Skin irritation
    • Skin sensitization


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