Intra- and inter-laboratory reproducibility and predictivity of the HaCaSens assay: A skin sensitization test using human keratinocytes, HaCaT.

Due to considerable constraints in using animals for risk assessment, much effort has been directed at developing non-animal test methods. Developing assays for skin sensitization, the leading cause of contact dermatitis, is particularly important, but there are currently no in vitro skin sensitization tests that completely replace animal tests. HaCaSens, a simple skin sensitization test using non-transformed HaCaT cells, predicts keratinocyte activation by skin sensitizers with 75% sensitivity, 83% specificity and 77% accuracy in a previous study using 22 coded substances. Although the data show promising results, the number of tested substances is insufficient to prove predictive capacity. Moreover, reproducibility among different laboratories has not been studied. Here, three laboratories participated in a validation in order to assess HaCaSens feasibility for official validation. To examine transferability, intra- and inter-lab reproducibility and predictive capacity, HaCaSens was assessed on a set of 30 test substances coordinated by the Validation Management Team (VMT). The results showed satisfactory transferability as well as intra- and inter-laboratory reproducibility. Further assessment of its predictive capacity on 20 test substances demonstrated a sensitivity of 81.8% (18/22), specificity of 87.5% (7/8), and accuracy of 83.3% (25/30) in identifying skin sensitizers, which is comparable with presently validated assays, KeratinoSens™ and LuSens. This validation study shows that the HaCaSens assay is easily transferable, reproducible and highly predictable for identifying skin sensitizers.