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After 48 hours of exposure to the test substance CD 86 expression was not induced in U937 cells at concentrations between 125 and 2000 µg/mL. From this it has to be concluded that test substance does not induce dendritic cell activation.

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The aim of this study was the predicition of skin sensitising potential using human pro-monocytic cell line U397 as a surrogate for dendritic cells. As readout, the change in the expression of the cell membrane marker CD86 measured by flow cytometry after 48 hours of the test exposure is determined. In this test system the test substance is predicted to activate dendritic cells when the CD86 cell surface expression exceeds a threshold of 1.2 in relation to vehicle treated cells in at least two independent experiments at any tested sufficiently non cytotoxic (cell viability ≥70 %) concentration. The test item was tested in five concentrations: 125, 250, 500, 1000, 2000 µg/mL. The strong sensitizer ethylene diamine (EDA, 70 µg/mL) was used as positive and lactic acid (LA, 200 µg/mL) as non-sensitizing negative control. The cytotoxicity of the test substance Cetiol Sensoft was evaluated by flow cytometry using propidium iodide staining after 48 hours exposure.

CD 86 expression was not induced after 48 hour treatment with lactic acid and was induced after 48 hours exposure to EDA. The level of expression was within the range of the historical negative and positive control data. No cytotoxicity was observed up to 2000 µg/mL of Cetiol Sensoft under the chosen exposure conditions on U937 cells. No decrease in cell viability below 70% was observed. In the first experiment a borderline induction of the expression of CD 86 was observed at a sufficiently non-cytotoxic (cell viability ~ 70%) concentration but could not be reproduced in the second and third experiment.

In summary, after 48 hours of exposure to the test substance CD 86 expression was not induced in U937 cells at concentrations between 125 and 2000 µg/mL. From this it has to be concluded that test substance does not induce dendritic cell activation. (BPCN, 2012)