Assessment of the sensitizing potential of textile disperse dyes and some of their metabolites by the loose-fit coculture-based sensitization assay (LCSA).

Certain textile disperse dyes are known to cause allergic reactions of the human skin. Here, we examined 8 disperse dyes and 7 products of azo-cleavage of these dyes in an in vitro assay. We used the loose-fit coculture-based sensitization assay (LCSA) of primary human keratinocytes and of allogenic dendritic cell-related cells for combined testing of the sensitizing and irritative properties of these substances. The obtained data were compared to data generated in a modified version of the local lymph node assay by our working group. Disperse Blue 1 (DB1), p-nitroaniline (pNA) and p-aminoacetanilide (AAA) showed no sensitizing potential under our experimental conditions. Disperse Blue 124 (DB124), Disperse Yellow 3 (DY3), Disperse Orange 37/76 (DO37), Disperse Blue 106 (DB106), Disperse Red 1 (DR1), 2-amino-p-cresol (ApC), Disperse Orange 3 (DO3) and 2,6-dichloro-4-nitroaniline (DCh) were categorized as extreme sensitizers. Para-phenylenediamine (pPD) was categorized as strong sensitizer, and 2-amino-5-nitrothiazole (ANT) and 2-(N-ethylanilino)-ethanol (EAE) as weak sensitizers. All dyes, except for DB1, and ApC turned out to be strong irritants. DB1, ANT and DCh showed only weak irritative potential. PPD, pNA, EAE and AAA did not show any irritative effect at the concentration range tested. These results correlate with data derived from the modified version of LLNA and human data. Therefore, the LCSA represents a suitable test system to simultaneously analyse two crucial properties of substances relevant for allergy induction.