Assessment of contact sensitivity of four thiourea rubber accelerators: comparison of two mouse lymph node assays with the guinea pig maximization test.

Contact sensitivity of four thiourea rubber accelerators, diphenylthiourea (DPTU), dilaurylthiourea (DLTU), dibutylthiourea (DBTU) and diethylthiourea (DETU), was evaluated by a new sensitive mouse lymph node assay (SLNA) and the murine local lymph node assay (LLNA). The results of the SLNA and LLNA were compared with the data of the guinea pig maximization test (GPMT). In the LLNA and SLNA, the sensitizing activity was measured as a function of draining lymph node activation following application of the test chemicals. Of these four thioureas, three (DETU, DBTU and DPTU) were not classified as skin sensitizers in the LLNA. The SLNA successfully detected the sensitivity of all thioureas tested. This result indicated that the SLNA was, in these cases, more sensitive than the LLNA for identification of contact allergens. The order of sensitization potential observed from the SLNA was DPTU (greatest), DLTU, DBTU and then DETU (least). The predictions of sensitizing potential and the order of the sensitizing capacity of four thioureas by the SLNA and the GPMT are very similar.