Assessment of the ear swelling test and the local lymph node assay in hamsters

In a hamster model, we compared contact sensitivity to the metal salt, potassium dichromate, to that of oxazolone, a well-known strong sensitizing agent. Using the ear swelling test, originally developed in mice, no significant differences could be observed between animals treated with potassium dichromate and controls, although oxazolone-treated animals showed a significant increase in ear thickness compared to controls. These observations were confirmed using the local lymph node assay (LLNA) where oxazolone proved to be a strong sensitizing agent, and potassium dichromate only resulted in a weak response. When the draining auricular lymph nodes were compared with the inguinal lymph nodes in the LLNA, more pronounced effects were obtained with the auricular lymph nodes. This study indicates that, also in hamsters, the LLNA is a feasible sensitization test system.