Interleukin 6 production in vitro: An alternative read-out for the local lymph node assay

The murine local lymph node assay has been developed as an alternative method for the identification of contact allergens. In contrast to guinea pig tests, which rely on visual assessment of challenge-induced dermal reactions, the local lymph node assay measures events occurring during the induction of skin sensitization. Contact allergic potential is measured as a function of hyperplastic responses in draining lymph nodes following systemic administration of [(3)H]thymidine. We have now examined whether the production in vitro of interleukin 6 (IL-6) by draining lymph node cells isolated from sensitized mice provides an alternative endpoint for the local lymph node assay. In comparative experiments, the production of IL-6 by lymph node cells in culture correlated closely with proliferative responses in vitro. Only chemicals known to cause contact sensitization elicited measurable (> 150 pg/ml) IL-6 production; non-sensitizing chemicals, including skin irritants, did not. Experience to date suggests that IL-6 production may provide a useful alternative read-out for the identification of chemicals which have a significant skin-sensitizing potential.