Streptozotocin: inherent but not expressed skin sensitizing activity.

We have shown previously that the alkylating agent streptozotocin (STZ) fails to induce responses in the murine local lymph node assay, a predictive test for contact sensitizing potential. In the present study, we demonstrate that this same compound when injected intradermally into the ears of mice provokes a dose-dependent induction of draining lymph node cell proliferation. These data indicate that the intrinsic immunogenicity of STZ is not displayed in the local lymph node assay under conditions of conventional topical exposure, secondary to a failure to cross the lipophilic stratum corneum in sufficient quantities. This finding has implications for the discernment of structure-activity relationships in contact sensitization.