USE OF A SKIN-TEST ASSAY TO DETERMINE TUMOR-SPECIFIC CD8-CELL REACTIVITY( T)

We have observed delayed-type hypersensitivity (DTH) reactions in immu nized mice challenged subcutaneously with class I-binding peptides rel ated to rejection antigens recognized bq cytotoxic T lymphocytes on mu tagenized (tum(-)) variants of mastocytoma P815. As observed by skin t est in virally infected mice challenged with viral peptides, the intra footpad injection of tum(-) peptides resulted in a dose-dependent DTH that peaked at approximately 24 h. The response was mediated by CD8(+) cells and could be induced by previous vaccination of mice with live tumor cells, intrasplenic deposition of the eliciting peptide, or adop tive transfer with peptide-pulsed syngeneic dendritic cells. These sen sitization procedures resulted in an immunologically specific footpad reaction detectable for up to 2-6 months after priming. The evaluation by DTH in cancer patients of long-lived CD8(+) anti-tumor T cell resp onses following local challenge with tumor-specific peptides may be of great interest in human immunotherapy trials involving immunization a gainst identified tumor antigens.