Tumor-specific immunogenicity induced by chemical modification.

C57BL/6J spleen cells were immunized in vitro against cells from a syngeneic 3-methylcholanthrene-induced sarcoma, either modified with diazotized sulfanilic acid or left unmodified. The spleen cells were harvested after 5 days and run in a short-term 51Cr-release assay against unmodified tumor cells as targets. The spleen cells sensitized against the modified but not the unmodified tumor cells were cytotoxic for the unmodified tumor cell targets but not for two other syngeneic tumor cell lines or syngeneic spleen cells, thus indicating the production of tumor-specific cytotoxicity.