Ability of delayed‐type hypersensitivity reactions to distinguish tumor‐associated antigens and histocompatibility antigens in soluble extracts from murine fibrosarcomas

The footpad swelling (FPS) test for delayed‐type hypersensitivity in the mouse was evaluated for its ability to measure both tumor‐associated antigens (TAA) and histocompatibility (H) antigens solubilized from methylcholanthrene (MCA) induced fibrosarcomas of C57Bl/6 (B6) mice. Tests for TAA were performed in mice immune to syngeneic tumors while H‐antigens were assayed in mice immunized with skin allografts. FPS was most intense in B6 mice challenged with TAA from the immunizing B6 tumor, but also occurred in response to cross‐reactive TAA solubilized from another B6 fibrosarcoma. Tests for tumor‐associated H‐antigens in allograft immune mice were strongly positive in response to donor/recipient H‐antigen differences and proved sensitive to shared third‐party H‐antigen differences. Comparison of soluble antigens from the same tumor maintained in vitro and in vivo revealed that, while both TAA and H‐antigens could be detected in preparations from the in vivo tumor line, only TAA and not H‐antigens could be detected by FPS in extracts prepared from the in vitro tumor line. These experiments have demonstrated that the mouse FPS test can distinguish both TAA and H‐antigen specificities present in the same complex mixture of tumor‐cell antigens.