In vitro induction of tumour-specific immunity V. Detection of common antigenic determinatnts of murine fibrosarcomas.

Two 3-methylcholanthrene and a spontaneous BALB/c fibrosarcoma were examined for tumour-associated antigens (TAA) by in vivo and in vitro induction of tumour-immune responses. When BALB/c mice were immunized to these fibrosarcomas by surgical tumour removal, cross-reacting tumour-associated transplantation antigens (TATA) were detected on all 3 tumours. Cytotoxic effector cells (CL) were then induced in vitro by co-culture of BALB/c spleen cells with the spontaneous, or one of the carcinogen-induced fibrosarcomas. These CL were shown to be cytotoxic T cells (Tc) and to be directed against cross-reacting TAA on all 3 tumours, by two in vitro 51Cr-release assay systems, direct 51Cr-release cytotoxicity and cellular competitive inhibition of 51Cr release. Further studies demonstrated that the fibrosarcoma TAA involved in in vitro induction of Tc were not present on normal adult or foetal tissues. A secondary cytotoxic response was also detected in vitro when spleen cells from mice immunized to a carcinogen-induced fibrosarcoma were tested. The patterns of cross-reactivity detected by the in vivo and primary in vitro tumour-immune responses suggested that the TAA detected in vivo (TATA) were not identical to the TAA detected in vitro.