Induction of an antitumor immune response in a mouse model after vaccination with B7.1 expressing tumor cells.

The aim of the study was the induction of an antitumor immune response by g enetic modification of tumor cells. This was done by transfecting the costi mulatory molecule B7.1 into a murine tumor cell line SCCVII/SF in order to increase T cell recognition and to install an immunologic memory. One cohor t of immunocompetent mice C3 H/HeN were injected with B7.1 expressing tumor cells, while the control group received parental B7.1 negative tumor cells . In a second step those immunized mice were rechallenged by parental tumor cells and tumor growth was compared to a new control group. Transfection w ith B7.1 prohibits outgrowth of the SCCVII cell line. Animals that have bee n vaccinated in this way are partially immune towards a secondary expositio n to B7.1 negative tumor cells. Outgrowth of this recurrent tumor is slowed down. Such an immunization builds up an immunologic memory. Vaccination wi th B7.1 expressing tumor cells lead to a partial protective tumor immunity in the SCCVII- C3 H/HeN mouse model.