Tumour Immunity induced in Mice with Cell-free Homogenates of Influenza Virus-infected Tumour Cells

Abstract

THE concept of reinforcing the immunological rejection reaction to a tumour by immunizing the host with tumour cells which have been modified by the introduction of a “helper determinant” onto their surfaces has been reviewed recently¹. In general, tumour specific transplantation antigens (TSTA) on the surface membranes of tumour cells stimulate a relatively weak rejection reaction. If a strongly immunogenic determinant is coupled to the tumour cells, and the cells are then inoculated back into the host, a more intense immune response may be elicited which is also active against the TSTA alone. The helper determinant can be a hapten, a protein, a histocompatibility antigen (introduced into the tumour cell by hybridization with allogeneic cells), or a myxovirus which matures at the tumour cell surface. An early example of the use of a myxovirus as helper determinant is the work of Lindenmann and Klein², who showed that A2G mice could be made immune to challenge with Ehrlich ascites tumour cells by vaccinating them with a cell-free homogenate of tumour cells which had been infected with influenza virus. Vaccination with a mechanical homogenate of uninfected tumour cells was without protective effect. Axler and Girardi³ prevented the expected appearance of tumours in hamsters due to inoculation of newborns with SV40 virus by vaccinating them during the latent period with homogenates of Newcastle disease virus-infected, SV40-transformed hamster tumour cells. Frozen-thawed lysates of non-NDV-infected SV40-transformed cells had no effect. We report here that BALB/c mice can be made immune to challenge with syngeneic, SV40-transformed fibrosarcoma cells by vaccinating them with cell-free homogenates of tumour cells which have been infected with influenza virus. No immunity is induced by vaccinating the mice with homogenates of influenza virus-infected normal cells, or with homogenates of tumour cells not previously infected with influenza virus.