The use of hybrid cells in immunotherapy.

HARRIS et. al. isolated somatic hybrid cells (A9/SEWA) between polyoma-induced tumor and mouse fibroblast cell lines. Although these hybrid cells were no longer tumorigenic, we found that their immunogenicity was conserved. It therefore seemed to us that these antigenic, non transplantable, living cells would be an ideal tool for immunotherapy experiments. In our first experiments we assessed the immunoprotection afforded by A9/SEWA cells in both the SEWA tumor/A.SW mouse and C3HPy/C3H mouse systems. However, the efficiency of immunization with hybrid cells is dependent on the stability of the cells, especially in respect to the expression of the TATA. So we also tried to evaluate the immunogenicity as a function of the number of subcultures undergone by the hybrid line. In both systems, the immunogenicity was very good in the early subcultures but, in the C3HPy tumor/C3H mouse system, a loss of immunogenicity was observed as the number of subcultures increased. Thus any clinical application or immunization by hybrid cells would necessitate the verification of the presence of the tumor-associated antigens at each subculture. We are at present experimenting with various in vitro techniques for detection of the expression of these antigens.