Characterization of in vivo cross-reactive tumor resistance between two cultured murine colon lines

Previous comparative investigations of the in vivo biology of two cultured colon tumors of BALB/c origin, C-C26 and C-C36, demonstrated different biologic activities. To elucidate these differences, the immunogenicity of these lines in providing protection to a subsequent challenge with different doses of tumor cells was investigated. Furthermore, the specificity of this protection was evaluated with cross-protection experiments. The findings demonstrate these lines to be immunogenic and suggest the presence of cross-reactive tumor rejection type antigens on these two cultured colon tumor lines. BALB/c mice immunized with these tumors developed resistance to challenge with the same tumor as well as to challenge with the other colon tumor line. Unexpectedly, BALB/c mice immunized with C-C26 cells and challenged with a syngeneic methylcholanthrene-induced sarcoma, Meth A, exhibited partial resistance to this tumor compared to nonimmunized controls. However, mice immunized with C-C36 cells and challenged with Meth A cells supported the same rate of growth of this tumor as unimmunized controls. These results suggest the presence of at least two different cross-reactive tumor rejection antigens. The first antigen appears to be shared between C-C26 and C-C36 cells while the second antigen may be shared between C-C26 and Meth A. Further definition of these putative antigens could provide us with a better understanding for the diagnosis and treatment of colon tumors.