Antigen characteristics of nitrosamine-induced urinary bladder cancer in rats

Antigens expressed on urinary bladder cancer cells of transplantation and tissue culture lines, which originated in tumors induced by N-butyl-N-(4-hydroxybutyl)nitrosamine in individual ACI/N rats, were studied by several immunological methods. Tumor-specific transplantation antigen was determined by transplantability of cancer cells into syngeneic rats which had been immunized with the respective cancer cells by the ligation-and-release method. Two out of 6 bladder cancer lines showed high antigenicity but antigenicities of the other 4 lines were of low or undetectable level. Cross resistance was observed in the transplantation immunity among the 2 high antigenic lines but not in the other lines. Cell-mediated cytotoxicity was assayed by the microtestplate method. The lymphoid cells from ACI rats hyper-immunized with cancer cells of a high antigenic line showed a marked cytotoxicity against cancer cells of the immunizing line but not to cells of the other bladder cancer lines including another high antigenic line that induced a cross resistance in transplantation immunity. Tumor-associated cell-surface antigen was detected by membrane immunofluorescence test with serum which was raised in allogeneic Donryu rat by the high antigenic bladder cancer and absorbed with normal ACI rat tissues. The absorbed serum gave positive membrane fluorescence to cancer cells of the immunizing line and 2 other bladder cancer lines but not to cells of other 4 bladder lines and ACI tumors other than bladder cancer. The common antigen detected by the serological method was not reflected either in transplantation immunity or cell-mediated cytotoxicity of the immune lymphoid cells.