Lysis of human normal and sarcoma cells in tissue culture by normal human serum: Implications for experiments in human tumor immunology

Sera from 8 of 9 patients with osteogenic sarcoma equally lysed autologous tissue-cultured cells of both skin and osteosarcoma in the presence of complement. Of 155 normal human sera tested, 103 (66%) lysed allogeneic normal skin in tissue culture. These antibodies appeared more prevalent in younger (96% in ages 11-20 yr) than older (33% in ages 41-50 yr) humans. The presence of these "natural" antibodies against normal and malignant cells growing in tissue culture was possibly directed against components adsorbed to the cells during tissue culture or to "new" cell-surface antigens expressed by these cells grown in tissue culture. These non-tumor-related neoantigens on normal and malignant cells in tissue culture represented a potential source of confusion in studies of the serologic response of humans to tumors.