MONOCLONAL-ANTIBODIES DIRECTED AGAINST RAT TRACHEAL EPITHELIAL-CELLS TRANSFORMED INVITRO

Cloned hybridoma cell lines were obtained by fusion of murine myeloma cells with spleen lymphocytes of either F344 rats or BALB/c mice immunized against the malignant F344 tracheal cell line, 2-10-1. Monoclonal antibodies were selected for their ability to bind to the immunizing cell line and not to normal tracheal epithelial cells. Results from quantitative binding assays indicated that such monoclonal antibodies recognized 6 epitopes. Each epitope was detected on 4 other malignant tracheal epithelial cell lines, and was also expressed during early preneoplastic cell passages (i.e., before the cells acquired the ability to produce carcinomas in vivo). Quantitative differences in epitope expression between non-tumorigenic and tumorigenic passages of individual cell lines could not be detected for 5 of the epitope groups. However, two monoclonal antibodies, recognizing the same epitope, did show quantitative binding differences between nontumorigenic and tumorigenic cell passages on 3 of the 5 cell lines tested. Carcinogen-altered tracheal cell population can be distinguished from non-altered cells by use of monoclonal antibodies. This suggests that the antigen expression is an early event associated with the transformation of rat tracheal epithelial cells in culture.