Observations on the synthesis of carcinoembryonic antigen by an established human colonic carcinoma cell line.

Some properties and kinetics of synthesis of the carcinoembryonic antigen (CEA-LoVo) produced by an established human colon carcinoma cell line were analyzed. CEA-LoVo was assayed by the method of Chu and Reynoso which was standardized against the activity of the First British Standard for CEA. CEA-LoVo was stable at -20 and 4 degrees C. At 37 degrees C, CEA-LoVo degraded at the rate of 1.4%/day in cell-free supernatants, and at the rate of 6.6%/day in the supernatants of monolayer cultures. CEA-LoVo was sensitive to enzymatic treatment with trypsin (approximately 55% loss)) and extraction of PCA (> 70% loss). The elution profile of CEA-LoVo in Concanavalin A-Sepharose B coincided with that of the First British Standard for CEA. No A or B blood group antigenic activity was noted. Studies employing immunofluorescent and horseradish peroxidase-labeled antibody techniques demonstrated heavy membrane and moderate intracytoplasmic localization. The greatest amount of net synthesis occurred for cells in the stationary phase while CEA-LoVo release occurred maximally in the lag phase.