Differences in the ultrastructural localization of carcinoembryonic antigen in human breast and in colon tumour cells.

The ultrastructural localization of carcinoembryonic antigen (CEA) has been compared in human breast and in human colon tumour cells, utilising immunohistological methods at the electron microscope level. Colon tumours (cell line LS 174 T, and xenografted human colon tumours in nude mice) are characterized by a strong CEA-positivity attached to the outer cell membrane. In contrast, mammary carcinomas (bioptically prepared solid tumours) showed to extracellular membrane - bound labelling. In these tumours, extracellular CEA-localization was mainly found on electron dense bodies.