CLASSIFICATION OF CEA-RELATED POSITIVITY IN PRIMARY AND METASTATIC MALIGNANT-MELANOMA

Using a panel of antibodies to carcinoembryonic antigen (CEA), in para ffin-processed biopsy material patchy, predominantly membranous positi vity was seen on tumour cells in 70 per cent of cases of superficial s preading melanoma, 60 per cent of nodular melanomas, and 75 per cent o f secondary deposits studied with unabsorbed polyclonal anti-CEA only. No staining was seen using monoclonal anti-CEAs. Localization of CEA to the cell membrane was confirmed with confocal microscopy. Immunoblo tting of fresh frozen material detected CEA of around 180 kD in both p rimary and metastatic melanomas migrating with an apparent molecular w eight of between 150 and 200 kD, indicating variable glycosylation of the protein. Recognition of an adhesive role for CEA with roles in imm unolocalization and immunotherapy emphasizes the importance of more pr ecise classification of CEA-related positivity in human tumours.