Distribution of the carcinoembryonic antigen CEA in gastric lesions. Immunohistochemical testing of three novel monoclonal antibodies.

Three mouse monoclonal antibodies MAB (CEA 12-140-1, -2 and -4) raised against different CEA epitopes were tested in 32 gastric adenocarcinomas (18 intestinal type and 14 diffuse type) and 34 gastric lesions with severe and moderate dysplasia. The MAB stained 13, 11 and 13 out of the 14 diffuse carcinomas and 11, 13 and 13 out of the 18 intestinal carcinomas. The dysplastic lesions were positive in 9, 9 and 6 out of 34 cases. Less than half of the cases with metaplastic epithelium adjacent to the carcinomas were also positive for MAB. All MAB showed the same pattern of reactivity without cross-reactivity. Their cumulative staining rate corresponded closely to that of polyclonal CEA antiserum, but the MAB stained more cells. The reactivity was confined to intracytoplasmic vacuoles in diffuse carcinomas and appeared diffusely in the cytoplasm or limited to the cell membrane in intestinal type of carcinomas. Our findings do not indicate CEA to be a reliable marker for malignant transformation in gastric mucosa.