A comparative study of the localization of CEA and NCA2 in cancerous and normal gastrointestinal tissues

The histological localization of CEA in gastrointestinal tissues was re-evaluated after absorption of anti-CEA antiserum with NCA2, another normal antigen cross-reacting with CEA. This absorbed antiserum showed clearly the presence of CEA in colonic tumors and some non-cancerous colonic mucosae, obtained even from non-cancerous patients. In contrast, some of the gastric adenocarcinomas we studied were strained very weakly by absorbed anti-CEA antiserum, although non-absorbed antiserum (or serum absorbed with NCA alone) labelled them strongly. The same difference in reactivity between both antisera was observed in intestinal metaplasia. The localization of NCA2 was studied with a specific antiserum, previously absorbed with CEA and NCA. NCA2 was found to be a noromal cytoplasmic and mucus-associated antigen of gastrointestinal tissues. It was present also in fetal stomach and colon. Sections of gastric and colonic tumors as well as intestinal metaplasia of gastric mucosae always reacted brilliantly with absorbed anti-NCA2 antiserum.