Carcinoembryonic antigen-like substances in human cavity fluids

Pleural and peritoneal fluids from humans with pathological diseases were examined for the presence of carcinoembryonic antigen-like substances (CEA-LS). Among eight samples tested by a solid phase radioimmunoassay, two pleural fluids and one peritoneal fluid showed significantly elevated CEA-activity. The substances responsible for the CEA-activity were isolated by perchloric acid-extraction followed by two successive Sephadex G-200 chromatography into two pools, Pool I (PI) and Pool II (PII). According to their sedimentation properties, PII was slightly smaller than CEA from tumor tissue-extract (CEA-TTE), while PI was larger than CEA-TTE and approximately twice the size of PII. Micro-double diffusion and antibody binding studies showed that CEA-LS possessed identical antigenic determinants as CEA-TTE, which did not cross-react with normal colon antigen (NCA).