Abstract
Rabbit antiserum immunized with water-soluble extract of stomach cancer and absorbed with normal human blood plasma and stomach mucosa extract contained a precipitin which reacted not only with the stomach cancer but also with colon cancer extracts. The precipitation reaction was inhibited by both D-glucosamine and D-galactosamine. The absorbed specific antiserum reacted with colon cancer extracts, but not with embryonic tissue extracts. These findings demonstrate an antigenic difference between carcinoembryonic antigen (CEA) and the antigen found in gastric cancers in this study.
The antigenic material eluted after polyacrylamide gel electrophoresis showed a single protein band on disc-electrophoresis and no color developed with alcian blue or formazan staining for glycoprotein, indicating that the antigen found in gastric cancers in this study consists principally of protein. The antigenic substance in the cancer tissue may be excreted into the urine in cancer patients.
