Isolation from human gastric juice of an antigen closely related to the carcinoembryonic antigen.

A carcinoembryonic antigen-like antigen(s) (CELIA) was isolated from normal human gastric jucie by immunoadsorbents and gel chromatography. The isolated CELIA reacted identically to CEA in immunodiffusion testa against anti-CEA and anti-CELIA. Other experiments suggested subtle differences between CELIA and CEA. Two out of six CELIA preparations tested in immunodiffusion did not react in a completely identical manner with CEA.In gel filtration, CELIA eluted slightly after CEA. Absorption of anti-CEA with CELIA resulted in antisera with greatly reduced reactivity to CELIA, but retained anti-CEA activity. Such antisera may be helpful in attempts to increase the cancer specificity of the CEA test.