Properties of Carcinoembryonic Antigens

Abstract

As important as this antigen seems to be, little is known about it. It can be detected by its capacity of inducing resistance against the transplanted tumor. The same antigen is probably responsible for several in-vitro reactions: cytotoxic reaction by serum or immune cells, inhibition of in-vivo growth and in-vitro growth in diffusion chambers, colony inhibition, membrane fluorescence. When the reaction induced by this antigen is compared with reactions induced by other transplantation antigens, the transplantation CEA falls into the category of the so-called weak antigens. It is difficult to say whether this antigen exists in normal cells in some undetectable quantity or form (coated, covered, changed, deep inside the cell) or that it appears only after malignant transformation. It is probably coded for by the cell genome, even in virus-induced tumors which contain this antigen. Otherwise, since the same antigen is detectable during embryogenesis, it would be coded for in the embryonic cell by the same virus. The amount and the time of appearance of this CEA during embryogenesis may be important in determining whether the organism will be able to react against the antigen if it reappears in a tumor in the immunologically mature animal. Most antigens which are expressed during embryogenesis are recognized as self and are immunologically tolerated by the organism. This characteristic, however, may not be true for all antigens. First, the inducibility of tolerance seems to be limited in time.