Comparison of CEA polyclonal antibodies, CEA monoclonal antibodies, tissue polypeptide antigen in the sera of supposedly healthy individuals.
Serum determinations of carcinoembryonic antigen (CEA) using both polyclonal antibodies (PAbs) and monoclonal antibodies (MAbs) were carried out in 348 supposedly healthy screenees. A correlation of the two CEA-detection methods was observed for MAb values higher than 0.5 ng/ml, but not for the lower MAb values that failed to detect CEA. Of 162 such cases (46.5% of the total population that were screened by MAbs), only 39 (11.2%) remained undetected by PAbs, with values as high as 3-4 ng/ml. CEA PAbs thus enabled a more subtle analysis of values in the lower range, a potentially useful factor in screening. In 18 screenees (5.1%) the values were above 2 SD of the mean by MAbs against 13 by PAbs; values above 3 SD were present in three by MAbs and in none by PAbs. In 14 of 18 cases high CEA values were related to smoking and to chronic gastrointestinal disease. The suggested specificity of CEA MAbs for cancer cells thus could not be confirmed because no cancer was detected in this series. Elevated tissue polypeptide antigen values were observed in 14 individuals and were not correlated with either CEA or smoking. Estrogens and estrogen-progestogens were administered to five females whereas four males had gynecomasty, and in three cases leukemia was reported among close relatives.