The Development of a Radioimmuno-Assay for Carcino-Embryonic Antigen with some Applications. Clinical Evaluation of Cercino-Ernbryonic Antigen, I

Abstract

Carcinoembryonic antigen (CEA) in serum and urine [human] was estimated by direct radioimmunoassay for CEA in serum and urine (a modified Egan technique). A comparative study of the behavior of CEA batches and anti-CEA antisera from different laboratories in the radioimmunoassay is presented. The incidence of increased serum CEA levels in healthy smokers was related to smoking habits. Assays of CEA in serum obtained by the direct technique and the Hansen perchloric acid-zirconyl gel technique showed comparable results. Various problems affecting the assay of CEA in serum and urine are critically discussed, e.g., criteria for absorbing out of anti-CEA antisera, identification of CEA, factors causing false CEA values, use of reference materials, acceptability of a strict cut-off level to indicated increased CEA levels and factors governing the choice of antisera. In this connection, a new approach which maintains a reliable and consistent cut-off level in follow-up studies is presented. Evidence is presented that urinary CEA is heterogeneous and perchloric acid-unstable.