The occurrence of carcino-embryonic antigen-like immunoreactivity in human semen

A substance reacting in a radioimmunoassay for carcino-embryonic antigen (CEA) was found in normal human seminal fluid. It has a mean concentration of 118 ng/ml, it is independent from sperm count and even demonstrable in obstructive azoospermia. Parallelity of dilution curves shows immunologic similarity to the tumor CEA from colon carcinoma. From a gel chromatographic system it is eluted within the same molecular range as iodinated CEA.