A new method for detecting beta 1,4-galactosyltransferase activity in sera of cancer patients

A new method for assaying the activity of the enzyme that catalyzes the formation of a cancer-associated glycolipid, paragloboside (nLc4Cer), from lactotriaosylceramide (Lc3Cer) and UDP-galactose has been developed that is based on a time-resolved fluoroimmunoassay (TRFIA) with a Europium (Eu)-chelate-labeled antibody. The substrate, Lc3Cer, immobilized on a microtiter plate, was incubated with UDP-galactose, MnCl2, Triton CF-54, and the enzyme. The content of the incubation product, nLc4Cer, was determined by the TRFIA with anti-nLc4Cer monoclonal antibody H-11 as the first antibody and Eu-labeled anti-mouse IgM antibody as the second one. The lower limit of detection of nLc4Cer was estimated to be 0.2 pmol. This method was used to detect the galactosyltransferase activity in sera from patients with colorectal cancer or benign colorectal adenomas and from healthy subjects of a reference sample group. The reference interval was 0-0.25 pmol/25 microliters serum/2 h. Activity was significantly greater in patients with colorectal cancer than in those with colorectal benign adenoma (P < 0.05) and the subjects of the reference sample group (P < 0.01).