Serum sialyltransferase isoenzyme activities in patients with liver cancer

Serum sialyltransferase (ST) activity has been studied using isoelectric focusing chromatography in normal subjects, in patients with rheumatoid arthritis, and in patients withliver cancers (hepatocellular carcinoma and liver metastasis). The serum which was avoided the contamination of platelet-ST was applied to an isoelectric focusing column containing ampholine (pH 3-10) and the fractions were assayed using asialofetuin as the sialic acid acceptor. Three peaks of ST activity were found in serum from normal subjects at pI 4.40, 6.65 and 7.00. In serum from patients with liver cancer, we found abnormal ST isoenzyme activity at pI 7.90 and 8.30 in hepatocellular carcinoma and pI 7.90 and 8.20 in metastatic liver cancer. These abnormal ST isoenzymes have possibly not sialic acids in their structure. And we did not found the ST activity in sera from patients with rheumatoid arthritis at this pI range.