Diagnosis of primary liver cancer using lectin affinity chromatography of serum alkaline phosphatase

Serum alkaline phosphatase (sALP) can be separated into unbound liver type (L-ALP) and bound bone type (B-ALP) by means of WGA affinity chromatography. The L-ALP from the sera of normal adults and various liver diseases was found to show different chromatographic behaviours on DSA affinity column with multiple peaks of ALP activity after the L-ALP was treated with neuraminidase to remove the terminal sialic acids on the sugar chain of L-ALP. The L-ALP from normal sera contained no bound activity on DSA, whereas that from acute or chronic hepatisis, liver cirrhosis and biliary obstruction had a significant amount of bound fractions with weak and intermediate affinity. The strongly bound fraction(s) was only present in the L-ALP serum from primary liver cancer (PLC) and the positive rate of its appearance was 100% in 38 cases of PLC, including 8 alpha-fetoprotein (AFP) negative cases. The WGA chromatography can be skipped and similar results are obtained. The percentage of the strongly bound fraction in serum L-ALP was not related to the level of either sALP activity or AFP, and the appearance of the strongly bound fraction is attributed to the structural difference of sugar chains in L-ALP. Therefore, this L-ALP fraction may be assumed as a new index in the diagnosis of PLC, and the different profiles of sALP or L-ALP on DSA chromatography may be used in the differential diagnosis of benign and malignant liver diseases.