Leukemia-induced Alterations of Serum Glycosyltransferase Enzymes¹

Studies on blood group A and H glycosyltransferase enzymes in 54 patients with acute myeloid leukemia were carried out on serum derived from blood samples taken prior to treatment, and in 16 cases, further tests were performed during clinical remission and at the time of relapse. The enzyme assay procedures, using low-molecular-weight compounds as sugar acceptors and radioactive nucleotide sugars as the donor substrates, have been described by Chester et al. (Eur. J. Biochem., 69: 583, 1976). Abnormally low values of H enzyme (expressed as percentage of radioactive sugar incorporated into product; (that is, 1 to 3%) were observed in practically all presentation sera, but the values reverted to normal levels (3 to 15%) at the time of clinical remission and then became low once more with the development of drug resistance and clinical relapse. A enzyme levels measured in presentation sera which had demonstrated abnormal H enzyme were mostly within the normal range. In 2 of 5 A₁ patients' sera and in all of three A₂ patients increases in enzyme levels were observed in remission as compared with presentation serum samples. The depression of biosynthetic enzymes in acute leukemic sera could not be accounted for on the basis of competitive inhibitors or catabolic enzymes. It is proposed that changes of serum glycosyltransferase enzymes reflect alterations in a leukemic cell population and that knowledge of these changes may be of value in prognosis in acute leukemia.