Increased activity of a specific sialyltransferase in chronic myelogenous
leukemia
MA Baker, RN Taub, A Kanani, I Brockhausen and A Hindenburg
Granulocytes from patients with chronic myelogenous leukemia (CML) are
morphologically identical to their normal counterparts but show marked
differences in circulation patterns and in some membrane properties. We
have previously shown that there is abnormal lectin binding to CML
granulocytes, and aberrant sialylation of membrane glycoproteins. To
examine the changes in sialylation of CML granulocytes further, we have
studied membrane preparations from CML and normal granulocytes for specific
sialyltransferase activity. Because sialyltransferase enzymes are specific
for the configuration of the acceptor group, enzyme activity was assayed by
measuring transfer of sialic acid from CMP-14C- sialic acid to substrates
of defined structure. As compared with those of normal counterparts, CML
extracts catalyzed a 50% higher overall rate of sialylation of
asialofetuin, a substrate possessing both N- and O-linked acceptors.
Studies of enzyme specificity utilizing porcine and ovine submaxillary
mucins, antifreeze glycoprotein and alpha-1 acid glycoprotein as acceptors
showed that the increased sialylation by CML extracts was due primarily to
substrates with the O-linked Gal beta 1--- -3GaINAc acceptor group. These
data suggest that sialyltransferase activity is increased in CML
granulocytes compared to normal granulocytes and that the increased enzyme
activity is specific for O- linked Gal beta 1----3GaINAc. This enzyme
activity may be directly responsible for the abnormal membrane sialylation
and pathophysiological behavior of these cells.
Volume 66,
Issue 5,
pp. 1068-1071,
11/01/1985
Copyright © 1985 by The American Society of Hematology
