Expression of hexosaminidase isoenzymes in childhood leukemia

Because differences in hexosaminidase isoenzyme profiles of granulocytes and lymphoyctes suggested that such profiles might help to distinguish between various types of leukemia, was examined leukocyte extracts from 55 untreated children and 12 controls by automated anion-exchange chromatography. In 23 of 27 cases of the common form of childhood acute lymphoblastic leukemia, the activity of hexosaminidase component I was greatly increased; the activity ratio of hexosaminidase I to hexosaminidase A was greater than 0.5 in 18 of these cases, whereas for other types of leukemia and for all normal cells tested, the ratio was less than 0.2. A raised hexosaminidase I was shown to be associated with leukemic cells by the finding of normal isoenzyme profiles of bone-marrow cells from 17 patients in remission who had such an increase either at diagnosis or in relapse. Hexosaminidase isoenzyme analysis had diagnostic value and may provide a new marker for study of leukocyte differentiation.