Hexosaminidase I indicates maturation disarrangement in acute leukemias.

For a number of lysosomal hydrolases, abnormally expressed forms have been found to occur in childhood and adult leukemia. Most of these abnormalities are confined to the physicochemical properties of the enzymes, e.g., abnormal electrophoretic mobility, change of isoelectric point, and alteration of isoenzyme pattern. All this has been described for the hexosaminidase system in human leukemia cells. The most-investigated phenomenon is the occurrence of hexosaminidase I [1-3, 5, 6, 19J. Other abnormalities, such as the anodic shift of the Hex A isoenzyme [2, 6] or a relative decrease of the Hex B form [1], are found in various leukemia subtypes. In our study, we found that the Hex I isoenzyme is present in excess in cells from typical cALL, pre B-ALL, AUL, and AML. This has also been described in T-ALL, pre T-ALL, T-CLL, and multiple myeloma cells. However, this isoenzyme has so far not been found to be raised in CML and B-CLL. An anodic shift of Hex A and a decrease in Hex B activity appeared independently in a few cases from among all investigated leukemia forms. In normal leukocytes, hexosaminidases occur in two isoenzymatic variants: Hex A