N-acetyl β-D-glucosaminidase activity in human leukaemia

In order to investigate whether plasma N-acetyl-β-D-glucosaminidase (NAG) activity can provide any diagnostic information in various types of leukaemia, we monitored the activity of this enzyme spectrofluorometrically in plasma samples from 42 leukaemia patients; 20 with acute myelogenous leukaemia (AML); 12 with acute lymphocytic leukaemia (ALL); 10 with chronic myelogenous leukaemia (CML) and 32 normal healthy subjects within the same age group. Mean ± SD NAG activity values in plasma samples of patients suffering from AML, ALL and CML were 10.81 ± 5 U/l, 11.34 ± 4.5 U/l and 7.99 ± 3.75 U/l, respectively. Compared to these data, the NAG value in normal healthy subjects was 5.41 ± 1.15 U/l. Statistical analysis of the data using one way ANOVA and Tukey-HSD test revealed that NAG values in acute leukaemia patients were significantly different (P < 0.05) from those in normal healthy subjects. In order to investigate whether the isoenzyme pattern of plasma NAG in leukaemia patients can provide additional diagnostic information, we subjected some of these samples to ion-exchange chromatography on a DEAE-Sepharose column. Each sample resolved into two isoenzyme peaks (NAG-B and NAG-A). The mean proportion of isoenzyme NAG-B to isoenzyme NAG-A in ALL group of patients was statistically different (P < 0.05) from the mean proportion of these forms in normal healthy subjects. There was no such difference in other groups of patients. Our preliminary data suggest that the plasma isoenzyme pattern of NAG can be of value to differentiate ALL from AML and CML.