BETA-N-ACETYLHEXOSAMINIDASES IN THE SPLEEN OF A PATIENT WITH HAIRY-CELL LEUKEMIA

The spleen from a patient with hairy-cell leukaemia had β-N-acetylhexosaminidase activity that could be resolved into three isoenzymes by chromatography on phenyl boronate agarose. Two of these were the major forms, A and B, found in normal tissues but, in addition, there was an 'extra' form that accounted for 15% of total activity. The 'extra' form hydrolysed the synthetic substrate 4-methylumbelliferyl-β-N-acetylglucosamine 6-sulphate, indicating the presence of α-subunits. It was more acidic than A, was less heat-stable and showed no generation of B on denaturation under a variety of conditions. These findings and the immunoblot (Western blotting) analysis demonstrate that the 'extra' form is entirely composed of α-subunits, and most closely resembles S, the residual activity in Sandhoff's disease. © 1990.