[Neutral alpha-D-mannosidase activity in human granulocytes].

The presence of neutral soluble alpha-D-mannosidase activity was shown in human granulocytes. For detection of the enzyme different methods were used: addition of stabilizing agents; sorption of acid alpha-D-mannosidase on concanavalin A-sepharose; inhibition of acid alpha-D-mannosidase; determination of neutral alpha-D-mannosidase in granulocytes of patients with inherited defect of acid alpha-D-mannosidase (mannosidosis). The specific activity of neutral alpha-D-mannosidase in granulocytes of donors calculated in nmol/min/mg of protein was near to the activity in lymphocytes. However the activity in granulocytes calculated in nmol/min/10(8) of cells was approximately 3 times lower than that in lymphocytes. The activity of neutral alpha-D-mannosidase in immature myeloid cells of a patient with chronic myeloid leukaemia was 10 times higher than in natural granulocytes of the same patient. This high activity may be in connection with the process of cell differentiation or the result of malignant transformation.