HAVE PREVIOUSLY REPORTED our findings in a study of the p-glucuronidase activity of the white blood cells in adult cases of leukemia and had noted that, in the normal control group, the enzyme level varied from 1000 to 3000 units per gram of buffy coat.' In the cases of adult chronic lymphatic leukemia, the enzyme level was less than 1000 units per gram of buffy coat.
In the present study, conducted in children less than 13 years of age, the diagnosis was for the most part "stem-cell leukemia." N o microscopic differentiation was possible on the basis of morphology.
Forty-six cases were studied, a total of 240 determinations being made during exacerbations and remissions of the disease. The patients were examined before therapy and during therapy with bone-marrow remissions, and determinations were performed during their clinic visits when they had ceased to receive therapy. The method of obtaining the white blood cells was essentially the same as was reported previously. The method was improved in these children, however, in order to be able to separate the white blood cells from 10 cc. or less of whole blood. This blood was drawn into a heparinized centrifuge tube and centrifuged for twenty minutes at 3000 r.p.m. As much buffy coat as possible was withdrawn with a capillary pipette, and the buffy coat resuspended in the patient's own plasma. This second tube was again centrifuged at 3000 r.p.m. for twenty minutes. The plasma layer was discarded and as much buffy coat as possible withdrawn with the capillary pipette and placed in a polyethylene tube sealed at one end. The inside diameter of the tube is 0.07 in.
This tube was centrifuged at 1200 r.p.m. for fifteen minutes and, at the end of this time, there were three distinct layers seen: (1) plasma on the top, (2) buffy coat in the middle, and (3) some red cells at the bottom. The polyethylene tube and contents were quickfrozen by dipping into a mixture of acetone From the