Furine Pathway Enzyme Abnormalities in Acute Lymphoblastic Leukemia1

The status of three purine pathway enzymes, adenosine deaminase, 5'-nucleotidase, and purine nucleoside phosphorylase, was evaluated in the leukemic cells of patients with acute lymphoblastic leukemia and correlated with routine immunological cell surface markers. A distinct pattern of enzyme activity was noted in T-lymphoblasts which have significantly higher adenosine deaminase activity (p < 0.02) and lower 5'nucleotidase ( p < 0.001 ) and purine nucleoside phosphorylase (p < 0.01) activities than do non-T, non-B lymphoblasts. This enzyme pattern is similar to that observed in normal human thymocytes but is not shared by the mature, normal T-lymphocytes of peripheral blood, suggesting that it may reflect the differentiation status of malignant T-lymphoblasts. These find ings, which confirm the biochemical heterogeneity of acute lymphoblastic leukemia, may provide an avenue for selective chemotherapy of this disease.