Differential expression of adenosine deaminase isozymes in acute leukemia.

Total adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) activities were measured in cell samples from 13 cases of de novo acute leukemia and from three cases of chronic myeloid leukemia in blast crisis (CMLBC). These cases could be separated into lymphoid and nonlymphoid types on the basis of enzyme activity, with two misclassifications. However, PNP activity added little or no discriminatory information.

Enzymatic differences between chronic lymphocytic leukemia and prolymphocytic leukemia.

Chronic lymphocytic leukemia and prolymphocytic leukemia of the B-cell immunophenotype are closely related disorders, but differ in their cytomorphologic and clinical features. In an attempt to differentiate further between these two forms of leukemia, we measured adenosine deaminase and purine nucleoside phosphorylase activities by using a linked-enzyme spectrophotometric assay on peripheral-blood leukemic cells from seven patients with chronic lymphocytic leukemia, three patients with prolymphocytic leukemia, and one patient with prolymphocytoid transformation of chronic lymphocytic leukemia. By using discriminant analysis, we were able to distinguish the two groups only on the basis of purine nucleoside phosphorylase activity (F1,9; p less than 0.

Ectopic hormones as tumor markers.

Certain cancers are able to synthesize, store, and secrete peptide hormones. In some cases the hormones possess sufficient biologic activity to produce identifiable paraneoplastic syndromes. Occasionally the measurement of one or more of these hormones in the plasma or serum is clinically useful for monitoring tumor activity.