Purine degradative enzymes and terminal transferase in acute myelogenous leukemia: clinical relevance.

Intracellular adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP) and terminal deoxynucleotidyl transferase (TdT) activities were investigated in adult patients with acute myelogenous leukemia (AML) in order to relate these enzymatic activities to the stage of differentiation and maturation and to the clinical outcome of AML. Both ADA and PNP were measured spectrophotometrically using the method of Hopkinson et al., and TdT was investigated using liquid scintillation technique with slight modification. The level of ADA was above normal in patients with AML whereas the level of PNP and the PNP/ADA ratio were below normal. Short survival was observed in the majority of the patients with markedly increased levels of ADA and decreased levels of PNP and PNP/ADA. Normal patients and patients with AML had no significant differences in TdT activity. Significant differences in ADA, PNP and TdT among AML subtypes were not observed. The levels of ADA and PNP seemed to reflect the clinical severity of this disease.