Cytidine triphosphate synthetase activity in lymphoproliferative disorders

Cytidine triphosphate synthetase (CTP synthetase) activity was measured in extracts from normal and malignant lymphoid cells. A range of enzyme activities was found in the majority of the lymphoproliferative disorders examined, with acute lymphocytic leukemia, nodular poorly differentiated lymphocytic lymphoma, and diffuse histiocytic (large cell) lymphoma (DHL) types exhibiting the widest ranges. It is suggested that CTP synthetase activity is a biochemical marker of the clinical aggressiveness of malignant lymphoma. There was not a close correlation (r super(2) = 0.52) between CTP synthetase and thymidine kinase activities, indicating that other biological factors in addition to cell proliferative rate influence the intracellular CTP synthetase level. Furthermore, in view of the heterogeneity of CTP synthetase activity in leukemia and lymphoma, it is likely that the preexisting enzyme level will be an important determinant of the efficacy of the investigational antileukemic agent 3-deazauridine, which is thought to act by inhibiting CTP synthetase.