Cytidine triphosphate synthase activity and mRNA expression in normal human blood cells

Cytidine triphosphate (CTP) synthase is one of the key enzymes in pyrimidine nucleotide anabolic pathways. The activity of this enzyme is elevated in various malignancies including acute lymphocytic leukemia (ALL). In this study we investigated the activity of CTP synthase in various human blood cells isolated from healthy volunteers by density centrifugation and elutriation centrifugation. We also investigated the mRNA expression of CTP synthase in lymphocytes and monocytes. The highest activity of CTP synthase was found in thrombocytes (6.48 nmol CTP x mg(-1) x h(-1)), followed by that of monocytes (2.23), lymphocytes (1.69), granulocytes (0.52) and erythrocytes (0.42). The activity of CTP synthase in whole blood samples was at an intermediate level (1.27). The mRNA expression of CTP synthase in monocytes was comparable to that observed in lymphocytes.