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

Cytidine triphosphate (CTP) synthase is one of the key enzymes in pyrimidin e nucleotide anabolic pathways. The activity of this enzyme is elevated in various malignancies including acute lymphocytic leukemia (ALL), In this st udy we investigated the activity of CTP synthase in various human blood cel ls isolated from healthy volunteers by density centrifugation and elutriati on centrifugation. We also investigated the mRNA expression of CTP synthase in lymphocytes and monocytes, The highest activity of CTP synthase was fou nd in thrombocytes (6.48 nmol CTP x mg(-1) x h(-1)), followed by that of mo nocytes (2.23), lymphocytes (1.69), granulocytes (0.52) and erythrocytes (0 .42). The activity of CTP synthase in whole blood samples was at an interme diate level (1.27). The mRNA expression of CTP synthase in monocytes was co mparable to that observed in lymphocytes.