Cytochemical demonstration of 5-formyl-tetrahydrofolate cyclodehydrase activity in leucocytes of patients with acute leukaemia.

The activity of 5-formyl-tetrahydrofolate cyclodehydrase has been studied cytochemically in leucocytes of children with acute leukaemia. Comparison of enzymatic activity in the same types of cells showed no significant variation between normal controls and the patients with acute leukaemia. The blast cells were weakly positive or negative.