Serum deoxythymidine kinase as a progressive marker of hematological malignancy

The levels of serum deoxythymidine kinase (s-dTK) were investigated for 127 patients suffering hematological malignancy by a sensitive method using [125I]-iododeoxy-uridine as substrate. It was found that the deoxythymidine kinase activity in the sera of these patients was higher than the normal levels in adults. It was also found that the levels of s-dTK in the progressive stage were much higher than those in the indolent stage. These results suggest that high levels of s-dTK in hematological malignancy may reflect the extent of disease and that this activity may be derived from proliferating leukemic cells. The deoxythymidine kinase activity in the extracts derived from cultured cell lines and clinical specimens indicated that leukemic cells contained much higher activity than normal cells.