Thymidine kinase and thymidine phosphorylase activities in various types of leukaemia and lymphoma.

Thymidine kinase (TK) isoenzymes and thymidine phosphorylase (TP) activities have been measured in peripheral mononuclear cells of patients with acute lymphoblastic and monoblastic leukaemia or B-chronic lymphocytic leukaemia, as well as in normal subjects, and also in lymph node cells from patients with non-Hodgkin's lymphoma, with Hodgkin's disease and with benign adenopathies. TK1 isoenzyme activity was highest in acute lymphoblastic leukaemia and in centroblastic lymphoma. Then in progressively decreasing order appeared the Hodgkin's disease values, the centroblastic centrocytic lymphoma values and the benign reactive lymph node cell values. When compared to normal blood mononuclear cells, TP was greatly decreased in acute lymphoblastic leukaemia and slightly but significantly decreased in chronic leukaemia. Monoblastic cells exhibited a unique enzyme pattern; moderately increased TK1 activity and high TP activity. Our results suggest that both enzymes are indicative of the maturation status of leukaemic cells from B lineage. They demonstrate that in lymph node cells, TK1 reflects the proliferative status of both malignant and non-malignant cells and that in monoblastic cells the synthesis of dTMP through de novo synthesis is favoured.