OVEREXPRESSION OF HUMAN THYMIDINE KINASE MESSENGER-RNA WITHOUT CORRESPONDING ENZYMATIC-ACTIVITY IN PATIENTS WITH CHRONIC LYMPHATIC-LEUKEMIA

The level of cytosolic thymidine kinase (TK1) mRNA in lymphocytes from six healthy people and in lymphocytes from five patients with untreat ed chronic lymphatic leukemia (CLL) was determined with competitive po lymerase chain reaction (competitive PCR). Using this procedure we hav e shown that in patients with CLL, there is an overexpression of TK1 m RNA without corresponding enzymatic activity. The TK1 mRNA level is ap proximately 100-fold higher in lymphocytes from CLL patients than in l ymphocytes from healthy persons. A high level of TK1 mRNA without corr esponding enzyme activity may indicate a defect in the processing of t he enzyme. This may disturb the cells' normal feedback system and ther eby influence the development of malignant conditions.