Detection of TdT in AML blasts by immunological and biochemical techniques

The cellular level of terminal deoxynucleotidyl transferase (TdT) was measured in blasts from patients with AML. Parallel determinations were made using an immunoassay and polymerizing reaction. There was a good correlation between the two techniques (r = 0.92) and detectable levels of the enzyme was found in approximately 50% of the cases. The TdT levels found in AML blasts were 1/10 - 1/100 of that reported for cells of lymphoid origin.