Terminal transferase in leukemia of adults.

Terminal deoxynucleotidyl transferase (TdT) determinations were carried out on peripheral blood leukocytes or bone marrow cells from 61 adult patients with various types of leukemia. TdT activity was undetectable in the cells of patients with acute myelocytic or acute myelomonocytic leukemia but was present in 12 of 13 patients with acute nonmyelocytic leukemia. None of 3 patients with acute myelocytic transformation of chronic myelocytic leukemia (CML) manifested TdT activity while 4 of 6 patients with lymphoid transformation had such activity. More patients with TdT in their leukemic cells responded to treatment than those without TdT activity. However, our findings suggest that TdT activity may be less useful in management of leukemia than has sometimes been supposed.