Terminal deoxynucleotidyl transferase and human leukemia

Terminal deoxynucleotidyl transferase activity is as much as several hundred fold greater in acute leukemic lymphoblasts than in unstimulated or phytohemagglutinin stimulated normal lymphocytes, and in leukocytes from other leukemias or from acute lymphoblastic leukemia patients in remission. On the other hand, acute leukemic lymphoblasts and myeloblasts as well as phytohemagglutinin stimulated normal lymphocytes have DNA polymerase activity an order of magnitude higher than that in unstimulated normal lymphocytes, and in leukocytes from chronic leukemias or from acute lymphoblastic leukemia patients in remission. Terminal deoxynucleotidyl transferase thus appears to be a useful index for the detection of leukemic lymphoblasts.