The clinical significance of terminal deoxynucleotidyl transferase in leukemia.

Abstract

Terminal deoxynucleotidyl transferase (TdT) activities were assayed in various hematological disorders. High enzyme activities were detected in most cases with acute lymphoblastic leukemia (ALL), in about one third of cases with chronic myelogenous leukemia (CML) in blast crisis and in a few cases with acute myelogenous leukemia (AML). How ever, no significant activities were detectable in other type of leukemia or other hematological disorders. Blasts from two CML cases in blast crisis had high TdT activity and B-lymphocyte surface markers. Blasts in these cases may represent lymphoid precursor cells able to differentiate into both T- and B-lymphocytes or may represent cells closely relatedto pluripotential stem cells. Vincristine-prednisolone (V-P) therapy was very effective in TdT-positive leukemia cases including ALL and CML in blast crisis, while TdT-negative leukemia cases showed poor response to this therapy. Assay of TdT activity in leukemic cells may provide a useful mean for selecting effective therapy and for presuming the origin of blast in leukemia.