Terminal deoxynucleotidyl transferase (TdT) was determined by a biochemical assay in peripheral blood cells of 27 adult patients with acute lymphoblastic leukemia (ALL). Eighteen of 19 patients presenting with a blast cell count higher than 0.5x103/μl were TdT+. Many such cases remained TdT+ when they were restudied during induction therapy or at early relapse, with a blast cell count lower than 0.5x103/μl. In contrast, 8 of 8 patients presenting with 'oligoblastic' leukemia (i.e. with a blast cell count lower than 0.5x103/μl), were TdT-. These results suggested that leukemic cells of patients presenting with a very low blast cell count may have no or very low TdT enzyme activity. Such patients who were disregarded in prior studies, account for about 20% of all ALL cases, and may have a better prognosis.
|Number of pages||9|
|Publication status||Published - 1981|
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