Immunoassay of circulating terminal transferase in patients with acute lymphoblastic leukemia: a new technique for diagnosis.

The measurement of circulating terminal deoxynucleotidyl transferase (TdT) antigen can be accomplished by the use of an ELISA immunoassay system. TdT was present in either peripheral or bone marrow plasma of five patients with acute lymphoblastic leukemia (ALL) and absent from normal controls using ELISA. The assay was sensitive to a level of 20 ng/ml. The ALL patient values ranged from 160 ng/ml to 420 ng/ml. Use of ELISA for quantitation of TdT may have important diagnostic implications in patients with ALL.