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  • Title: Chromatographic forms of terminal deoxynucleotidyl transferase in normal lymphoid cells and in leukemia cells at presentation and relapse.
    Author: Bell R, Lillquist A, Abelson H, McCaffrey R.
    Journal: Leuk Res; 1982; 6(6):775-80. PubMed ID: 6984113.
    Abstract:
    Normal thymocyte and bone marrow terminal deoxynucleotidyl transferase (TdT) have distinguishing characteristics by phosphocellulose chromatography in Tris buffer: marrow TdT elutes as a single peak at 0.3 M salt, whereas thymocyte TdT separates into two forms, one at 0.3 M salt and one at 0.4 M salt. Since the majority of TdT-positive acute leukemias are anatomically bone marrow-derived, one would have predicted the presence of a bone marrow TdT-phosphocellulose chromatographic pattern in such patients. However, in 376 consecutive, untreated TdT-positive acute lymphoblastic leukemias (ALL) studied by us we have invariably encountered the two-peak thymocyte-type phosphocellulose pattern. The TdT patterns in the thymic-dependent, TdT-positive lymphoma of AKR mice, and the TdT-positive bone marrow-derived, thymic-independent Abelson virus leukemia of Balb/C mice duplicate the situation in human ALL: a thymocyte pattern is seen in both the marrow-derived and thymus-derived diseases. This chromatographic difference between leukemia-associated and normal marrow-associated TdT in both murine and human leukemia suggested that phosphocellulose-TdT patterns might be useful for monitoring residual marrow tumour cell burden in TdT-positive leukemia. This has not turned out to be the case: in eight patients studied in early relapse the blast cell TdT pattern was the single-peak 0.3 M species. Therefore, leukemic cell TdT cannot reliably be distinguished from normal marrow cell TdT. The chromatographic behaviour of TdT may be regulated by phosphorylation-dephosphorylation, the 0.3 M salt peak can be converted to the 0.4 M salt species by treatment with protein kinase and ATP, and the 0.4 M species can be converted to the 0.3 M form by exposure to alkaline phosphatase. Thus, apparently anatomic compartment-specific forms of TdT may only reflect differing cellular metabolic activity.
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