Clinical relevance of terminal transferase and adenosine deaminase in leukemia

Terminal Transferase (TdT), Adenosine Deaminase (ADA), immunological membrane markers, cytochemical reactivity and cytogenetics were analyzed in 226 patients with ALL, AUL and AML, in 70 patients with CML and in 3 cases of Ph' positive acute leukemia presenting as ALL. TdT was tested in peripheral blood and bone marrow with both the biochemical and immunofluorescence (IF) methods, and ADA was determined biochemically only in peripheral blood cells. By using conventional cytochemistry, cell surface markers determinations, TdT and ADA analysis, three distinct groups are recognized in ALL at presentation: T-ALL with TdT+ and very high ADA values; non-T, non-B ALL with TdT+ and intermediate levels of ADA; B-ALL with TdT absence and low levels of ADA. Clinical presentation and responses to therapy in adult and children ALL were correlated to TdT determinations. The median survivals in adults, calculated for TdT+ and TdT- groups, were 14.2 and 5.6 months, respectively. TdT and ADA were determined in ALL during remission. The wide fluctuation observed for TdT IF and ADA values prevented a reliable monitoring of remissions. At relapse, TdT and ADA values were similar to those found for ALL at presentation; TdT IF determinations were diagnostic in cases showing CNS involvement as the only localization. Forty per cent of AUL and 11% of AML cases were positive for TdT; the medians of ADA values of the TdT+ cases in both AML and AUL were several times higher than those obtained in the TdT- group. While TdT positivity and high ADA had a favorable prognostic value in AUL, similar conclusions can not be drawn at the moment for AML. In chronic phase of CML, TdT was strictly negative and ADA values were increased over the control line only in cases showing initial signs of transformation. In acute phase, the cases positive for TdT (32%) presented a significantly higher ADA activity than the TdT negative ones. The actuarial survival curves for the TdT+ and TdT- groups differ significantly, presenting median survivals from onset of phase of 11 and 4.8 months respectively. The three cases of Ph' positive ALL were all TdT+, presented high ADA values and entered chronic phase of CML after therapy.