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Erythrocytes contain a high concentration of cytosolic adenosine deaminase and this enzyme activity is present in preparations of stroma-free hemoglobin (SFHS). The documented vasoconstrictor activity of SFHS preparations does not appear to be due to interference with endogenous adenosine-mediated mechanisms, because removal of greater than 80% of adenosine deaminase activity failed to affect the vasoconstrictor potency of SFHS preparations. We have also demonstrated the presence of a contractility-depressant activity in SFHS when the latter was added to aqueous buffer perfusing rat Langendorff-hearts. This activity is diminished in phosphocellulose-purified preparations with reduced adenosine deaminase activity but is not necessarily causally related to this enzyme.

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.

In summary we have shown the following:1) Human erythrocyte ADA has been purified approximately 800,000 fold (sp. act. 538 micronmol/min/mg at 37 degrees) to apparent homogeneity using antibody affinity chromatography. 2) The enzyme was shown to be a single polypeptide chain with estimated molecular weight of approximately 38,000. 3) The 3 electrophoretic forms of erythrocyte ADA purified simultaneously by this technique were indistinguishable by SDS gel electrophoresis under reducing conditions. 4) Several properties of the highly purified ADA were identical to properties observed with an impure preparation of the enzyme.