Acute myeloid leukemia: correlation between purine metabolism enzyme activities and membrane immunophenotype

Abstract

A total of 34 AML patients with heterogenous age distribution (from 2 years up to 82 years) were observed. Purine metabolism enzyme activities were compared and correlated with membrane immunophenotype. Analysis of bone marrow and peripheral blood samples based on FAB criteria and immunologic phenotyping of acute myeloid leukemia (AML) provided useful--either confirmatory or contradictory-information on the distribution of M1-M6 patients demonstrating a predominance of M1+M2 and M4 groups (44% and 32.4%, respectively). In contrast, it was demonstrated that less frequent subtypes were M3 and M6 (5.9% and 2.9%, respectively). AML subtypes were correlated with expression of surface antigens detected by the following monoclonal antibodies: CD13, CD33, CDw65, CD11b, CD15, CD14, HLA-DR and CD34. On the basis of immunophenotyping we found the following characteristic markers: M1, M2-CD34, HLA-DR, CD13, CD33, CDw65; M3-CD13, CD33, HLA-DR (negative); M4, M5-CDw65, CD14, CD13, CD33 and HLA-DR. CD14 was confirmed to be a typical marker for discriminating myeloid from monocytoid FAB AML subtypes. Analysis of purine metabolism enzyme activities showed that there is a correlation between the values of adenosine deaminase and purine nucleoside phosphorylase and various immunotypes of AML. High ADA/PNP ratio (> 1.0) was found in M1, M2, M3 subtypes. It was due to the increased level of ADA activity (> 100 pkat.10(-6) cells), though these activities overlapped to a certain extent. It was shown that PNP activity simultaneously decreased. With maturation of cells within AML lineage ADA activity decreased and PNP activity increased. This corresponded with ADA/PNP ratio that was < 1.0 in cells of more mature AML subtypes. We found that the enzymatic values were characteristic mainly in cells of M5 (monocytic) AML subtype and were characterized by decreased values of ADA activity with a simultaneous increase in PNP activity. It follows from our results that ADA/PNP ratio enables to discriminate between myeloid and monocytoid subtypes of AML.