The correlation of adenosine deaminase and purine nucleoside phosphorylase activities in human lymphocytes subpopulations and in various lymphoid malignancies

Abstract

Adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) were measured in normal human and in malignant lymphoid cells. Thymocytes had high ADA activity (21.2 ± 6.8 10 3 nM/h/mg) and low PNP activity (1.2 ± 0.6), whereas T peripheral blood lymphocytes (PBL) had low ADA activity (1.20 ± 0.22) and high PNP activity (2.8 ± 1.3). Moreover cortico-thymocytes had higher ADA and lower PNP levels than medullary thymocytes. A linear correlation was observed between ADA and PNP activities in both thymocytes and T-PBL. Cells from 13 patients with T acute lymphoblastic leukemia (ALL) and 10 patients with T lymphoblastic lymphoma (LL) had very high levels of ADA (respectively 13.0 ± 5.4 and 22.8 ± 14) and low levels of PNP (respectively 1.9 ± 0.8 and 2.5 ± 1.4). However no clear relationship appeared between subgroups of these T-cell malignancies defined by their patterns of surface antigens, revealed by reactivity with monoclonal antibodies, and ADA and PNP levels, and there was no correlation between the two enzymes. In contrast, cells from 31 patients with HLA-DR + common ALL had significantly low values of ADA as compared to cells from six patients with HLA-DR − common ALL and a linear correlation was observed between ADA and PNP in cells from children with non-T, non-B ALL. These results show that specific stages of T-cell development may be characterized by the relationships and the correlation between the two enzymes and suggest that T-ALL and T-LL appear to be the group of lymphoid malignancies with a high degree of incoordination between ADA and PNP activities.