Adenosine deaminase (ADA) activity in lymphocytes of normal individuals and patients with chronic lymphatic leukaemia

Clinical significance of serum adenosine deaminase activity in patients with mycosis fungoides

Adenosine deaminase is one of the key enzymes in purine nucleotide degradation. This enzyme exists in most of the human tissues and the activity is high in lymphatic tissues, especially in T lymphocytes. Elevated adenosine deaminase activity in T cell leukemia has been reported, and its inhibitor, deoxycoformycin, has been developed as an antitumor agent. In some types of leukemia, serum adenosine deaminase activity increases in accordance with the severity of the disease. Although mycosis fungoides rarely involves peripheral blood, tumor cells do invade the skin. In order to evaluate the clinical significance of adenosine deaminase in mycosis fungoides, adenosine deaminase activity was measured in sera of 15 patients with mycosis fungoides at various stages. The mean enzyme activity was 23.2 IU/l, which was high with statistical significance compared with healthy controls (P < 0.001). Nine of twelve patients in the plaque stage (T2N0M0, IB) showed higher adenosine deaminase activity than did the normal population. The mean adenosine deaminase activity in sera in the patients in the plaque stage (T2N0M0, IB) was as high as 19.0 IU/l (range 13.7-21.4) with statistical significance compared with healthy control (P < 0.001). Three tumor stage patients without visceral involvement (T3N0M0, IIB) showed higher levels of adenosine deaminase activity (19.7, 21.5, 24.4 IU/l). An erythrodermic patient (T4N0M0, III) also had a high adenosine deaminase activity 28.4 IU/l. Two tumor stage patients with organ involvement (T3N0M1, IVB) exhibited extremely high adenosine deaminase activity (60.9, 32.2 IU/l). The adenosine deaminase activity in sera showed a tendency to become higher with the extension of the stages.(ABSTRACT TRUNCATED AT 250 WORDS)

Patterns of adenosine deaminase, ecto-5'-nucleotidase, poly(A)polymerase and surface light chain expression in chronic lymphocytic leukemias

The levels of activity of three enzymes have been measured in the circulating malignant lymphocytes of 47 patients with B chronic lymphocytic leukemia (CLL). These were the purine degradative enzymes, adenosine deaminase (ADA) and ecto-5'-nucleotidase (5'NT) and the enzyme responsible for the polyadenylation of mRNA, poly(A) polymerase. The patterns of activity of the above enzymes and the expression of surface immunoglobulin light chains were examined. A heterogeneity in the specific activity of the enzymes was observed which could not be attributed to variations of the percentage of B lymphocytes. A positive correlation was found between ADA and poly(A)polymerase activity (r = 0.383, p less than 0.01). Furthermore, the expression of immunoglobulin light chain phenotype was inversely related to 5'NT specific activity; CLL cases in which less than 20% of the cells expressed lambda chain phenotype, presented 5'NT specific activity of 16.7 +/- 3.3 (S.E.) nmol/h/10(6) cells, whereas in CLL cases with more than 20% of the cells expressing this phenotype the enzyme specific activity was 4.8 +/- 1.6 (S.E.) nmol/h/10(6) cells (p less than 0.02). These findings suggest that the simultaneous determination of enzymatic activities and immunological markers, might be useful in defining subsets in CLL and the subsequent clinical treatment.

Combined assay of adenosine deaminase, purine nucleoside phosphorylase, and lactate dehydrogenase in the early clinical evaluation of B-chronic lymphocytic leukemia

The levels of adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), lactic dehydrogenase (LDH), and LDH isoenzyme patterns (LD1 to LD5) have been measured in lymphocyte extract from 28 patients with B-chronic lymphocytic leukemia (B-CLL). The activities of ADA, PNP, and LDH have been correlated with two morphological groups of B-CLL classified according to the percentage of large, nongranular, atypical lymphocytes (AL) in peripheral blood: "typical" B-CLL (less than 10% of AL, 21 cases) and "atypical" B-CLL (10-25% of AL, seven cases). Patients with atypical B-CLL had significantly (P less than 0.001) higher activities of ADA (0.46 +/- 0.17 U/10(9) cells), PNP (1.74 +/- 1.0 U/10(9) cells), and LDH (48.3 +/- 9.7 U/10(9) cells) than patients with typical B-CLL (ADA, 0.29 +/- 0.1 U/10(9) cells; PNP, 0.58 +/- 0.23 U/10(9) cells; and LDH, 29 +/- 10 U/10(9) cells). In addition, the "treatment-free period" was also significantly (P less than 0.025) shorter in the group of atypical B-CLL compared with the typical B-CLL group. No clear-cut statistical differences in lymphocyte surface markers or in several other prognostic factors between the two subgroups of B-CLL were found. The present study supports the idea that in B-CLL the simultaneous determination of ADA, PNP, and LDH might be helpful in better understanding the pathophysiology, prognosis, and natural history of the disease.

A molecular hypothesis concerning the pathogenesis of myasthenia gravis

The purine enzyme, adenosine deaminase, is essential for the maturation of lymphocytes, cell growth and normal immune function. Since adenosine deaminase has the highest activity in the thymus and in T lymphocytes, it is hypothesized that a defective or altered enzyme may be a cause of myasthenia gravis, a lymphoid dyscrasia. It is proposed that the alteration is on the non-catalytic portion of adenosine deaminase concerned with the normal immune function of T lymphocytes. Lymphocytes, particularly suppressor T lymphocytes containing a defective adenosine deaminase will function improperly. They will lose their normal immune regulatory function, allowing immunoglobulin-producing B lymphocytes to produce autoantibodies against the nicotinic acetylcholine receptor, with resultant induction and perpetuation of the autoimmune state. In an attempt to compensate for the defect, there may be hypertrophy of the thymus and lymphoid system, with overproduction of a defective adenosine deaminase. Since many of the functions of thymosin, the alleged active principle in thymus are identical to those of adenosine deaminase, it is postulated that thymosin may be a subunit of adenosine deaminase.

Enzymological studies in chronic lymphocytic leukemia

Adenosine deaminase (ADA), 5'nucleotidase (5'NT), ecto-5'NT, purine nucleoside phosphorylase (PNP), hypoxanthine-guanine phosphoribosyltransferase (HGPRT), adenine phosphoribosyltransferase (APRT), adenosine kinase (AK), AMP-deaminase (AMPD) and adenylate kinase (AdKin) activities were assayed in peripheral blood lymphoid cells from 20 patients with B-cell type chronic lymphocytic leukemia (CLL). Significantly decreased mean activities of ADA, 5'NT, ecto-5'NT, PNP and AMPD were observed when comparing B-CLL lymphoid cells with control peripheral blood lymphocytes (PBL). AK and AdKin activities however, were found to be higher in B-CLL. Relatively wide ranges of ADA and 5'NT activity were observed. In patients with paraproteinaemia, 5'NT activity was found to be relatively high and in the range of the activities in normal PBL. ADA activity seemed to be slightly higher in patients without paraproteinaemia. No correlation could be found between the enzyme activities and the number of cells rosetting with sheep erythrocytes or bearing surface immunoglobulin (sIg). A relationship was suggested between 5'NT activity and Ig production.

Purine metabolism in relation to leukemia and lymphoid cell differentiation

A number of inborn errors of purine metabolism have been associated with immunodeficiency diseases. From studies to the possible mechanism(s) leading to the defects in the immune system, it appeared that the accumulation of deoxyATP and deoxyGTP and the subsequent inhibition of ribonucleotide reductase played an important role. The inhibition of methylation pathways through the accumulation of s-adenosylmethionine seems to be a second valid concept. The amount to which certain subtypes of lymphoid cells were affected by the enzyme deficiencies was strongly related to the enzymatic make-up of the cells. Lymphoid cells from different maturation stages could be affected in a specific way, depending on the different enzyme activities of these cells. Studies on human lymphoblastic leukemias showed that, related to the immunological subtype, the different leukemias could be characterized by a different enzymatic make-up. In this paper we discuss the possibilities for a specific enzyme directed chemotherapy, directed against specific subtypes of human lymphoblastic leukemias. Experimental evidence indicates that for example the adenosine deaminase inhibitor 2'deoxycoformycin can be used as a specific drug against acute lymphoblastic leukemia with the T cell phenotype.

Purine and pyrimidine activities in acute and chronic lymphocytic leukaemia: relation to cellular proliferative status

The cellular levels of the purine catabolic enzymes adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) and those for the pyrimidine activities thymidine phosphorylase and thymidine kinase isozymes have been measured concurrently in peripheral blood nucleated cells of patients with acute lymphoblastic leukaemia, chronic lymphocytic or prolymphocytic leukaemia and correlated with the spontaneous tritiated thymidine uptake of the isolated cells. Highest ADA levels occurred in T-ALL cells but considerable overlap of individual activities occurred for non-T, non-BALL, B-CLL and T-CLL cells. The levels of PNP showed no distinct discriminatory trend in cells of the lymphoid proliferative disorders examined. Thymidine phosphorylase activity was markedly reduced in T-ALL and T-CLL cells with a stepwise increase in the level of mean activities for non-T, non-B ALL, B-CLL and B-PLL cells to that of isolated normal peripheral blood lymphocytes. Spontaneous tritiated thymidine uptake of the abnormal lymphoid cells exhibited a correlation between cellular thymidine kinase isozyme 1 and elevated ADA levels. The use of ADA inhibitors together with thymidine infusion for the treatment of lymphoproliferative disorders is discussed.

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.

Enzyme and membrane markers in leukaemia: recent developments

Terminal deoxynucleotidyl transferase (TdT) assay has proved a valuable test for distinguishing lymphoblastic from myeloblastic leukaemias, particularly in adults whose blast cells are often negative for the c-ALL antigen. The immunofluorescence assay, particularly when used in combination with antisera to surface membrane antigens, has proved a sensitive technique for detecting small numbers of lymphoblasts in extramedullary sites, for example, testis or cerebrospinal fluid, or of residual Thy-ALL blasts in the marrow, which might otherwise be difficult to recognise. Differences in concentration of several enzymes concerned in purine metabolism have been detected between the blast cells in the various acute leukaemias. Adenosine deaminase (ADA) concentrations tend to be higher in Thy-ALL than in other forms of leukaemia, but the wide overlap reduces the diagnostic value of this assay. Thy-ALL blasts, however, appear to be selectively and exquisitely susceptible to inhibition of ADA by the drug deoxycoformycin, which has now been used sucessfully in a number of other wise resistant patients with Thy-ALL to obtain a complete remission. The recently introduced technique for the production of monoclonal antibodies has substantially widened the reagents available for analysing the membrane characteristics of bone marrow stem cells and of cell lineages derived from them. These have revealed previously unsuspected heterogeneity among different cases of acute lymphoblastic leukaemia, for example, among Thy-ALL blasts from different patients, and they have also delineated minor populations of immature thymocytes from which these leukaemic cells are derived. The potential use of these antibodies to prevent graft-versus-host disease by selective removal of T-lymphocytes from donor bone marrow before allogeneic bone marrow transplantation, or to prevent recurrence of Thy-ALL and other lymphoblastic leukaemias or lymphomas by selective removal of leukaemic or lymphoma malignant cells before autologous transplantation, is reviewed.

Nucleoside phosphorylase activity in normal and leukemic cells

Nucleoside phosphorylase (NP) activity was assayed in normal peripheral blood lymphocytes, mature and immature thymocytes fractionated by peanut agglutinability, CLL lymphocytes, and ALL lymphoblasts to determine applicability as an enzymatic cell marker. Circulating lymphocytes had the highest activity, immature thymocytes the lowest, and mature thymocytes were intermediate in NP level. This suggests an increase in NP activity with T-cell maturation. CLL lymphocytes showed very low activity, confirming previous reports. However, the NP activity of the lymphoblasts of 40 patients with B, T, and non-B, non-T ALL was similar to that of normal peripheral blood lymphocytes and could not be used to discriminate between these subgroups of ALL.

Adenine and hypoxanthine metabolism in phythohemagglutinin-stimulated and unstimulated human lymphocytes

The uptake and subsequent metabolism of adenine and hypoxanthine in phytohemagglutinin-stimulated and unstimulated peripheral human blood lymphocytes, freshly prepared or cultured, were studied. To investigate the initial step of nucleic acid metabolism the incorporation of 14C-purines into the acid soluble material was examined. No preferential uptake of adenine or hypoxanthine was observed in freshly prepared and cultured lymphocytes during an incubation of 1 h. However, cultured cells utilized approximately 1/3 of the purines compared to freshly drawn cells. Within the cells 2/3 of adenine and 1/2 of hypoxanthine were metabolized to nucleotides (mainly AMP and ADP). Incubation of lymphocytes with PHA for 1 h produced in the freshly prepared cells an increase of adenine- and hypoxanthine-uptake to 191% and 153%, in 48 h stimulated cells to 158% and 132%. There was, however, no change in the relative rates of the metabolic routes though the intracellular concentrations of nucleotides formed increased with adenine as substrate to 152% and with hypoxanthine to 161% during a 1 h stimulation. In contrast no enhanced formation of acid soluble nucleotide formation could be observed with PHA stimulation during 48 h. The increased rates of purine uptake and metabolism apparent 1 h after addition of mitogen may be due to an altered transport mechanism at the beginning of the transformation as an adaptive response to the increased requirements for the synthetic processes soon to follow. Once the lymphocytes are transformed no demand of purines is necessary and the uptake and metabolism is switched off.

Enzymes of the purine interconversion system in chronic lymphatic leukemia: decreased purine nucleoside phosphorylase and adenosine deaminase activity

Activities of adenosine deaminase (ADA), adenosine kinase (AK), adenine phosphoribosyltransferase (APRT), hypoxanthine guanine phosphoribosyltransferase (HGPRT), and purine nucleoside phosphorylase (PNP), all enzymes of the purine interconversion system, were determined in lymphocytes of 25 patients with chronic lymphatic leukemia (CLL) and in 23 controls. A statistically significant decrease of PNP activities and a reduction of ADA activities at borderline levels were found in the patients, whereas for the other enzymes assayed no deviation from normal values was observed.