Fluorometric determination of the activity of the biomarker terminal deoxynucleotidyl transferase via the enhancement of the fluorescence of silver nanoclusters by in-situ grown DNA tails.

The activity of terminal deoxynucleotidyl transferase (TdTase) is a biomarker for routine diagnosis of acute leukemia. A method has been developed for the determination of TdTase activity. It is based on the use of silver nanoclusters (AgNCs) whose yellow fluorescence is enhanced by an in-situ grown DNA tail of TdTase-polymerized and guanine-rich DNA at the 3' end of a hairpin DNA. The fluorescence, best measured at excitation/emission peaks of 530/585 nm, increases linearly in the 1 to 35 mU mL-1 TdTase activity range. The detection limit is 0.8 mU mL-1. The method is cost-efficient, selective and convenient. It integrates enhancement of the fluorescence of AgNCs and target recognition into a single process. Graphical abstract Schematic presentation of a method for determination of TdTase activity. It is based on AgNCs fluorescence enhanced by in-situ grown TdTase-polymerized G-rich DNA tail. The method integrates AgNCs fluorescence enhancement and the target recognition into a single process.

A seven-color panel including CD34 and TdT could be applied in >97% patients with T cell lymphoblastic leukemia for minimal residual disease detection independent of the initial phenotype.

A seven-color panel was used to detect minimal residual disease (MRD) in T cell acute lymphoblastic leukemia (T-ALL) via flow cytometry (FCM). Its availability and clinical significance were studied in T-ALL patients with newly diagnosed (n = 64), relapsed (n = 48) and morphologically complete remission (n = 103). The following four features were used to identify immature cCD3+ T cells: CD34+, TdT+, but mCD3-/dim+, and CD45dim+. Among these features, either TdT or CD34 expression was the most useful and were found in 93.8% of patients at diagnosis and 86.7% of patients who relapsed. Although some of the immature markers had disappeared in 23 of 59 cases after therapy, only one case presented with a false negative MRD. Of the 74 consecutive patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT), MRD-positive patients showed a higher relapse rate, a higher cumulative incidence of relapse at 4 years and a shorter median relapse-free survival than MRD-negative patients at post-HSCT(72.7% vs 17.3%, P = 0.000; 100% vs 19.9%, P < 0.0001; and 16 months vs undefined, P < 0.0001). We demonstrated that this panel could be applied to>97% of T-ALL patients to detect MRD and predict relapse after allo-HSCT even in the absence of the initial immunophenotype.

Relevance of immunophenotypes to prognostic subgroups of age, WBC, platelet count, and cytogenetics in de novo acute myeloid leukemia.

Immunophenotyping is one of the independent prognostic factors in acute myeloid leukemia (AML). Relevance of immunophenotypes to prognostic subgroups of age, white blood cells (WBC), platelet count, and cytogenetics in de novo AML was comprehensively investigated in this study for the first time. Human leukocyte antigen (HLA)-DR and CD14 expression associated with the elderly, highest WBC count, and unfavorable-risk cytogenetics; CD4, CD7, and CD11b expression correlated with highest WBC count and unfavorable-risk cytogenetics; CD64 expression was associated with higher WBC count while that of CD13 was associated with lower platelet count; CD22, CD34, CD123, and terminal deoxynucleotidyl transferase (TdT) expression correlated with unfavorable-risk cytogenetics; CD5 expression was associated with normal platelet count while that of CD19 was associated with children and favorable-risk cytogenetics; CD117 expression was associated with low WBC and lower platelet counts; myeloperoxidase (MPO) expression correlated with lower platelet count; and MPO and glycophorin A (Gly-A) expression was associated with lower WBC count and favorable-risk cytogenetics. The results of the relevance analysis revealed the distribution characteristics of antigen expression in different AML prognostic subgroups. The majority of antigens associated with good or poor prognostic subgroups were in accordance with the previous reports of correlation of expression of these antigens with prognosis. Antigens associated with good (or poor) prognostic subgroups were defined as good (or poor)-risk antigens.

Terminal deoxynucleotidyl transferase-positive cells in trephine biopsies following bone marrow or peripheral stem cell transplantation reflect vigorous B-cell generation.

AIMS: Bone marrow is the major site of B-cell generation in humans. While in early childhood a high number of B-cell precursors is found in the bone marrow, only very few such cells are usually detectable in adult bone marrow. To assess the number of immature B cells present after haematopoietic cell transplantation the number of terminal deoxynucleotidyl transferase (TdT)-positive cells in regenerating bone marrow of adult patients was analysed. METHODS AND RESULTS: Bone marrow biopsy specimens were analysed from patients after allogeneic bone marrow transplantation (BMT; n = 14) or stem cell transplantation (SCT; n = 25) and autologous BMT (n = 9). Specimens from 11 untransplanted adult patients and 11 infants were also studied, as negative and positive controls, respectively. Immunohistochemistry was performed on paraffin-embedded bone marrow biopsy sections using TdT as a marker of lymphoid progenitors. Immunoreactivity for CD79a, CD20 and CD10 was used to confirm their B-cell origin. Using computer-assisted automated image analysis we quantitatively assessed the TdT+ cells present. We found a significant increase in the numbers of B-cell precursors in the bone marrow after allogeneic and autologous BMT/SCT compared with adult controls (P = 0.022). To analyse this in detail, we followed some patients after allogeneic BMT/SCT for up to 1445 days, when a marked B-cell increase was still detectable. However, the median number of TdT+ B cells after BMT/SCT was significantly lower than the number of equivalent B cells in infantile bone marrow biopsy specimens (P < 0.001). CONCLUSIONS: Bone marrow of adult patients after BMT/SCT is capable of initiating vigorous precursor B-cell generation, which is not seen in untransplanted adults. However, the increase of immature B cells was variable in our study. Only in two young adult patients did it reach the magnitude of B-cell generation seen in infantile bone marrow where immunocompetent B cells are produced normally. A marked increase in number of immature B cells post-transplant may mimic B-cell acute lymphoblastic leukaemia (B-ALL). This is a potential problem in patients transplanted for B-ALL itself. Since reactive and neoplastic B-cell precursors share the same immunophenotype in paraffin-embedded tissue, additional tools, particularly molecular techniques, may have to be employed to establish the correct diagnosis.

B-cell precursors differentiated from cord blood CD34+ cells are more immature than those derived from granulocyte colony-stimulating factor-mobilized peripheral blood CD34+ cells.

Umbilical cord blood (CB) has been widely used instead of bone marrow (BM) and peripheral blood (PB) for stem cell transplantation (SCT). However, problems of sustained immunodeficiency after CB transplantation remain to be resolved. To elucidate the mechanism of immunodeficiency, we compared the characteristics of B cells differentiated in vitro from CD34+ cells of CB with those of PB. Purified CD34+ cells from CB and PB were cultured on murine stroma cell-line MS-5 with stem cell factor and granulocyte colony-stimulating factor for 6 weeks. The B-cell precursors (pre-B cells) that differentiated in this culture system, were analysed as to their immunoglobulin heavy chain (IgH) variable region gene repertoire and the expression of B-cell differentiation-related genes. CD10+ CD19+ pre-B cells were differentiated from both PB and CB. Although the usages of IgH gene segments in pre-B cells differentiated from CB and PB were similar, the N region was significantly shorter in CB-derived than PB-derived cells. Productive rearrangements were significantly fewer in cells of CB than PB in the third week. Among a number of B-cell differentiation-related genes, the terminal deoxynucleotidyl transferase (TdT) gene was not expressed in CB-derived cells during the culture. These results indicated that immature features of pre-B cells from CB, such as lack of TdT expression, and a short N region and few productive rearrangements in the IgH gene, might cause the delay in mature B-cell production.

Detection of terminal transferase in acute myeloid leukemia by flow cytometry.

The purpose of this study was twofold: (1) to develop an optimized, reliable method for the flow cytometric analysis of the intranuclear DNA polymerase, terminal deoxynucleotidyl transferase (TdT) in acute myeloid leukemia, and (2) to establish the usefulness of a novel, fluorescein-isothiocyanate conjugated monoclonal anti-TdT antibody (HT-6) in double-fluorescence staining for surface antigens in the characterization of leukemic cells. Inclusion of an aldehyde blocking buffer in the staining protocol reduced background fluorescence sufficiently to allow for the detection of the low-level fluorescent TdT+ myeloblasts. When admixed to normal peripheral blood mononuclear cells, 0.4-0.5% of HLA-DR+ or myeloid surface antigen+, TdT+ double-stained myeloblasts could be reliably detected above background levels. Flow cytometric TdT measurements using the HT-6 antibody in 55 patients with TdT+ acute lymphocytic or myelocytic leukemia or blast crisis of chronic myelogenous leukemia were equal or superior to the results obtained with a mixture of monoclonal anti-TdT antibodies (anti-HTDT-Mix) and comparable to those obtained by the conventional slide method employing polyclonal rabbit anti-human TdT antiserum. This flow cytometric TdT determination in combination with surface antigen staining using a novel anti-TdT monoclonal antibody (HT-6) allows for the recognition of minimal leukemic blast cells during clinical remission in acute myeloid leukemia.

Terminal deoxynucleotidyl transferase (TdT) expression in acute myeloid leukemia.

Terminal deoxynucleotidyl transferase (TdT) was initially considered as a marker of immature lymphoid cells, but many studies have since provided conclusive evidence for the existence of TdT+ cases of acute myeloid leukemia (AML). The reported incidence of TdT+ AML cases varies largely (from 0% to 55%, average of combined data of the literature 18%, children 19%, and adults 21%) suggesting interlaboratory differences in the types of AML examined, the sensitivity of the method used, and the percentage of positive blasts taken as cut-off value. Significantly higher frequencies of TdT+ AML were reported in studies employing immunocytochemical staining (alkaline phosphatase anti-alkaline phosphatase or immunoperoxidase) than in series using immunofluorescence microscopy or biochemical assays. Statistical analysis of various cut-off levels demonstrates an inverse correlation between cut-off point and incidence. The combined data show that TdT-positivity is more common in the immature cell types (M0, M1), with no correlation with age or sex. Except for contested suggestions of an association with t(6;9) and t(8;21), no clear relationship between karyotype and TdT status has been documented. Although an association between T-cell receptor or immunoglobulin gene rearrangements and expression of TdT in AML was postulated, subsequent studies could not demonstrate this correlation. There was no significant relationship with other immunophenotypic markers except for CD34 positivity suggesting that the TdT+ cells represent an immature population. The percentage of positive cells was usually lower in AML than in ALL; in most cases only a subpopulation of the AML cells was TdT+. Thus, TdT could be viewed as a marker of hematopoietic immaturity. In about one-half of the studies on adults, TdT expression was reported to indicate a poor prognosis; others did not find any prognostic difference between TdT+ and TdT- AML cases. No correlation between TdT-positivity and prognosis was found in childhood AML.

Purine degradative enzymes and terminal transferase in acute myelogenous leukemia: clinical relevance.

Intracellular adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP) and terminal deoxynucleotidyl transferase (TdT) activities were investigated in adult patients with acute myelogenous leukemia (AML) in order to relate these enzymatic activities to the stage of differentiation and maturation and to the clinical outcome of AML. Both ADA and PNP were measured spectrophotometrically using the method of Hopkinson et al., and TdT was investigated using liquid scintillation technique with slight modification. The level of ADA was above normal in patients with AML whereas the level of PNP and the PNP/ADA ratio were below normal. Short survival was observed in the majority of the patients with markedly increased levels of ADA and decreased levels of PNP and PNP/ADA. Normal patients and patients with AML had no significant differences in TdT activity. Significant differences in ADA, PNP and TdT among AML subtypes were not observed. The levels of ADA and PNP seemed to reflect the clinical severity of this disease.

Usefulness of terminal deoxynucleotidyl transferase as prognosticator in leukemia patients.

Peripheral blood samples from 55 previously untreated leukemia patients (33 males, 22 females) were analysed for terminal deoxynucleotidyl transferase (TdT) activity. TdT was significantly higher in patients with acute myelogenous leukemia (AML; P < 0.001), chronic myelogenous leukemia (CML; P < 0.05) and acute lymphoblastic leukemia (ALL; P < 0.001) when compared with controls. One patient with chronic lymphocytic leukemia (CLL) had undetectable TdT. Among leukemic patients, ALL patients had higher concentration of TdT than CML and AML patients. Females had higher TdT activity than males, although the difference between the two groups was not statistically significant. 68% TdT+ and 32% TdT- patients were in blastic crisis. Patients with more than 10% of blasts in the circulation had significantly higher TdT than blast-negative patients (P < 0.001). No difference in survival was observed between TdT+ and TdT- group. From these results, we conclude that the absolute TdT concentration is of little prognostic value in leukemia patients.

Terminal deoxynucleotidyl transferase positive subpopulations occur in the majority of ANLL: implications for the detection of minimal disease.

A series of 60 acute nonlymphocytic leukemias (ANLL) was analyzed for the expression of terminal deoxynucleotidyl transferase (TdT). The detected TdT+ cells were studied in detail by use of double marker analyses for TdT and differentiation markers, such as myeloid markers (CD13 and CD33), B cell markers, T cell markers, and the precursor antigen CD34. In 15 (25%) of these leukemic cell samples, we found no TdT+ cells or low percentages of CD10+TdT+ cells; the latter probably represent precursor B cells. In the other 45 (75%) ANLL myeloid marker+TdT+ CD10- cells were detected, ranging from 0.1-10% (n = 24) or over 10% (n = 21) of mononuclear cells. Interestingly, a higher frequency of CD34 positivity was found on the TdT+ cells as compared to the TdT- cells, suggesting that the TdT+ cells represent an immature leukemic subpopulation. Therefore, it may be speculated that the TdT+ subpopulation contains the clonogenic ANLL cells. In two patients, in whom immunologic marker analysis was performed at initial diagnosis as well as at relapse, an expansion of the TdT+ subpopulation was documented at relapse, which may reflect a reduced differentiation capacity of the leukemic cells. Previous studies on a series of nonleukemic bone marrow and blood samples revealed that normal counterparts of myeloid marker+TdT+ cells are rare in bone marrow (less than 0.03%, if they occur at all) and that such cells are not detectable in blood. Therefore myeloid marker TdT double stainings may be useful to monitor the TdT+ leukemic subpopulation in patients with a TdT+ ANLL during and after chemotherapy. Our preliminary results on the follow-up of two such patients support this hypothesis.

Enzymes in cancer.

Serum enzyme measurements are not useful in screening for cancer or in primary diagnosis. Just as is the case for other tumor markers, they have an important role in confirming diagnosis and establishing the stage of disease. They also are useful in predicting prognosis and then in following the course of the disease.

Dual rearrangement of immunoglobulin and T-cell receptor genes in blast crisis of CML.

Dual rearrangement of immunoglobulin and T-cell antigen receptor (beta, delta) genes was demonstrated in a case of Philadelphia chromosome-positive chronic myeloid leukemia (CML) in blast crisis. The blast cells, showing L2 morphology and high activity of TdT, expressed pre-B cell (CD19+, Ia+) and myeloid (CD13+, CD34+) surface antigens but lacket T-cell antigens (CD2-, CD7-). Cytogenetic studies on bone marrow and peripheral blood revealed the Phl chromosome in all metaphases analyzed, majority of which also had the additional chromosome changes, +8, +10, +21. Furthermore, molecular analysis of the breakpoint cluster region (bcr) on chromosome 22 showed a rearrangement, confirming the CML origin of the blast cells.

[Terminal deoxynucleotidyl transferase--a marker for lymphatic neoplasms]. / Terminalna deoksinukleotidil transferaza--marker limfatickih neoplazija.

We used the enzymoimmunoassay for quantitative determination of terminal deoxynucleotidyl transferase (TdT) in twenty patients suffering from various hematopoietic and lymphoproliferative diseases. These results were compared to the cytomorphological and cytochemical classification of the diseases. High TdT values were found in all patients suffering from acute lymphatic leukemia, lymphoblastic malignant lymphoma and in case of chronic myeloid leukemia in blastic transformation, whereas negative values of this enzyme were observed in all patients with acute myeloid leukemia, most patients with chronic myeloid leukemia in blastic transformation, those with hairy-cell leukemia and in refractory anemia with blast excess. The aim of this study was to confirm the clinical significance of terminal deoxynucleotidyl transferase as a biochemical marker in differential diagnostics of leukemias and lymphomas.

[Changes in primordial lymphoid organs in chronic glomerulonephritis]. / Izmeneniia pervichnykh limfoidnykh organov pri khronicheskom glomerulonefrite.

Changes in primordial lymphoid organs (bone marrow and thymus) with respect to the content of a serum thymic factor in the blood and specific activity of end desoxynucleotidyltransferase in the bone marrow and peripheral blood were studied in patients with chronic glomerulonephritis with and without the nephrotic syndrome. The mechanisms of autoimmunization were also studied with respect to the presence of renal tissue autoantigen antibodies. Alteration of primordial lymphoid organs was not attended by the autoimmune changes, i.e. production of the renal autoantigen antibodies was not increased. This makes difficult interpretation of the nephrotic syndrome as an autoimmune process and of glomerulonephritis as a whole. Lymphocytes bearing end desoxynucleotidyltransferase more probably participate in the developmental mechanisms of chronic glomerulonephritis.

Terminal deoxynucleotidyl transferase in diagnosis of lymphomas.

TdT activities were determined on 29 specimens of mononuclear blood, bone marrow or lymph node cells from 18 patients with non Hodgkin's Lymphomas, 2 Hodgkin's patients and 3 patients with non neoplastic lymph nodes. The neoplastic cells were typed using tests detecting membrane markers (E, Em, SIg), and monoclonal antibodies (MoAb). In a group of 15 patients with Low Grade Malignant Lymphoma (L. lymphocytic, centrocytic and lymphoplasmocytic) 14 cases belonged to B cell phenotype lymphoma, with 3 cases among them with a moderate TdT activity. In one case of lymphocytic lymphoma the cells had the non T, non B, TdT+ characteristics. High TdT activity was observed in both examined patients with lymphoblastic lymphoma and in cells obtained from the lymph node of one Hodgkin's lymphoma case. Although our group was of heterogenic character, our investigations confirm the value of TdT as biochemical marker of immature lymphocytes and its usefulness for differential diagnosis of malignant lymphomas.

Flow-cytometric detection of terminal deoxynucleotidyl transferase and other intracellular antigens in combination with membrane antigens in acute lymphatic leukemias.

Development of a new fixation procedure allowed flow-cytometric analysis of nuclear and other intracellular antigens in acute lymphatic leukemia (ALL). A short fixation of the cells with buffered formaldehyde acetone (BFA) rendered the cell membrane permeable, allowing the monoclonal antibodies (MoAbs) to penetrate the cell. Through this method, a rapid analysis of intracellular antigens, specific for acute lymphatic leukemia [such as terminal deoxynucleotidyl transferase (TdT), immunoglobulin M (IgM) heavy chain, and antigens recognized by the CD22 or CD3 MoAbs) was performed by flow cytometry. The surface antigens remained intact after this fixation procedure, enabling simultaneous detection of membrane and intracellular antigens. The binding of biotinylated antibodies against several B- and T-lymphoid membrane antigens was detected with streptavidin-phycoerythrin (red fluorescence), whereas the intracellular antigens were stained with FITC-labeled polyclonal antibodies, or indirectly with FITC-labeled goat anti-mouse IgG (green fluorescence). Through this combination of markers, minor cell populations can be detected and a rapid and quantitative immunodiagnosis can be performed.