DNA fragmentation and cell death mediated by T cell antigen receptor/CD3 complex on a leukemia T cell line

An anti-T cell receptor (TcR) monoclonal antibody (mAb), LC4, directed against a human leukemic T cell line, SUP-T13, caused DNA fragmentation ("apoptosis") and cell death upon binding to this cell line. Cross-linking of receptor molecules was necessary for this effect since F(ab')2, but not Fab', fragments of LC4 could induce cell death. Five anti-CD3 mAb tested also caused apoptosis, but only when they were presented on a solid phase. Interestingly, soluble anti-CD3 mAb induced calcium flux and had an additive effect on the calcium flux and interleukin 2 receptor expression induced by LC4, but these anti-CD3 mAb reversed the growth inhibition and apoptosis caused by LC4. The calcium ionophore A23187, but not the protein kinase C activator phorbol 12-myristate 13-acetate (PMA), also induced apoptosis, suggesting that protein kinase C activation alone does not cause apoptosis, although PMA is growth inhibitory. These results suggest that two distinct biological phenomena can accompany stimulation of the TcR/CD3 complex. In both cases, calcium flux and interleukin 2 receptor expression is induced, but only in one case is apoptosis and cell death seen. The signal initiating apoptosis can be selectively prevented by binding CD3 portion of the receptor in this cell line. This difference in signals mediated by the TcR/CD3 complex may be important in explaining the process of thymic selection, as well as in choosing anti-TcR mAb for therapeutic use.

[Anthracycline resistance: cytofluorometric study on infantile lymphoblastic leukemia]

Reduced intracellular drug retention has been recognized as a major characteristic of multidrug resistance (MDR) phenotype in a number of cell line models and has been associated to overexpression of a P-170 membrane glycoprotein. Although many studies have been performed on MDR cell lines, so far only few data have been presented utilizing fresh human tumor cells, leaving open the question of the relevance of reduction of intracellular drug exposure to clinical drug resistance. We chose to utilize blast cell samples obtained from patients with childhood acute lymphoblastic leukemia (ALL) to study their interaction with Doxorubicin (DX) and Daunorubicin (DN) as representative drugs, evaluating cellular drug uptake by flow cytometry. Aim of the work was to check possible difference of anthracycline fluorescence levels in clinically "potentially sensitive" (15 cases) and "potentially resistant" (11 cases) human leukemic blast cells. For this purpose, leukemic cells derived from peripheral blood of patients were exposed in vitro to DX and DN according to different schedules and analyses by flow cytometry. The calculated fluorescence levels associated with the different anthracycline treatment shows a wide interpatient spreading of values. The mean values in the potentially resistant group did not differ significantly from the mean values of the potentially sensitive group at any considered concentration, suggesting that biochemical mechanisms different from that involved in drug transport are responsible for the outcome of clinical drug resistance in childhood ALL.

Pharmacodynamic and DNA methylation studies of high-dose 1-beta-D-arabinofuranosyl cytosine before and after in vivo 5-azacytidine treatment in pediatric patients with refractory acute lymphocytic leukemia

The primary development of clinical resistance to 1-beta-D-arabinofuranosyl cytosine (ara-C) in leukemic blast cells is expressed as decreased cellular concentrations of its active anabolite. Correlations exist between the cellular concentrations of 1-beta-D-arabinofuranosyl cytosine 5'-triphosphate (ara-CTP) in leukemic blast cells and inhibition of DNA synthetic capacity with the clinical response to high-dose cytosine arabinoside (HDara-C). 5-Azacytidine (5-Aza-C) and its congeners are potent DNA hypomethylating agents, an action closely associated with the reexpression of certain genes such as that for deoxycytidine kinase (dCk) in ara-C-resistant mouse and human leukemic cells. Reexpression of dCk could increase the cellular ara-CTP concentrations and the sensitivity to ara-C. A total of 17 pediatric patients with refractory acute lymphocytic leukemia (ALL) received a continuous infusion of 5-Aza-C at 150 mg/m2 daily for 5 days after not responding to (13/17) or relapsing from (4/17) an HDara-C regimen (3 g/m2 over 3 h, every 12 h, x 8 doses). Approximately 3 days after the end of the 5-Aza-C infusion, the HDara-C regimen was given again with the idea that the induced DNA hypomethylation in the leukemic cells may have increased the dCk activity and that a reversal of the tumor drug resistance to ara-C could have occurred. Deoxycytidine kinase (expressed as cellular ara-CTP concentrations) in untreated blasts, DNA synthetic capacity (DSC), and the percentage of DNA methylcytidine levels were determined before and after 5-Aza-C administration. Cellular ara-CTP was enhanced to varying degrees in 15 of 16 patients after 5-Aza-C treatment. The average cellular concentration of ara-CTP determined in vitro by the sensitivity test was 314 +/- 390 microM, 2.3-fold higher than the average value before 5-Aza-C treatment. In 12 patients in whom the DNA methylation studies were completed before and after 5-Aza-C treatment, the average DNA hypomethylation level was 55.6% + 15.8% of pretreatment values (n = 13; mean +/- SD). DSC showed a profound decline in 2/9 evaluable patients who achieved a complete response (CR) after this regimen. The data suggest that treatment with a cytostatic but DNA-modulatory regimen of 5-Aza-C causes DNA hypomethylation in vivo, which is associated with dCk reexpression in the patients' leukemic blasts. The partial reversal of drug resistance to ara-C by 5-Aza-C yielded two CRs in this poor-prognosis, multiply relapsed patient population with refractory ALL.(ABSTRACT TRUNCATED AT 400 WORDS)

Adhesion molecules of cultured hematopoietic malignancies. A calcium-dependent lectin is the principle mediator of binding to the high endothelial venule of lymph nodes

This study documents that a calcium-dependent phosphomanosyl-binding site on human lymphoid malignancies mediates attachment to the peripheral node high endothelial venule (PNHEV). The phorbol ester PMA coordinately upregulates lectin activity and binding to the PNHEV in the human T-lymphoblastic cell line Jurkat but not in the less phenotypically mature lines HSB2, Molt4, CEM, and HPB-ALL. In contrast, expression of CD18, CD2, and several common epitopes of the putative adhesion receptor gp90Hermes (CD44) did not correlate with attachment to PNHEV in this series of cell lines. Insensitivity to inhibition by the CD18 MAb TS 1.18, temperature and divalent cation requirements further distinguish the Jurkat-PNHEV adhesive interaction from CD11a/18- and CD2-mediated adhesion. The PMA-induced phenotypic changes in the Jurkat line parallel late thymocyte differentiation as well as lymphocyte activation, suggesting that expression of the endothelial-binding lectin may be linked to one or both of these processes. The lectin-like activity on Jurkat cells is functionally indistinguishable from those previously linked to PNHEV recognition in normal human lymphocytes, normal rat lymphocytes and both normal and malignant murine lymphoid cells. In the mouse, this activity is either contained in or functionally linked to a member of the LEC-CAM family gp90Mel14, suggesting that Jurkat cells express the human homologue of the murine nodal homing receptor. Thus cultured T lymphoblastic malignancies express a variety of potential endothelial adhesion molecules but use primarily a highly conserved surface lectin to interact with PNHEV.

Atypical multidrug resistance in a therapy-induced drug-resistant human leukemia cell line (LALW-2): resistance to Vinca alkaloids independent of P-glycoprotein

Near diploid leukemic T-cells (LALW-2), exposed to cytotoxic drugs only as a consequence of therapy administered to the donor patient, have been maintained by serial xenograft in nude mice. In comparison with the leukemic line CCRF-CEM, using a growth inhibition assay, LALW-2 cells were resistant to Vinca alkaloids and actinomycin D (relative resistance, 200-fold or more), were slightly resistant to Adriamycin (relative resistance, 4-fold), and showed no resistance to daunorubicin or teniposide. By comparison, a vincristine-resistant CEM subline developed in our laboratory (CEM/VCR R) was resistant to all these agents by at least 30-fold. The VCR R subline served as a positive control, confirming the previously reported correlation between multidrug resistance and amplification of the P-glycoprotein gene. Comparison of CEM, CEM/VCR R, and LALW-2 cells establish that the P-glycoprotein gene was not amplified or overexpressed in the LALW-2 cells; neither could the gene product be detected by immunoblotting in extracts from these cells. The LALW-2 cells were further distinguished from CEM/VCR R cells due to the lack of increased vincristine efflux by the xenografted cells, an effect readily demonstrable in the CEM/VCR R cells. However, although LALW-2 cells efflux vincristine at the same rate as CCRF-CEM cells, the xenografted cells exhibited a reduced rate of vincristine accumulation. Uptake of daunorubicin by LALW-2 cells was not distinguished from that by CEM cells, consistent with similar 50% inhibitory dose levels for this drug in both cell populations, and differentiating both from CEM/VCR R cells. Thus, clinical resistance in this case appears to be an "atypical" form of multidrug resistance specifically distinguished by resistance to Vinca alkaloids and actinomycin D occurring in the absence of increased amounts of P-glycoprotein and manifesting decreased drug uptake.

Identification of H- and L-ferritin subunit binding sites on human T and B lymphoid cells

Monoclonal antibodies to the H and L subunits of ferritin were used in indirect immunofluorescent studies to investigate the subunit specificity of ferritin binding to transformed T and B lymphoid cell lines. Pre-incubation of cells with recombinant H ferritin followed by antibodies to the H subunit produced a labelling pattern in which all cells showed strong fluorescent stippling. Corresponding experiments with liver ferritin and an antibody to the L subunit revealed that most cells were lightly stippled, but 3-5% of the cells were intensely labelled. These two labelling patterns were distinct as assessed by cross-blocking experiments with recombinant H and liver ferritins. These results imply that different binding sites exist for each subunit.

Flow cytometric evidence for minimal residual disease and cytological heterogeneities in acute lymphoblastic leukemia with severe hypodiploidy

Two subpopulations of small and large leukemia cells and binucleated cells were present in the bone marrow of a 10-year-old girl with acute lymphoblastic leukemia (ALL). Cytogenetic studies showed some cells with a karyotype of 34,X,-X,-2,-3,-4,-5,-7,-9,-13,-15,-16,-17,-20, and others with a karyotype that was exactly double the chromosome set in the cells with 34 chromosomes. Flow cytometric (FCM) examination of surface common ALL antigen (CALLA) and DNA content of the lymphoblasts led to the identification of the primary hypodiploid DNA stemline (DI = 0.72), which corresponds to the small-sized blasts, and the secondary hyperdiploid DNA stemline (DI = 1.44), which corresponds to the large-sized blasts. Sequential bone marrow examinations with FCM and cytogenetics revealed the persistence of the primary hypodiploid clone during remission and their proliferation with chromosomal evolution at full relapse. These results suggest that more rational inductive therapy should be designed to achieve the favorable outcome of ALL with severe hypodiploidy and that FCM is a useful tool to monitor the minimal residual disease of this subgroup in ALL.

Binding properties and proliferative effects of human recombinant granulocyte-macrophage colony-stimulating factor in primary leukemia and lymphoma

Binding of radiolabeled human granulocyte-macrophage colony-stimulating factor (GM-CSF) was studied with blast cells from eight patients with acute myeloblastic leukemia (AML), and neoplastic lymphoid cells from one patient with acute lymphoblastic leukemia (ALL), two patients with chronic lymphocytic leukemia (CLL) and one patient with undiagnosed B cell neoplasia. In all AML cases studied, Scatchard graphs of the direct binding data were curvilinear, and were best fitted by curves derived from a two-binding-site model; one site with high affinity (Kd1 = 12-71 pM; 174-602 sites/cell) and the other with low affinity (Kd2 = 0.5-2.7 nM; 1137-6020 sites/cell). A cross-linking study on blast cells from one AML patient demonstrated specific bands which were similar to those reported for peripheral blood neutrophils. Furthermore, blast colony assays for the same preparations showed remarkable proliferative response to GM-CSF in the concentration range from 0.3 nM to 7.0 nM (ED50 greater than 0.7 nM). This concentration range is approximately one order of magnitude higher than that which is effective for colony formation from normal bone marrow progenitors (ED50 in equilibrium 0.1 nM). No significant correlation could be observed between the responsiveness of blast progenitors to GM-CSF, and the numbers or affinities of GM-CSF binding sites demonstrated on blast cells. In studies with neoplastic lymphoid cells from four patients, 125I-GM-CSF also specifically bound in two cases, while response to GM-CSF was not observed in these cases. These results indicate that the expression of GM-CSF receptor is not restricted to the GM-CSF-responsive AML blast cells, but can be observed in other AML blast cells and even in neoplastic lymphoid cells.

Two distinct affinity binding sites for IL-1 on human cell lines

We used two human cell lines, NK-like YT-C3 and an EBV-containing B cell line, 3B6, as models to study the receptor(s) for IL-1. Two distinct types of saturable binding sites were found on both cell lines at 37 degrees C. Between 1 pM and 100 pM of 125I-IL-1-alpha concentration, saturable binding sites were detected on the YT-C3 cells with a K of 4 x 10(-11) M. The K found for the IL-1-alpha binding sites on 3B6 cells was 7.5 x 10(-11) M. An additional binding curve was detected above 100 pM on YT-C3 cells with a K of 7 x 10(-9) M and on 3B6 cells with a K of 5 x 10(-9) M. Scatchard plot analysis revealed 600 sites/cell with high affinity binding and 7000 sites/cell with low affinity for YT-C3 cells and 300 sites/cell with high affinity binding and 6000 sites/cell with low affinity for 3B6 cells. At 37 degrees C, the internalization of 125I-labeled IL-1 occurred via both high and low affinity IL-1R on both YT-C3 and 3B6 cells, whereas the rates of internalization for high affinity binding sites on YT-C3 cells were predominant in comparison to that of low affinity binding sites. In chemical cross-linking studies of 125I-IL-1-alpha to 3B6 and YT-C3 cells, two protein bands were immunoprecipitated with Mr around 85 to 90 kDa leading to an estimation of the Mr of the IL-1R around 68 to 72 kDa. In similar experiments, the Mr found for the IL-1R expressed on the murine T cell line EL4 was slightly higher (around 80 kDa). Whether these distinct affinity binding sites are shared by a single molecule or by various chains remains to be elucidated.

Induction of tumoricidal activity and alterations of growth by interleukin-2 and manipulation of protein kinase C and cytosolic calcium in childhood acute lymphocytic leukemia cells

Signals from many receptor-ligand interactions are mediated by enhancement of phospholipid hydrolysis which generates metabolic intermediates stimulating protein kinase C (PKC) and elevating cellular calcium. Pharmacologic agents such as phorbol 12, 13-dibutyrate (PDBu) and ionomycin selectively stimulate PKC and elevate intracellular calcium to directly stimulate downstream mechanisms critical to cell growth and function. This study examines the effects of PDBu, ionomycin, and rIL-2 on childhood ALL blasts of early B lineage with respect to various aspects of cell activation, including DNA synthesis, induction of non-MHC restricted tumoricidal activity, and changes in morphology and phenotype. Five childhood ALL samples were tested. A marked heterogeneity was seen among the ALL samples with respect to in vitro growth following manipulation with PDBu, ionomycin, and/or rIL-2, whereas normal peripheral blood lymphocytes (PBL) were consistently stimulated to grow with the combination of PDBu and ionomycin. Growth responsiveness did not appear to correlate with morphologic or phenotypic classification of the leukemia samples. Four of the five leukemia samples developed substantial non-MHC restricted cytotoxicity to K562 (natural killer cell (NK) sensitive) and Daudi (NK resistant) targets in response to rIL-2. This functional cytotoxic response correlated with morphologic changes in the cells and the appearance of granules. Phenotypic analyses of the ALL samples at the time of their peak cytotoxic function were consistent with the fresh ALL phenotype and showed no major change in cell populations. Three of the five ALL samples also retained rIL-2 induced cytotoxic capabilities when exposed simultaneously to the combination of PDBu and ionomycin, whereas rIL-2 induced tumoricidal activity in normal PBL and bone marrow cultures was inhibited by these reagents. These data show that morphologically and phenotypically similar ALL blasts have heterogeneous proliferative responses to the PKC and calcium modulators PDBu and ionomycin, as well as to rIL-2. Cytotoxic responses are also different from those of normal PBL and bone marrow cells with respect to kinetics and responsiveness to inducing agents. Thus current morphologic and phenotypic classifications of ALL may not adequately reflect the heterogeneity of this disorder as described here.

Energy metabolism in children with newly diagnosed acute lymphoblastic leukemia

The effect of tumor burden in acute lymphoblastic leukemia on resting energy expenditure, thermic effect of food, and substrate utilization was investigated with open-circuit indirect calorimetry after an overnight fast. Nine patients (six females, three males) ages 6.5 to 15.8 y were studied. Patients were divided into two groups according to their tumor burden at diagnosis (i.e. white cell count, presence or absence of mediastinal mass, or massive organomegaly). The patients with a greater tumor burden had increased energy expenditure. Their resting energy expenditure returned to normal in response to chemotherapy. These results must be interpreted with caution due to the small patients numbers (high tumor burden n = 3; low tumor burden n = 6). Substrate utilization was altered by chemotherapy with an increase in carbohydrate utilization and a decrease in fat oxidation (p less than 0.009). The magnitude of the thermic effect of food tended to increase on treatment (p less than 0.016). Inasmuch as most chemotherapy programs for children last up to 3 y, we believe it is important that the effects of chemotherapy on intermediary metabolism be studied, particularly in relationship to any possible permanent effects on growth and development.

Discrimination of tuberculous from carcinomatous pleural effusion by biochemical markers: adenosine deaminase, lysozyme, fibronectin and carcinoembryonic antigen

We measured adenosine deaminase (ADA), lysozyme, fibronectin and carcinoembryonic antigen (CEA) in the pleural fluid of tuberculous and carcinomatous pleural effusion in order to discriminate these two groups. Tuberculous pleural effusion had significantly higher levels of ADA and lysozyme than did carcinomatous effusion. When ADA activity of more than 33 IU/l is considered, diagnostic tests of tuberculous effusions showed a sensitivity of 100%, specificity of 95% and accuracy of 96%. A pleural fluid/serum ADA ratio (pl-ADA/s-ADA) above 1.1 was found in 100% of tuberculous and in 53% of carcinomatous effusions (sensitivity 100%, specificity 47%, diagnostic accuracy 70%). A lysozyme level above 12 micrograms/ml, selected as the discriminating limit, was found in 100% of tuberculous and in 17% of carcinomatous effusions (sensitivity 100%, specificity 83%, diagnostic accuracy 88%). Pleural fluid/serum lysozyme ratio (PL/SL) was also valuable in the discrimination of these two groups. When the cut-off level of 1.2 was considered, diagnostic tests of tuberculous effusions showed a sensitivity of 100%, specificity of 88% and accuracy of 93%, respectively. The mean fibronectin concentration in pleural fluid with tuberculous effusion was significantly higher than that in carcinomatous effusion, but there was a marked overlap between these two groups. On the other hand, CEA was significantly higher in carcinomatous effusions than in tuberculous effusions. At a cut-off level of 5 ng/ml, 53% of patients with carcinomatous effusion showed elevated pleural fluid CEA levels, while none of the tuberculous effusion did (sensitivity 53%, specificity 100%, diagnostic accuracy 65%).(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructural detection of RNA in leukemic cells by the RNase-gold method

We analyzed semiquantitatively the ultrastructural distribution of RNA by the RNase-gold method in 40 patients with acute leukemia (20 patients with AML and 20 with ALL) before the initial treatment. The number of gold particles showing the presence of RNA was high in the granular component of the nucleolus and cytoplasm but low in the fibrillar component of the nucleolus, granules, the Golgi area, and Auer bodies. The number of gold particles in the nucleolus, nucleus, or cytoplasm was higher in AML than in ALL (p less than 0.01). The RNase-gold method seems to be useful for evaluating the capacity of protein synthesis, maturity, or differentiation of leukemic cells.

Development of resistance to 1-beta-D-arabinofuranosylcytosine after high-dose treatment in childhood lymphoblastic leukemia: analysis of resistance mechanism in established cell lines

Cell lines PER-163 and PER-164 are derived from a patient with acute lymphoblastic leukemia who developed resistance to 1-beta-D-arabinofuranosylcytosine (ara-C) after high-dose (HD) therapy. Both lines are highly resistant to ara-C and have maintained stable resistance for more than 18 mo. The resistance in PER-164 cells is the result of a selection process in vivo only, while PER-163 cells have in addition been exposed to ara-C in culture. Comparison with cell line PER-145, which is sensitive to ara-C and was established from the same patient before HDara-C therapy, revealed no differences with respect to surface markers, morphology, cytochemical stains, or requirements for growth in vitro. The leukemic origin of the three cell lines is indicated by the close similarities of all three cell lines to the patient's fresh cells. The analysis of the two resistant cell lines shows that resistance to ara-C is not due to lower ara-C transport capacity nor to cytokinetic reasons, since the percentage of cells in S-phase is similar in all three cell lines. In addition, the resistant cell lines do not show any increased cytidine deaminase activity. PER-164 cells show a markedly reduced deoxycytidine kinase activity, 4.8 nmol/h/mg of protein, compared to PER-145 cells with an enzyme activity of 21.48 nmol/h/mg of protein. In PER-163 cells, no deoxycytidine kinase activity could be detected. Furthermore, the two resistant cell lines show significantly different dCTP levels. The sensitive PER-145 cells generated 97.9 pmol of 1-beta-D-arabinofuranosylcytosine triphosphate (ara-CTP)/10(7) cells during a 45-min incubation period in the presence of 10(-6) M ara-C. This contrasts with 0.16 and 12 pmol of ara-CTP/10(7) cells for PER-163 and PER-164 cells, respectively. These investigations suggest that cell phenotypes with distinct features can be generated after HDara-C treatment and that decreased deoxycytidine kinase activity appears to be one of the major mechanisms of resistance.

Hepatic drug clearance in children: studies with indocyanine green as a model substrate

For several drugs metabolized by the liver, higher dosages (mg/kg body weight) are required in children to attain serum concentrations comparable to those in adults. Indocyanine green (ICG), a commonly used model substrate for hepatic elimination of high intrinsic clearance drugs, has been extensively evaluated in adults but not in children. We evaluated the disposition of ICG in 115 children with leukemia and nine healthy adult volunteers. The mean (SD) ICG plasma clearance (CLp) for all 115 children (age 0.9-17.8 years) was significantly greater (p = 0.0006) than for adults [14.8 (7.8) versus 10.6 (2.4) mL/min/kg]. When clearances from only children less than 10 years of age (N = 85) were compared with those from adults, the difference was even greater [15.6 (7.3) versus 10.6 (2.4) mL/min/kg; p = 0.0001]. However, when ICG CLp was normalized to body surface area, values for children did not differ significantly from adults [378 (204) versus 422 (102) mL/min/m2]. These data provide insight as to why dosage (mg/kg) requirements of certain drugs are higher in children.

Expression of the three myeloid cell-associated immunoglobulin G Fc receptors defined by murine monoclonal antibodies on normal bone marrow and acute leukemia cells

Monoclonal antibodies (MoAbs) have been prepared recently that recognize the three cell-surface receptors for the Fc portion of immunoglobulin (Ig), termed Fc gamma RI (MoAb 32.2), Fc gamma R II (MoAb IV-3), and Fc gamma R III (MoAb 3G8) that are expressed on selected subsets of non-T lymphocyte peripheral blood leukocytes. In the blood, Fc gamma R I is expressed exclusively on monocytes and macrophages, Fc gamma R II on granulocytes, mononuclear phagocytes, platelets, and B cells, and Fc gamma R III on granulocytes and natural killer (NK) cells. We have examined the expression of these molecules on normal bone marrow (BM) cells and on leukemia cells from the blood and/or BM in order to determine their normal ontogeny as well as their distribution on leukemic cells. BM was obtained from six normal volunteers and from 170 patients with newly diagnosed acute leukemia. Normal BM cells were found to express Fc gamma R I, II, and III with the following percentages: 40%, 58%, and 56%, respectively. Cell sorting revealed that both Fc gamma R I and Fc gamma R II were detectable on all subclasses of myeloid precursors as early as myeloblasts. Cell sorting experiments revealed that 66% of the granulocyte-monocyte colony-forming cells (CFU-GM) and 50% of erythroid burst-forming units (BFU-E) were Fc gamma R II positive with only 20% and 28%, respectively, of CFU-GM and BFU-E were Fc gamma R I positive. Acute myeloid leukemia (AML) cells expressed the three receptors with the following frequency (n = 146): Fc gamma R I, 58%; Fc gamma R II, 67%; and Fc gamma R III, 26% of patients. Despite the fact that Fc gamma R I is only expressed on monocytes among blood cells, AML cells without monocytoid differentiation (French-American-British [FAB]M1, M2, M3, M6) were sometimes positive for this receptor. However, Fc gamma R I was highly correlated with FAB M4 and M5 morphology (P less than .001). Fc gamma R II was also correlated with FAB M4 and M5 morphology (P = .003). Cells from 11 patients with acute lymphoblastic leukemia were negative for Fc gamma R I, but six cases were positive for Fc gamma R II and III (not the same patients). These studies demonstrate that Ig Fc gamma R are acquired during normal differentiation in the BM at or before the level of colony-forming units. In addition, we show that acute leukemia cells commonly express Fc gamma R.

Identification of a membrane-associated folate-binding protein in human leukemic CCRF-CEM cells with transport-related methotrexate resistance

CEM/MTX cells, a subline of CCRF-CEM cells resistant to methotrexate (MTX) by virtue of impaired transport by the reduced folate/methotrexate transport system, were grown in media containing folate levels in the physiological range rather than in standard media supplemented with high folate concentrations. Over a 7-month period folic acid concentrations were gradually lowered from 2 microM to 2 nM without subsequent changes in the transport-defective phenotype. In these cells we observed the up regulation of a membrane-associated folate-binding protein with high affinities for folic acid and reduced folates, but poor affinities for the folate antagonists MTX and 10-ethyl-10-deazaaminopterin. The binding capacity for [3H]folic acid was 12.5 pmol/10(7) cells, but could be further increased to 30 pmol/10(7) cells following cell transfer to completely folate-deficient medium for 3 days, except that in the latter situation cell growth stopped. The affinities of the folate-binding protein for 5-methyltetrahydrofolate, folinic acid, and MTX were 0.33, 0.11, and 0.009, respectively, relative to that of folic acid. Growth of CEM/MTX cells was promoted by nanomolar concentrations of either folic acid (median effective concentration, 0.35 nM) or folinic acid (median effective concentration, 0.75 nM), suggesting that the folate-binding protein is not only involved in folate binding, but also in the uptake of folates. The insensitivity of CEM/MTX cells to MTX was correlated with the poor affinity of the folate-binding protein for MTX, compared to folic acid. MTX was only growth inhibitory when added at concentrations at least 30-fold exceeding those of folic acid in the culture medium. On the other hand, CEM/MTX cells grown at 2 microM or 2 nM folic acid were equally sensitive to the lipophilic antifolate trimetrexate. Despite the low affinity for MTX, the folate-binding protein could be specifically labeled by an N-hydroxysuccinimide ester of [3H]MTX and appeared to have a molecular weight of 44,000 as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These data suggest that an alternative folate uptake system, a folate-binding protein, car play an important role in transport-related methotrexate resistance. Moreover, since all these effects were observed for CEM/MTX cells grown at folate levels in the physiological range, it is conceivable that this mechanism of methotrexate resistance can also be of significance in leukemic cells in vivo.

Mineral homeostasis and bone mass in children treated for acute lymphoblastic leukemia

Clinical observations of bone pain, abnormal gait, and unusual fractures during remission of leukemia led us to assess mineral status in a cohort of 16 children with acute lymphoblastic leukemia treated with intensive chemotherapy. During maintenance and 6 months after the completion of therapy, blood and urine were analyzed for calcium and magnesium and blood for osteocalcin, vitamin D, and parathyroid hormone. Bone mineral content and bone width of the distal one third of the radius of the nondominant arm was measured by single-photon absorptiometry. During therapy, mild ionic hypocalcemia (less than 1.19 mmol/L) and hypomagnesemia (less than 0.77 mmol/L) were demonstrated in 9 and 8 of 16 children, respectively; hypercalciuria (8/16) and hypomagnesiuria (12/16) were also observed. Plasma osteocalcin values correlated with plasma magnesium levels (r = 0.54; p less than 0.05). Oral magnesium supplements normalized plasma magnesium, calcium, and osteocalcin levels, all of which were normal at the postchemotherapy study. Plasma 1,25-dihydroxyvitamin D levels were nondetectable (less than 8 ng/ml) in 12 of 13 patients receiving therapy and in 7 of 14 patients not receiving therapy; alkaline phosphatase activity increased significantly after therapy (179 +/- 86 to 340 +/- 101 units/L), and parathyroid hormone levels were normal in both studies. Bone mineral content/bone width ratio was less than 1 SD below the mean for age- and sex-related population standards in 70% of patients. These data indicate that alterations in magnesium, calcium, and vitamin D metabolism in children treated for acute lymphoblastic leukemia may be instrumental in inducing or sustaining altered bone turnover during chemotherapy.

The transport of pteridines in CCRF-CEM human lymphoblastic cells

The transport routes used by CCRF-CEM human lymphoblastoid cells for the influx and efflux of unconjugated pteridines were analyzed using [3H]6-hydroxymethylpterin as a model compound. Influx proceeds by a mechanism that exhibits a Km of 66.7 microM and a Vmax of 0.077 nmol/min per mg cellular protein. The process is somewhat sensitive to metabolic inhibitors, particularly uncouplers of oxidative phosphorylation, and is significantly affected by the presence of other pteridines in the extracellular medium. The results suggest that pterins with either no 6-substituent (pterin) or those with methyl, hydroxyl, or formyl groups in this position, which exhibit Ki values between 25 and 77 microM, may share the same pathway for uptake. 6-Carboxypterin exhibits low affinity for the system (Ki greater than 500 microM), as do 7-substituted and 6,7-di-substituted derivatives and compounds with larger groups at the 6-position, such as neopterin and biopterin (Ki = 250-300 microM). Efflux of [3H]6-hydroxymethylpterin occurs rapidly and can proceed by at least two routes. The first, comprising approximately 50% of total efflux, is inhibited by extracellular pterins and exhibits similar properties to the uptake system in both its pattern of sensitivity to metabolic inhibitors and its specificity for pteridine structure. The route by which the remaining efflux occurs is relatively insensitive to metabolic inhibition. Adenine significantly inhibits 6-hydroxymethylpterin influx and efflux (Ki = 10.6 microM for uptake) but does not appear to share the same transport system. Similarly, methotrexate and folic acid exhibit little affinity for the unconjugated pteridine transport routes.

[Immunologic variants of acute lymphoblastic leukemia in adults and its correlation with cytochemical and various clinical parameters]

The authors provide data pertaining to the immunological phenotyping in the panel of monoclonal antibodies to various differentiating antigens of the leukemic cells in 27 patients with acute lymphoblastic leukemia (ALL). Based on the composition of the differentiating antigens of the leukemic cells the following immunological variants of the disease were identified: pre-B, pre-T and T-ALL--the thymic and mature (activated) ones. The phenotype was compared with the cytochemical parameters of the lymphoblasts of the identified immunological variants of ALL and with some clinical and hematological manifestations of the disease. The comparison of the data obtained during blast cell immunophenotyping with the cytochemical parameters and some clinicohematological findings suggests the development of a more fundamental classification of ALL in order to perfect the treatment of the patients suffering from ALL.

Abnormalities in the erythrocyte membrane in acute lymphoid leukaemia

Erythrocytes from patients suffering from acute lymphoid leukaemia (ALL) show decreased proportions of spectrin tetrameters and altered spatial distribution of band 4.1 and ankyrins. These abnormalities of the cytoskeleton are probably responsible for altered membrane fluidity and transbilayer distribution of phosphatidylethanolamine in ALL. ALL is associated with severe anaemia and usually, but not always, with overproduction of lymphocytes. To our knowledge, this is the first report of abnormalities in the erythrocyte membrane in ALL which may, in part, be responsible for the observed anaemia.

Elevated production of interleukin-2 by lymphocytes from children with acute leukemia

Abnormalities of the production of interleukin-2 (IL-2) may play an important role in the immunologic dysfunction observed in pediatric leukemia patients. For an evaluation of the ability of lymphocytes from leukemic children to produce this cytokine, the production of IL-2 by mitogen-stimulated peripheral blood mononuclear cells was determined in children with acute leukemia at the time of diagnosis, during clinical remission, and at the time of relapse. Of 16 patients, 11 (69%) with either acute lymphoblastic leukemia or acute nonlymphoblastic leukemia at the time of diagnosis had IL-2 production levels above the highest level observed in control subjects, and all but one had values above the control mean. Three of five treated patients had elevated IL-2 production at the time of bone marrow relapse. In addition, of 37 patients examined during clinical remission (both during chemotherapy and after the completion of maintenance chemotherapy), five had IL-2 production values above the control range and four of these five patients subsequently had relapses, compared with only one relapse in the remaining 32 patients with normal or below-normal levels of IL-2 production. These results demonstrate an increased ability to produce IL-2 by many patients with acute leukemia, both at the time of diagnosis and at relapse. Elevated IL-2 production may represent an immunologic response to leukemic cells and in some patients may provide a marker for persistent leukemia.

Immunoelectron microscopy studies on the modulation of common acute lymphoblastic leukemia antigen (CALLA) on NALM-6 cells: delineation of intracellular transport

Even though much is known about the presence of the common acute lymphoblastic leukemia antigen (CALLA) with respect to its distribution in hematopoietic and non-hematopoietic tissues, its functional role in lymphoid cells is as yet unknown. Given the fact that CALLA is completely modulated on the surface of lymphoid cells, we have employed pre-embedding immunogold techniques at electron-microscopical level and demonstrated that J5 monoclonal antibody (MoAb)-mediated modulation of CALLA expression on the lymphoblastic cell line NALM-6 is a specific, rapid process, closely resembling receptor-mediated endocytosis. Furthermore, it was found that CALLA was internalized through plasmalemmal pits and cytoplasmic vesicles and processed intracellularly in multivesicular bodies and secondary lysosomes. In contrast, HLA-DR antigen remained at the cell surface upon contact with specific MoAb. These data suggest that CALLA might be a receptor for a hitherto unknown signal molecule.

Leukemic B-cell precursors express functional receptors for human interleukin-3

The purpose of this study was to analyze the expression of functional interleukin-3 (IL-3) receptors on leukemic B-cell precursors (BCPs) from 12 BCP acute lymphoblastic leukemia (ALL) patients and five BCP ALL cell lines. The specific binding of biosynthetically labeled 35S-recombinant (r) IL-3 to freshly obtained leukemic marrow blasts was initially investigated. In five of 12 BCP ALL cases, the binding of 35S-rIL-3 was markedly blocked by excess cold rIL-3, and the percentage of inhibitable binding ranged from 53% to 78% (mean +/- SE = 65% +/- 4%). In these cases, the cell-bound radioactivity ranged from 146 cpm/10(7) cells to 1,433 cpm/10(7) cells (mean +/- SE = 627 +/- 250 cpm/10(7) cells), indicating that 1 to 14 femtomole (mean +/- SE = 6 +/- 2 fms) of [35S]rIL-3/10(7) cells were specifically bound (= 60 to 840 molecules per cell). rIL-3 stimulated the proliferative activity of leukemic BCPs in a dose-dependent fashion without inducing differentiation, and the half-maximal stimulatory activity was observed at a concentration of 17 to 34 pmol/L. Fluorescence-activated cell sorter (FACS)-isolated virtually pure populations of CD10+CD19+ leukemic BCPs from two BCP ALL patients, as well as from two of five BCP ALL cell lines, showed a marked proliferative response to highly purified rIL-3, providing formal evidence that the observed IL-3 responses were not mediated by accessory cells. There was a high correlation between [35S]rIL-3 binding and proliferative response in colony assays, indicating that functional IL-3 receptors were detected in ligand binding assays. Scatchard plot analysis of the specific equilibrium binding data for IL-3-responsive leukemic BCPs from one BCP ALL patient and two BCP ALL cell lines yielded a straight linear regression line, indicating the existence of a single class of 60 to 210 high-affinity IL-3 binding sites/cell. The calculated apparent affinity constant (Ka) values ranged from 3.6 x 10(9) to 5.9 x 10(9) mol/L-1. Hence, the concentration of IL-3 required to produce 50% maximal receptor occupancy (Kd) was in the range of 168 to 280 pmol/L. These concentrations are approximately tenfold higher than those required to induce 50% maximal proliferative response from leukemic BCPs in colony assays, indicating that low receptor occupancy is sufficient for growth stimulation of leukemic BCPs by rIL-3. In comparison, less than 10 to 20 IL-3 molecules/cell were bound to IL-3 unresponsive leukemic BCPs even when the concentration of free-[35S]rIL-3 was as high as 2 nmol/L.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of retinoic acid on the phosphorylation of endogenous proteins in HL-60 cells

HL-60 cells were incubated with [32P]-Pi in order to label endogenous phosphoproteins in situ. These were then resolved via two-dimensional electrophoresis and autoradiograms were made from the gels. A comparison of autoradiograms made from retinoic-acid-differentiated cells with those made from control cells revealed a small number of phosphoproteins whose labeling was enhanced in differentiated cells. Incubating HL-60 cells with [35S]-methionine revealed that RA induced the synthesis of one of these proteins, (53 kDa, pl 4.8) although not to a degree sufficient to account for the increased phosphate labeling observed in differentiated cells. Difluoromethylornithine (DFMO), which arrests HL-60 cell proliferation without inducing differentiation, had no effect on endogenous protein phosphorylation. Treatment of DFMO-arrested cells with retinoic acid, however, increased the phosphorylation of the proteins and resulted in differentiation of the cells. Densitometric analysis of autoradiograms made from two-dimensional gels revealed that the phosphorylation of the 53-kDa, pl 4.8 protein was significantly elevated in cells exposed to RA for as little as 12 hours, i.e., before the cells were committed to differentiate and before a significant increase in the number of phenotypically mature cells was observed. It therefore appears that this protein may be an intermediate in the retinoic-acid-induced differentiation process.