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Results for “LEUKEMIA, LYMPHOCYTIC”

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At least 19 recordsLinked to original sources

PubMed1976

Comparison of normal and chronic lymphocytic leukemia lymphocyte surface Ig determinants using peroxidase-labeled antibodies. II. quantification of light chain determinants in atypical lymphocytic leukemia.

Five cases of atypical lymphocytic leukemia were investigated with regard to their membrane-associated light chains. Detection and quantitation of antigenic determinants were performed by means of peroxidase-labeled antibodies according to Avrameas et al. The cases studied had clinical and cytologic features in common: an active clinical course, marked splenomegaly, severe anemia and thrombocytopenia, little or no lymph node enlargement, and very high white blood counts with small mature lymphocytes and poorly differentiated lymphoid cells. Blood lymphocytes of all patients carried a single type of light chain, and 90%-100% of the cells were stained. The average number of antigenic sites per cell was 72,500 (range 40,000-97,500). These results differed from those previously found in typical CLL (mean value 9000) and approached the values of normal peripheral blood lymphocytes (90,000). The criteria investigated in this study could be of value for the diagnosis and prognosis of some atypical forms of lymphocytic leukemia.

Aged↗

PubMed1989

Chlorambucil pharmacokinetics and DNA binding in chronic lymphocytic leukemia lymphocytes.

Chlorambucil (CLB) uptake by chronic lymphocytic leukemia lymphocytes was studied using a radiometric and a newly developed high-performance liquid chromatography assay. CLB labeled with 14C in either the chloroethyl group or phenyl ring was used with identical results. Drug accumulation by the cells was found to peak at 30 s, was independent of temperature, and was proportional to medium CLB concentration over a wide range. Efflux from cells loaded with CLB and resuspended in drug-free medium was nearly complete at 30 s. The metabolic inhibitors 2-deoxyglucose and NaN3, the nitrogen mustard transport inhibitor hemicholinium-3, and another alkylating agent, melphalan, had no effect on drug uptake. We conclude that CLB enters and exits chronic lymphocytic leukemia lymphocytes by simple diffusion. Cells from 17 patients with all stages of chronic lymphocytic leukemia were studied including three with CLB-resistant disease, and no heterogeneity was found in the peak cell-associated CLB content or in metabolite pattern on high-performance liquid chromatography. These findings make it unlikely that transport or cellular drug metabolism are factors in drug resistance. Drug-DNA binding was found to be temperature-sensitive and increased with time of incubation. Gel filtration of DNA before and after enzymatic digestion indicated the presence of drug-DNA adducts. High-performance liquid chromatography analysis of digested DNA and DNA treated by neutral thermal hydrolysis suggested the presence of multiple adducts. Most of the radioactivity was found as purine adducts. Studies with CLB labeled at two different sites revealed the presence of the phenyl group and ethyl chains in the adducts. A survey of patients showed increased drug-DNA binding in cells from patients with clinical CLB resistance.

Chlorambucil↗

PubMed2002

UCN-01 (7-hydroxystaurosporine) inhibits DNA repair and increases cytotoxicity in normal lymphocytes and chronic lymphocytic leukemia lymphocytes.

Elevated DNA repair processes represent resistance mechanisms to the treatment of malignancies with alkylating agents. Recently, the cell cycle checkpoint abrogator, UCN-01, was reported to inhibit nucleotide excision repair in cell-free systems. We hypothesized that if UCN-01 was combined with DNA-damaging agents, UCN-01 might inhibit the damage repair processes, thereby enhancing cytotoxicity in quiescent cells. Here, we investigated the effect of UCN-01 on DNA repair and viability of quiescent normal lymphocytes and chronic lymphocytic leukemia lymphocytes treated with UV or the cyclophosphamide prodrug 4-hydroperoxycyclophosphamide (4-HC). DNA damage repair kinetics were determined as DNA single strand breaks by the alkaline single cell gel electrophoresis (comet) assay and by [3H]thymidine incorporation. Pretreatment with UCN-01 inhibited DNA repair initiated by UV or 4-HC in normal lymphocytes as well as chronic lymphocytic leukemia lymphocytes in a concentration-dependent manner at clinically relevant levels (50-300 nM). This inhibition was demonstrated by the decreases in incision capability, DNA resynthesis, and in rejoining, suggesting that UCN-01 inhibits the multiple sites of the repair processes. The higher UCN-01 concentration (300 nM) maximized the inhibitory effects and enhanced the UV- or 4-HC-induced cytotoxicity, as determined by annexin V binding or Hoechst 33342 staining. This enhancement was not obtained by the lower concentrations that incompletely inhibited the repair, suggesting the close association between the inhibition of the repair and the enhancement of the cytotoxicity. Our findings suggest that UCN-01 may be a good candidate for combination strategies of cancer treatment.

Alkaloids↗

PubMed1983

Purification and characterization of actin from normal and chronic lymphocytic leukemia lymphocytes.

Previous studies from this laboratory have shown actin to be a major protein of human lymphocytes (Stark, R., Liebes, L. F., Nevrla, D., and Silber, R. Biochem. Med., 27: 200-206, 1982). We now report the purification to homogeneity and characterization of actin from blood lymphocytes of normal subjects and patients with chronic lymphocytic leukemia. The recovery of the purified protein was about 20%. The properties of the lymphocyte actins were compared to each other and to those of rabbit skeletal muscle actin. Lymphocyte actin consisted of beta and gamma forms in a 2:1 ratio. The Mr 42,000 was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Normal and leukemic lymphocyte actin had similar polymerization properties as assessed by viscosity measurements at 25 degrees and 4 degrees, and the ultrastructural appearance of the filaments was the same. Similar patterns were observed between normal and chronic lymphocytic leukemia actin tryptic digests analyzed by high-performance liquid chromatography. The Vmax of the actin-activated myosin Mg2+ ATPase activity was compared using rabbit skeletal muscle heavy meromyosin and subfragment 1 preparations. The values obtained with rabbit skeletal muscle and normal lymphocyte actin were identical. The Vmax observed with chronic lymphocytic leukemia lymphocyte actin was 70% of that obtained with normal lymphocyte actin. The amount of actin needed to produce half-maximal activation (Kapparent) of heavy meromyosin and subfragment 1 were, respectively, 26 and 25 microM for normal lymphocytes and 18 and 24 microM for chronic lymphocytic leukemia lymphocytes. The anomalous ATP activation by actin did not reflect differences in B-:T-cell subpopulations between chronic lymphocytic leukemia and normal lymphocytes. The possible significance of the observed differences between the myosin Mg2+ ATPase activation by chronic lymphocytic leukemia and normal lymphocyte actin is discussed.

Actins↗

PubMed1977

Human lymphocyte complement receptors. Quantitative requirements for C3 of normal and chronic lymphocyte leukemia lymphocytes.

Erythrocytes coated with varying amounts of human complement were used to detect lymphocytes with complement receptors from normal subjects and patients with chronic lymphocytic leukemia. The relationship between the percentage of lymphocytes rosetting and the quantity of C3 present on complement-coated erythrocytes were studied. Small quantities of C3 (less than 5 fg/erythrocyte) caused maximal rosetting of normal lymphocytes. Maximal rosetting with chronic lymphocytic leukemia lymphocytes was not reached until much greater amounts of C3 were used to coat the erythrocytes. This difference in sensitivity to erythrocyte-bound complement was not due to an increased fraction of complement receptor-bearing cells in the leukemic patients. This loss of sensitivity of the chronic lymphocytic leukemia lymphocyte for complement may play a role in the immune deficiency present in this disease.

Cell Membrane↗

PubMed1977

Chromatin phospholipids in normal and chronic lymphocytic leukemia lymphocytes.

Certain phospholipids are associated with the nonhistone chromosomal proteins extracted from normal B- and chronic lymphocytic leukemia lymphocytes. The ratio of phospholipids to nonhistone chromosomal proteins was constant with the different methods used for isolating nuclei and extracting the chromatin, although the various methods allowed a different recovery of total lipids from chromatin. Three phospholipids were extractable from the nonhistone protein fraction, but their respective ratios varied in chronic lymphocytic leukemia compared to normal B-lymphocytes. The most significant variation concerns the reduction of sphingomyelin content in leukemic lymphocytes, since this prospholipid in vitro affects both DNA stability and transcription.

B-Lymphocytes↗

PubMed1975

Chromatin proteins from human lymphocytes: a gel electrophoretic comparison between normal, mitogen-stimulated, cell-line, and chronic lymphocytic leukemia lymphocytes.

Cell-line lymphocytes contained considerably more nonhistone chromatin protein than normal lymphocytes. The overall electrophoretic pattern of the nonhistone chromatin proteins from nonreplicating cell types with predominantly condensed chromatin (normal lymphocytes and chronic lymphocytic leukemia lymphocytes) was similar, as it was between replicating cell types with predominantly decondensed chromatin (mitogen-stimulated normal lymphocytes and cell-line lymphocytes), although all four cell types differed qualitatively. A "heavy" chromatin fraction from cell-line lymphocytes could be distinguished from a "light" fraction and had a pattern similar to that from cells of the condensed chromatin type. Normal lymphocytes contained two acid-soluble chromatin polypeptieds not found in cell-line lymphocytes.

Cell Fractionation↗

PubMed1994

Increased glutathione in chronic lymphocytic leukemia lymphocytes.

Following reports on a variety of interactions between glutathione (GSH) concentration and clinical parameters in solid tumors, a study was undertaken in order to determine the GSH intracellular content of chronic lymphocytic leukemia (CLL) lymphocytes. The results from a group of 16 patients consecutively studied indicate tht B-CLL cells have twice as much GSH as lymphocytes from normal subjects, suggesting that this measurement may be helpful in the understanding of the metabolic mechanism of the disease and the rationale of therapy.

Glutathione↗

PubMed2001

DNA repair initiated in chronic lymphocytic leukemia lymphocytes by 4-hydroperoxycyclophosphamide is inhibited by fludarabine and clofarabine.

PURPOSE: Chronic lymphocytic leukemia (CLL) lymphocytes respond to DNA alkylation by excision repair, with the extent of repair increasing as the cells acquire resistance to alkylating agents. Because incorporation of nucleotide analogues into the repair patches elicits death signals in quiescent cells, the increased capacity for excision repair in alkylator-resistant cells could facilitate incorporation of nucleotide analogues. We hypothesized that the mechanism-based interaction of nucleoside analogues with alkylating agents could elicit greater than additive killing of CLL cells. EXPERIMENTAL DESIGN: Lymphocytes from 50 patients with CLL that were not refractory to alkylators were treated in vitro with 4-hydroperoxycyclophosphamide (4-HC) with or without prior incubation with fludarabine nucleoside (F-ara-A) or with clofarabine (Cl-F-ara-A). DNA damage repair kinetics were determined by the single-cell gel electrophoresis (comet) assay. Cytotoxicity was assessed by staining with annexin V. RESULTS: CLL lymphocytes promptly initiated and completed excision repair in response to 4-HC. A 2-h preincubation with 10 microM F-ara-A or 10 microM Cl-F-ara-A inhibited the repair initiated by 4-HC, with inhibition peaking at the intracellular concentrations of 50 microM F-ara-ATP or 5 microM Cl-F-ara-ATP. Combining 4-HC with either F-ara-A or Cl-F-ara-A produced more than additive apoptotic cell death than the sum of each alone. The increase in cytotoxicity was proportional to the initial magnitude of the DNA incision and to the extent of repair inhibition by the nucleoside analogues, suggesting close correlation between the repair inhibition and induction of cell death. CONCLUSIONS: DNA repair, which is active in CLL lymphocytes, may be a biological target for facilitating the incorporation of nucleoside analogues and increasing their cytotoxicity. Thus, the increased repair capacity associated with resistant disease may be manipulated to therapeutic advantage.

Adenine Nucleotides↗

PubMed2006

Fludarabine increases oxaliplatin cytotoxicity in normal and chronic lymphocytic leukemia lymphocytes by suppressing interstrand DNA crosslink removal.

Oxaliplatin and fludarabine have different but potentially complementary mechanisms of action. Previous studies have shown that DNA repair is a major target for fludarabine. We postulate that potentiation of oxaliplatin toxicity by fludarabine may be due to the inhibition by fludarabine of the activity of the DNA excision repair pathways activated by oxaliplatin adducts. To test this, we investigated the cytotoxic interactions between the 2 drugs in normal and chronic lymphocytic leukemia (CLL) lymphocytes. In each population, the combination resulted in greater than additive killing. Analysis of oxaliplatin damage revealed that fludarabine enhanced accumulation of interstrand crosslinks (ICLs) in specific regions of the genome in both populations, but to a lesser extent in normal lymphocytes. The action of fludarabine on the removal of oxaliplatin ICLs was explored to investigate the mechanism by which oxaliplatin toxicity was increased by fludarabine. Lymphocytes from patients with CLL have a greater capacity for ICL unhooking compared with normal lymphocytes. In the presence of fludarabine the extent of repair was significantly reduced in both populations, more so in CLL. Our findings support a role of fludarabine-mediated DNA repair inhibition as a mechanism critical for the cytotoxic synergy of the 2 drugs.

Adult↗

PubMed1998

DNA-Dependent protein kinase activity correlates with clinical and in vitro sensitivity of chronic lymphocytic leukemia lymphocytes to nitrogen mustards.

The objective of this study is to investigate the role of DNA-dependent protein kinase (DNA-PK) in the chronic lymphocytic leukemia (CLL) lymphocyte response to nitrogen mustard therapy. DNA-PK is a nuclear serine/threonine kinase that functions in DNA double-strand break repair and in the joining process in recombination mechanisms. In a series of 34 patients with B-CLL, either untreated (n = 16) or resistant to chlorambucil (n = 18), the kinase activity of the complex, as determined by its capacity to phosphorylate a peptide substrate in vitro, is increased in the resistant samples as compared with the untreated ones (24.4 +/- 2.6 arbitrary units [a.u.] [range, 12.7 to 55.8 a.u.] versus 8.1 +/- 2.8 a.u. [range, 0.9 to 44.5 a.u.], respectively (P < .0001]), independent of other clinical and biological factors. Linear regression analysis shows an excellent correlation between the level of DNA-PK activity and the inherent in vitro sensitivity of CLL lymphocytes to chlorambucil (r = .875, P =.0001). The regulation of DNA-PK activity was associated with increased DNA-binding activity of its regulatory subunit, the Ku heterodimer, in resistant samples. These results suggest that this activity is a determinant in the cellular response to chlorambucil and participates in the development of nitrogen mustard-resistant disease. The increase in DNA-PK activity might contribute to the enhanced cross-link repair that we previously postulated to be a primary mechanism of resistance to nitrogen mustards in CLL.

Aged↗

PubMed1981

Lactic dehydrogenase in normal and leukemia lymphocyte subpopulations: evidence for the presence of abnormal T cells and B cells in chronic lymphocytic leukemia.

Lactic dehydrogenase (LDH) was quantitated and the isozyme pattern studied in lymphocyte subpopulations from normal people and patients with chronic lymphocytic leukemia (CLL). Normal T lymphocytes differed from normal B lymphocytes in having greater total LDH activity (597.2 versus 252.1). Total LDH activity in CLL T cells (347.1) was lower than normal T cells., but not significantly different than normal B cells. Total LDH activity in CLL B cells (124.6) was lower then normal B cells and normal T cells. The isozyme pattern of normal T lymphocytes showed a higher activity in the LDH-1 band (26.7% versus 5.4%) but showed a lower activity in LDH-5 band (4.3% versus 16.3%) compared to normal B cells. Chronic lymphocytic leukemia T cells could be distinguished from CLL B cells by a high LDH-5 band (22.3% versus 7.6%) and from normal T cells by a high LDH-5 band (22.3% versus 4.3%) and a low LDH-1 band (7.3% versus 26.7%). CLL B cells could be distinguished from normal B cells by a low LDH-5 band (7.6% versus 16.3%). Thus, the LDH isozyme pattern distinguishes normal T lymphocytes from normal B lymphocytes, and normal T and B lymphocytes from CLL T and B lymphocytes.

Adult↗

PubMed1976

Cyclic adenosine 3':5'-monophosphate phosphodiesterase activity in normal and chronic lymphocytic leukemia lymphocytes.

The specific activity of cyclic adenosine 3':5'-monophosphate phosphodiesterase was measured in lymphocytes isolated from the blood of normal subjects, from patients with chronic lymphocytic leukemia, and from tonsil tissue. The mean specific activity of cyclic adenosine 3':5'-monophosphate phosphodiesterase in the lymphocytes from patients with untreated chronic lymphocytic leukemia was lower than that in lymphocytes from the blood of normal subjects or from tonsils. Cyclic adenosine 3':5'-monophosphate phosphodiesterase levels did not correlate with differences in B- and T-cell lymphocyte subpopulations or with peripheral blood lymphocyte counts.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1984

Anomalous function of vimentin in chronic lymphocytic leukemia lymphocytes.

Chronic lymphocytic leukemia (CLL) lymphocytes manifest anomalous motility and cap formation. Since these processes involve cytoskeletal proteins, vimentin from intermediate filaments of normal and CLL lymphocytes was investigated using hetero- and monoclonal antisera. The antisera reacted predominantly with a 60-kD polypeptide, following sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of total lymphocyte proteins. When lymphocytes were stained by indirect immunofluorescence, normal lymphocytes demonstrated well defined cytoplasmic fibrils that capped spontaneously after contact with a glass surface and incubation at 37 degrees C. This capping was dependent on energy and intact microfilaments. Lymphocytes from patients with CLL showed several patterns. In one group, the initial staining was weak, and few capped cells were present after incubation. Lymphocytes from other patients had either normal or aberrantly organized fibrils in which capping was diminished. In another group, a fibrillar pattern with normal or increased capping was seen. In total, 47% +/- 5.1% (mean +/- SE) of normal lymphocytes capped after a 1-hr incubation at 37 degrees C (n = 12) compared to 21% +/- 5.1% for CLL lymphocytes (n = 20, p less than 0.002). Purified subpopulations of normal B and T cells did not differ from unfractionated normal lymphocyte populations. These results demonstrate an anomalous vimentin capping response in CLL lymphocytes. They also show that the arrangement of vimentin in these cells differs from that of normal lymphocytes.

Antibodies, Monoclonal↗

PubMed1988

Unmasking of cryptic natural killer (NK) cell recognition sites on chronic lymphocytic leukemia lymphocytes.

The sensitivity of chronic lymphocytic leukemia (CLL) lymphocytes to attack by natural killer (NK) cells has remained questionable. To clarify this issue, freshly isolated lymphocytes of 37 patients with B-CLL, five with WDLL and two with HCL, were tested with a standard cytotoxicity assay with NK cells from normal donors. All these targets were resistant to cytolysis by the effectors. Freeze-fracture analysis of CLL cell plasma membranes revealed that they have a larger number of intramembranous particles (IMP) associated with the external leaflet (E-face) than have normal lymphocytes. Unlike other neoplastic cells, exposure of CLL lymphocytes to phorbol esters or treatment with neuraminidase did not render them vulnerable to attack by NK cells, nor did 5 days of culture have an effect. Incubation of CLL lymphocytes with anti-Ig-mu (24-72 hr) or with 0.1% pepsin (15 min) resulted in 15% and 27% cytolysis, respectively. B-lymphocytes from the blood of healthy donors were not killed when treated similarly: These data establish that freshly isolated B-CLL lymphocytes are resistant to NK cytolysis but that in contrast to normal B-cells, they possess cryptic NK-recognition structures, which may be uncovered by surface modulation.

Antibodies, Anti-Idiotypic↗

PubMed1999

Pre-clinical evaluation of SN-38 and novel camptothecin analogs against human chronic B-cell lymphocytic leukemia lymphocytes.

The topoisomerase I inhibitor camptothecin and its analogs have potent activity against a wide range of solid tumors and several hematologic malignancies. Previous studies with these compounds using the MTT metabolic inhibition assay have shown significant cytotoxicity against lymphocytes from patients with chronic B-cell lymphocytic leukemia (B-CLL). Yet the water soluble analogue, topotecan, which was inhibitory at > 1 microM in vitro, had no clinical activity in vivo. In the present study, we evaluated the in vitro cytotoxicities of SN-38, the active form of irinotecan, and two newer water soluble camptothecin derivatives 10,11-methylenedioxy-20(S)-camptothecin glycinate (MDCG) and 7-chloromethyl-10,11-methylenedioxy-20(S)-camptothecin glycinate (CMMDCG). These two glycinate esters are prodrugs for 10,11-methylenedioxy-20(S)-camptothecin (MDC) and 7-chloromethyl-10,11-methylenedioxy-20(S)-camptothecin (CMMDC), respectively. Effects on cellular metabolism, induction of apoptosis, and overall cell survival were used to evaluate chemosensitivity. We report that the relative cytotoxic potency for these compounds is MDC > or = CMMDC > or = SN-38 >> TPT > CPT-11, where MDC, CMMDC, and SN-38 were over an order of magnitude more cytotoxic than TPT and CPT-11. We also investigated potential mechanisms underlying the unexpected cytotoxicity of these camptothecin derivatives in B-CLL cells that are known to be arrested in G0/G1 of the cell cycle, and found that this class of compounds inhibited [3H]uridine incorporation. We therefore postulate that the inhibition of RNA rather than DNA synthesis may be responsible for the observed cytotoxicity in non-cycling B-CLL cells.

Antineoplastic Agents, Phytogenic↗

PubMed1989

Na+/H+ exchange activation mediates the lipopolysaccharide-induced proliferation of human B lymphocytes and is impaired in malignant B-chronic lymphocytic leukemia lymphocytes.

In various mammalian cell types the stimulation of the plasma membrane amiloride-sensitive Na+/H+ exchange and the resulting increase of intracellular pH (pHi) play a key role in the initiation of cell proliferation. In the present work we have investigated whether Na+/H+ exchange is involved in normal human B cell proliferation and whether it is also operating in malignant B-chronic lymphocytic leukemia (B-CLL) lymphocytes. Our results show that: 1) normal human B cells contain an operating Na+/H+ exchanger, as inferred by their ability to recover pHi after acid-loading in a HCO3- -free medium and by evidences that LPS and phorbol ester PMA elicit a pHi rise inhibitable by either 5-(N-ethyl-N-isopropyl)amiloride (EIPA) or a Na+-free medium; 2) LPS-induced proliferation of normal human B cells is strongly inhibited when the amiloride analog EIPA (5 microM) is present in the culture medium (after 72 h the proportion of B cells incorporation bromodeoxyuridine falls from 13.9 +/- 3.9% to 2.8 +/- 1.1%); 3) EIPA does not affect BdR incorporation when B cells proliferation is induced by the co-mitogenic activity of IL-4 and low m.w. B cell growth factor (BCGF); 4) B-CLL cells, which proliferate in response to IL-4/BCGF but not to LPS, fail to increase pHi above their pHi resting levels when challenged with LPS or PMA and pHi recovery after acid-loading is highly impaired. These results lead to conclude that Na+/H+ exchange operation is necessary for LPS-(but not for IL-4/BCGF)-induced proliferation of human normal B lymphocytes and that Na+/H+ exchange activation is impaired in malignant B-CLL lymphocytes.

Aged↗

PubMed1994

Proliferative response of B chronic lymphocytic leukemia lymphocytes stimulated with IL2 and soluble CD23.

The in vitro proliferative response of purified B-chronic lymphocytic leukemia (B-CLL) lymphocytes cultured in the presence of soluble CD23 (sCD23) with or without IL2 was compared to the responses induced by phorbol 12-myristate 13-acetate (PMA), Staphylococcus aureus strain Cowan I (SAC), IL1, IL2, IL4, IL6 and the combination of IL2 and interferon (IFN) alpha or IFN gamma. As expected, B-CLL lymphocytes proliferated with PMA, SAC and IL2 with a clear enhancement of the IL2-induced response by IFN alpha or IFN gamma. They failed to proliferate in response to sCD23, IL1, IL4 or IL6 alone nor to the combinations of sCD23 and any of the 3 latter cytokines. However, sCD23 significantly increased the proliferation of B-CLL cells induced by IL2, suggesting a protective effect of sCD23 on apoptosis. Serum levels of sCD23 and CD23 membrane expression were high in every patient which is compatible with the hypothesis of an autocrine or paracrine activation loop. Detectable CD23 expression was lost in all cultures except for that stimulated by PMA. Only supernatants of PMA-stimulated cultures contained high sCD23 levels.

Adult↗