Inhibition of Telomerase with hTERT Antisense Increases Susceptibility of Leukemic Cells to CDDP-induced Apoptosis

Objective: To investigated the e?ect of inhibition of telomerase with hTERT antisense on leukemic cells (HL-60 and K562) to CDDP-induced apoptosis. Methods: Antisense phosphorothioate oligodeoxynucleotide (AS PS-ODN) was synthesized and puri?ed. Telomerase activity was detected by Telomerase PCR ELASA kit and cell apoptosis was observed by morphological method and determined by ?owcytometry. Results: AS PS-ODN could signi?cantly inhibit telomerase activity by down regulat- ing the hTERT expression, and increase the susceptibility of leukemic cells to CDDP-induced apoptosis. Conclusion: Inhibition of telomerase with hTERT antisense can increases the susceptibility of leukemic cells to CDDP-induced apoptosis.

Inhibition of Leukemic Cell Telomerase Activity by Antisense Phosphorothioate Oligodeoxynucleotides

Objective To evaluate the effect of human telomerase reverse transcriptase (hTERT) gene antisense oligodeoxynucleotide (ASODN) ontelomerase activity in K562 cells.Methods Telomerase activity was determined by polymerase chain reaction enzyme-linked immunoassay (PCR-ELISA) in K562 cellstreated with ASODN and hTERT mRNA expression was detected by reverse transcriptase polymerase chain reaction (RT-PCR).Results The hTERT mRNA level was decreased, and teloraerase activity was significantly inhibited when the K562 cells were treated withASODN for 48 h.Conclusion It is suggested that hTERT ASODN might specifically inhibit telomerase activity of K562 cells at translation level, and it isfurther proved that hTERT gene has significant correlation with telomerase activity.

ELECTRON MICROSCOPIC OBSERVATION OF DIFFERENTIATION OF LEUKEMIC CELL CLONE AFTER CFU-MIX CULTURE

By scanning and transmission electron microscopy, leukemlc celb were obwrved after CFU-Mix culture. Even though granulocytlc growth factor, erythropoietin and lymphocytlc growth factor were added at vitor, acute leukemlc celb still showed defects In differentiation and maturation. These were characterized by abnormal colony which consisted of smooth cells, bizarre shape, nuclear-cytoplasmic asynchrony In development, and appearance of nuclear bleb. However, chronic myelogenous leukemlc celb were more nature than the acute ones, manifesting in normal colony with finger- like projections and ruffled membrane. Macrophages and eosinophils could be observed. It b suggested that there b a difference In differentiation between acute and chronic leukemia cells.

THE PRELIMINARY APPLICATION OF IN SITU HYBRIDI-ZATION IN DETECTING PROTO-ONCOGENES EXPRESSION IN HUMAN LEUKEMIC CELLS

An in situ hybridization technique with 35S labelled proto-oncogene probes (c-myc & c-fes) was used to detect their expression in bone marrow cells of 22 cases of leukemia of various types and immature granulocytes and erythroblasts of 16 nomal myelograms as controls. Both c-myc and c-fes were detectable in leukemic cells as well as in immature granulocytes and erythroblasts of normal bone marrow, but the expression extent varied in different cases. The levels of c-myc expression in leukemic cells were higher than those in controls (P<0.001). There was no difference of c-fes expression in two groups of bone marrow cells (P>0.05). This technique provides us a new method in studying variations of proto-oncogene expression in leukemic cells.

Expressions of IL-10 on leukemic cells in acute leukemic patients and its significance

Objective: To explore the expressions of IL-10 on leukemic cells in acute leukemia patients and its significance. Methods: The expressions of IL-10 on leukemic cells in thirty patients was measured by indirect immunofluorescence technique. Results: Observed yellow-green bright fluorescence on leukemic cells membrane, the positive rate of cells was 10-80%, there were 18 patients expressing IL-10 (18/30, 60%) positively, among them 11 with ANLL (11/19, 58%) and 7 with ALL (7/11, 64%) respectively while that of peripheral mononucleate cells in control group was 13%. Compared with that in the control group, there was a significant increase of positive rate in ANLL and ALL but with no significant difference between ANLL and ALL. Conclusion: IL-10 secreted by leukemic cells, contributed to the immunosuppressive state at the tumor site. This is probably one of the important mechanisms of acute leukemic escape.

Expression and Fuactional Role of HERG1, K^+ Channels in Leukemic Cells and Leukemic Stem Cells

In order to investigate the expression and functional role of HERG1 K+ channels in leukemic cells and leukemic stem cells (LSCs), RT-PCR was used to detect the HERG1 K+ channels expression in leukemic cells and LSCs. The functional role of HERG1 K+ channels in leukemic cell proliferation was measured by MTT assay, and cell cycle and apoptosis were analyzed by flow cy- tometry. The results showed that herg mRNA was expressed in CD34+/CD38-, CD123+ LSCs but not in circulating CD34+ cells. Herg mRNA was also up-regulated in leukemia cell lines K562 and HL60 as well as almost all the primary leukemic cells while not in normal peripheral blood mononuclear cells (PBMNCs) and the expression of herg mRNA was not associated with the clinical and cytoge- netic features of leukemia. In addition, leukemic cell proliferation was dramatically inhibited by HERG K+ channel special inhibitor E-4031. Moreover, E-4031 suppressed the cell growth by induc- ing a specific block at the G1/S transition phase of the cell cycle but had no effect on apoptosis in leukemic cells. The results suggested that HERG1 K+ channels could regulate leukemic cells prolif- eration and were necessary for leukemic cells to proceed with the cell cycle. HERG1 K+ channels may also have oncogenic potential and may be a biomarker for diagnosis of leukemia and a novel potential pharmacological target for leukemia therapy.

Induction of apoptosis by homoharringtonine in G1 phase human chronic myeloid leukemic cells

Background Homoharringtonine (HHT) is a cephalotaxine ester derived from an evergreen tree found wildely throughout southern China, which has antileukemic activities against a variety of acute myeloid leukemic cells. For the sake of illustrating the mechanisms of HHT in the treatment of leukemia, we assessed the effect of HHT on the apoptosis of human chronic myeloid leukemic cell line K562.Methods The apoptosis of K562 cells induced by HHT was analyzed by transmission electron microscopy, agarose gel electrophoresis of DNA, flow cytometry and terminal deoxyribonucleotidyl transferase-mediated dUTP-biotin nick labeling.Results Characteristic apoptosis-related features emerged in K562 cells after exposed to HHT at a concentration 0.05-100 μg/ml. Transmission electron microscopy of HHT treated K562 cells displayed chromatin condensation and aggregation under the nuclear membrane, nuclear fragmentation and apoptosis body formation. Typical DNA ladder in agarose gel electrophoresis was observed in the cells exposed to HHT. The cell cycle analysis measured by flow cytometry showed G1 phase cells decreased with the increase of S phase cells while apoptosis was induced by HHT in K562 cells. The percentage of apoptotic cells in K562 cells treated with 50 μg/ml of HHT decreased significantly when pretreated with 1 μg/ml of cycloheximide, 0.05 μg/ml of Actinomycin D respectively.Conclusions HHT has apoptotic effects on K562 cells. The HHT induced apoptosis mainly of the cells in G1 phase and this process required RNA transcription and protein synthesis.

CHARACTERIZATION OF A HUMAN HERPES VIRUS－6（HHV－6） AND EPSTEIN－BARR VIRUS（EBV） ASSOCIATED LEUKEMIC CELL LINE，J6－1

This report characterizes the J6-1 cell line derived from a Chinese acute myelomonocytic leukemia patient and previously reported to be associated with EBV. These studies showed that J6-1 cells were also infected with HHV-6 as demonstrate at the DNA level by PCR and Southern blot hybridization and by expression of HHV-6 early membrane antigen on the J6-1 cell surface. Further characterization showed J6-1 was co-infected with EBV type 2. Generally, cells infected with EBV type 2 do not grow well in vitro. However, J6-1 , although difficult to maintain in vitro, has been grown for 15 years. Possibly, co-infection with HHV6 confers this property. In this regard, J6-1 cells exhibited density dependent growth which could be inhibited with an anti-HHV-6-MA monoclonal antibody(MAb). In contrast, anti-HHV-6-VCA MAb stimulated the J6-1 cell proliferation. Electron microscopic analysis showed that, morphologically, there were two types of J6-1 cell, one with lymphoblastoid features and one with a monocytoid appearance. Accordingly, the flow profile of the J6-1 cell line showed heterogeneity. with two populations comprised of CD15-, CD19+ cells with low light scatter(small cells) and a population with greater light scatter(larger cells) which was CD15+ , CD19+. The population was negative for progenitor cell markers(CD33, 34 ), and T cell markers. Southern analysis showed no T cell receptor rearrangement, however there was a clonal JH and kappa light chain expressing population. Glycocytochemical analysis showed several endogenous lectin receptors on the J6-1 cell surface: BSA-Xylose, BSA-Rhamnose, BSAGal. BSA-Lac. This cell line shares many characteristics with other monocytic/ lymphoblastoid cell lines isolated elsewhere and provides circumstantial evidence linking Herpes viruses, as least as co- factors,to leukemia cell growth.

Expression of the human multidrug resistance gene mdr1 in leukemic cells and its application in studying P-glycoprotein antagonists

Objective To investigate the retrovirus mediated transfer and expression of multidrug resistance gene (mdr1) in hematopoietic cells and to develop a model for studying the possible reversal of the MDR mediated phenotype Methods A retroviral vector HaMDR expressing the human mdr1 gene was packaged by PA317 cells with a titer of up to 8 5×10 5CFU/ml K562 leukemia cells were infected with MDR retrovirus, and transfectant K562/MDR cells were generated The integration and expression of the exogenous mdr1 gene in K562/MDR cells were determined by polymerase chain reaction and flow cytometry The reversal ability of P glycoprotein (P gp) antagonists was analyzed by in vitro drug sensitivity, accumulation and efflux of rhodamine 123 (Rh123) in this model Results Transduction with amphotropic MDR retrovirus resulted in integration and expression of the mdr1 gene in the resistant cells, where an aberrant splicing transcript of the mdr1 gene was found The K562/MDR cells displayed a classic MDR phenotype with a 41-78 fold resistance to vincristine and colchicine in comparison with parental K562 cells The drug sensitivity of K562/MDR cells to vincristine can be completely restored by cyclosporin A (CsA, 2?mg/L) and Cremophor EL (CRE 132?mg/L), either individually or in combination ( P <0 05) CsA (3 ?mg/L) can block the efflux pump function of P gp shown by the significantly increased accumulation and efflux reduction of Rh123 in K562/MDR cells Conclusions Retroviral vector HaMDR allows transfection with high level expression of the mdr1 gene in human myeloid progenitor cells K562 The transfected K562/MDR provides a simple, sensitive model for developing antagonists of P gp and studying their mechanism of action

Effects of Bufalin on Up-regulating Methylation of Wilm's Tumor 1 Gene in Human Erythroid Leukemic Cells

Objective To explore the effects of bufalin on inhibiting proliferation, up-regulating methylation of Wilm’ tumor 1 gene (WT1) as well as its possible mechanisms in human erythroid leukemic (HEL) cells. Methods The HEL cells were treated with bufalin at various concentrations to observe cellular morphology, proliferation assay and cell cycle. The mRNA and protein expression levels of WT1 were detected by reverse transcription polymerase chain reaction (RT-PCR), Western blot and immunocytochemistry, DNA methylation of WT1 and protein expression levels of DNA methyltransferase 3a (DNMT3a) and DNMT3b were analyzed by methylation-specific PCR, and Western blot respectively. Results The bufalin was effective to inhibit proliferation of HEL cells in a dose-dependent manner, their suppression rates were from 23.4%±2.1% to 87.2%±5.4% with an half maximal inhibit concentration (IC50) of 0.046 μmol/L. Typical apoptosis morphology was observed in bufalin-treated HEL cells. The proliferation index of cell cycle decreased from 76.4%±1.9% to 49.7%±1.3%. The expression levels of WT1 mRNA and its protein reduced gradually with increasing doses of bufalin, meanwhile, the methylation status of WT1 gene changed from unmethylated into partially or totally methylated. While, the expression levels of DNMT3a and DNMT3b protein gradually increased by bufalin treatment in a dose-dependent manner. Conclusions Bufalin can not only significantly inhibit the proliferation of HEL cells and arrest cell cycle at G0/G1 phase, but also induce cellular apoptosis and down-regulate the expression level of WT1. Our results provide the evidence of bufalin for anti-leukemia, its mechanism may involve in increasing WT1 methylation status which is related to the up-regulation of DNMT3a and DNMT3b proteins in erythroid leukemic HEL cells.

Effects of Danshen Injection(丹参注射液) on Inhibiting Proliferation and Inducing Apoptosis through Down-Regulation of Mutant JAK2 Gene and Its Protein Phosphorylation in Human Erythroid Leukemic Cells

Objective： To explore the effects of Danshen Injection （丹参注射液） on inhibition proliferation, inducing apoptosis and its possible mechanisms on human erythroid leukemic （HEL） cells. Methods： The commercial Chinese patent medicine of Danshen Injection was extracted and isolated from Chinese herb of Salvia miltiorrhiza bung. The inhibition effects of proliferation were assayed by 3-（4,5-dimethylthiazol-2-yl）-2, 5-diphenyltetrazolium bromide （M＇l-r） method in HEL cells treated by Danshen Injection at various concentrations for 48 h. The cellular apoptosis was observed in morphology, analyzed by flow cytometry with annexin V and propidium iodide （PI） staining, and examined by DNA degradation ladder on agarose gel electrophoresis. Meanwhile, the expression levels of mutant Janus kinasez （JAK2） gene and phosphorylation-JAK2 （P-JAK2） protein were detected by allele specific-polymerase chain reaction and Western blot. ]Results： The proliferation of HEL cells was effectively inhibited by Danshen Injection in a dose-dependent manner, with suppression rates from 19.46 ± 2.31% to 50.20 ± 5.21%. Typical apoptosis cells was observed in Danshen Injection treated HEL cells, the rates of annexin V positive cells increased obviously in a dose-dependent manner, as well as the DNA degradation ladder of apoptosis revealed on gel electrophoresis. The expression levels of mutant JAK2 gene and P-JAK2 protein reduced gradually with increasing dosage of Danshen injection. Conclusion： Danshen Injection could not only significantly inhibit the proliferation, but also induce apoptosis in HEL cells; down-regulation of the mutant JAK2 gene and P-JAK2 protein expressions are probably one of its molecular mechanisms.

Effects of inhibition of ubiquitin-proteasome pathway on human primary leukemic cells

Though there were a lot of reports about the totally different responses to the inhibition of ubiquitin-proteasome pathway in different kinds of cell lines, much less has been known about the responses in primary human leukemic cells. In this study, the effects of inhibition of ubiquitin-proteasome pathway on human bone marrow (BM) mononuclear cells (MNCs) obtained from 10 normal persons and 8 leukemia patients were examined. The results showed that the responses obviously varied individually. Among them, BM MNCs in 3 cases of leukemic patients were extremely sensitive, demonstrated by that >90% cells were induced to undergo apoptosis within 24 h, but MNCs in 10 cases of normal persons showed resistance to the inhibition and no apoptosis was observed. Furthermore, Western blots revealed that the Bcl-2 expression was relatively high in the sensitive primary leukemia cells, and especially the cleavage of 26 ku Bcl-2 into a 22 ku fragment occurred during the induction of apoptosis. In contrast, the Bcl-2 expression was either undetectable or detectable but no cleavage of that above was observed in the cells insensitive to the inhibition of the pathway (including BM MNCs in normal persons). Together with the observations on the leukemic cell lines, these findings suggested the correlation of the specific cleavage of Bcl-2 into a shortened fragment with the sensitivity of cells to the inhibition of ubiquitin-proteasome pathway, which provides clues to the further understanding of the mechanisms of that dramatically different responses existing in different kinds of cells to the inhibition of ubiquitin-proteasome pathway.

HPLCASSAY FOR INTRACELLULAR ACCUMULATION OF VERAPAMIL IN VER-RESISTANT HUMAN LEUKEMIC CELL SUSLINES AND THEIR PARENTAL CELL LINES

Objective: To establish a HPLC method using fluorometric detection for quantitatively determinating intracellular accumulation of verapamil (VER). Methods: Chromatography column was packed with spherisorb ODS(250×4.6 mm,10 μm).The mobile phase consisted of the mixture of methanol:NaAC (0.01 mol/L): diethylamine (65:35:0.25). The detect wavelength was 280/310 nm (Ex/Em). Results: The standard curve showed a good correlation between concentration and peak area within the range of 5-50 ng/ml. RSD was 0.86%, and recovery radio of loading sample, 100%. The detection limit for cell sample was 0.2-148 ng/ml. Intracellular accumulation of VER was observed to decrease from a 13 fold to 5 fold in K562/ADM cells, and from a 3.5 fold to 4.3 fold in K562/VER cells and from a 2.1 fold to 6.5 fold in K562/ADM/VER cells, compared with the relevant control cells. Conclusion: HPLC method was proved to be sensitive and specific for using to quantitatively determine the intracellular accumulation of VER.

Curcumin sensitizes quiescent leukemic cells to antimitotic drug 5-fluorouracil by inducing proliferative responses in them

Long-term quiescence or dormancy is a fundamental feature of cancer stem cells(CSCs)that are genetically identical to the malignant clone but constitute the only cells with tumor propagation potential within the overall tumor population.These quiescent cells show significant resistance to radiation and antiproliferative chemotherapy due to distinctive properties that seem to be related to their stem cell-like character.Hence,successful anticancer therapy must consist of approaches that can target not only the differentiated cancer cells,but also the CSCs.Using serum-starved KG1a cell line as an experimental model system of quiescent leukemic cells(QLCs),the present study demonstrates that QLCs exposed to low concentrations of curcumin show high proliferative potential.Furthermore,when subjected to a combination therapy consisting of low concentrations of curcumin and 5-fluorouracil(5-FU),the QLCs displayed a high kill with an increase in the levels of nitric oxide(NO)and reactive oxygen species.These results were further consolidated with the observation of high caspase-3 activity in cells subjected to the combination therapy.This may suggest that low concentrations of curcumin stimulate the QLCs to become mitotically active,thereby sensitizing them to killing by the antimitotic drug,5-FU.

CHARACTERIZING FLUORESCENCE LIFETIME OF NAD(P)H IN HUMAN LEUKEMIC MYELOID CELLS AND MONONUCLEAR CELLS

The aim of this er vito study was to explore the potential of using the fluorescence lifetime of intraellular reduced nicotinamide adenine dinucleotide(phosphate)(NAD(P)H)as a label-free indicator to characterize the di ferencs between human leukemic myeloid cells and normal mononuclear cells(MNC).The steady-state and time-resolved autofuorescence of two human leukemic myeloid cell lines(K562,HL60)and MNC were measured by a spectrofuorimeter.According to excitation-enmission matrix(EEM)analysis,the optimal emission of NAD(P)H in these cells suspensions occurred at 445 nm.Furthermore,the fuorescence lifetimes of NAD(P)H in leukemic myeloid cells and MNC were determined by fitting the time-resolved autofuorescence data.The mean fuorescence lifetimes of NAD(P)H in K562,HL60,and MNC cells were 557±1.19,4.45±0.71,and 7.31±0.60 ns,respectively.There was a significant diference in the mean lifetime of NAD(P)H between leukemic myeloid cells and MNC(p<0.05).The difference was essentally caused by the change in relative concentration of free and protein-bound NAD(P)H.This study suggests that the mean fuorescence lifetime of NAD(P)H might be a potential label-free indicator for differentiating leukemic myeloid cells from MNC.

The Experimental and Clinical Study on the Effect of Curcumin on Cell Cycle Proteins and Regulating Proteins of Apoptosis in Acute Myelogenous Leukemia

To investigate whether the Bcl- 2 gene family is involved in m odulating mechanism of apoptosis and change of cell cycle protein induced by curcumin in acute myeloid leukemia HL - 6 0 cell line and primary acute m yelogenous leukem ic cells,the Bcl- 2 family member Mcl- 1,Bax and Bak and cell cycle proteins including P2 7kipl,P2 1wafl,cyclin D3and p Rbp- were selected and their ex- pression detected by SABC imm uno- histochem ical stain m ethod.The attitude of sub- G1 peak in DNA histogram was determined by FCM.The TU NEL positive cell percentage was identified by term inal deoxynucleotidyl transferase (Td T ) - m ediated Biotin d U NP end labeling technique.It was found that when HL - 6 0 cells were treated with 2 5μm ol/ L curcumin for 2 4 h,the expression level of Mcl- 1was down- regulated,but that of Bax and Bak up- regulated time- dependently.There was significant difference in the expression level of Mcl- 1,Bax and Bak between the curcumin- treated groups and control group(P<0 .0 5 - 0 .0 1) .At the sam e time,curcumin had no effect on progress of cell cycle in prim aty acute m yelogenous leukemia at newly diagnosis,but could in- crease the peak of Sub- G1 (P<0 .0 5 ) ,and down- regulate the expression of Mcl- 1and up- regulate the expression of Bax and Bak with the difference being statistically significant.The expression of P2 7kipl,P2 1wafl and p Rbp- were elevated and thatof cyclin D3decreased in the presence of curcum in. These findings suggested thatthe Bcl- 2 gene fam ily indeed participated in the regulatory process of apoptosis induced by curcumin in HL - 6 0 cells and AML cells.Curcumin can induce apoptosis of primary acute myelogenous leukemic cells and disturb cell cycle progression of HL - 6 0 cells.The m echanism appeared to be m ediated by perturbing G0 / G1 phases checkpoints which associated with up- regulation of P2 7kipl,P2 1wafl and p Rbp- expression,and down- regulation of cyclin D3.

DIFFERENTIAL EXPRESSION OF GENES INVOLVED IN METABOLISM BETWEEN TUMORIGENITIC HUMAN LEUKEMIA CELL LINES K562 AND K562-n

Objective: To study the molecular mechanism ofdifferent tumorigenicity in nude mice of human leukemiacell lines K562-n and K562. Methods: To analyze the genes differently expressed between K562 and K562-n cells byusing cDNA microarray technique. Results: Among the12800 genes detected, some genes involved in materialmetabolism and material transport were differentlyexpressed between K562-n and K562 cells. These genesinclude homo sapiens placenta-specific ATP-binding cassette transporter gene, dihydrodiol dehydrogenase gene, hepatic dihydrodiol dehydrogenase gene, NAD-dependent methylene tetrahydrofolate dehydrogenase cyclohydrolase,lysophosphatidic acid acyltransferase, alpha gene,argininosuccinate lyase gene, mitochondrial isocitrtatedehydrogenase, adhesion protein SQM1 gene, dimethylarginine dimethylamino-hydrolase gene, M1subunit of ribonucleotide reductase and farnesylpyrophosphate synthetase gene. Conclusion: The hightumorigenicity of K562-n cells is related to the differentexpression of some genes concerned with cell metabolismand material transpoert.

ESTABLISHMENT OF K562/ADM/VER CELL SUBLINE RESISTANT TO VERAPAMIL AND ITS RESISTANT MECHANISM

Objective: To understand whether verapamil (VER) resistance development in the multidrug-resistant cell line and its mechanism. Methods: K562/ADM/VER cell subline resistant to verapamil was established through a gradual increase of VER concentration in the media. MTT method was used to assay resistance to VER, cross resistance to dipyriamole (DPM), cyclosporin A (CsA) in the cells, and HPLC and spectrofluorometer to detect intracellular accumulation of VER or ADM respectively, as well as S-P immunocytochemical technique for detection of genes expression. Results: It were observed that 7.9—fold increase in VER resistance, significantly reduced intracellular accumulation of VER or ADM and also develop across resistance to DPM and CsA in K562/ADM/VER cells, compared with its parent cell, K562/ADM. High-level of p-glycoprotein(pgp), middle-level of p53, p16, was present in two cell lines without expression of GSTPI, C-myc, C-myc, C-fos and C-erbB-2. Bc1–2 protein expression was found only in K562/ADM cells. Conclusion: K562/ADM cells were capable of being induced to develop resistance to VER.

Apoptosis of Leukemia Cells Induced by CD34^+ Cells Transferred Exogenous Fas Ligand

To assess the value of CD34 + cells transferred exogenous Fas ligand (FasL) in inducing apoptosis of human leukemic cells, the CD34 + cells transfected with F asL or without, pretreated with mitomycin C, was mixed with leukemic cell line U937 cells in presence or absence of daunorubicin (DNR) or cytosine arabinoside (Ara C). After l8 h, apoptosis of cells was detected by FCM and TUNEL. Induced for l8 h by CD34 + cells transfected with FasL or without, the ratio of apoptos is of U937 cells was (5.0±1.3) %, (10.8±0.6) % ( P < 0.01), respectively. Induced by FasL +CD34 ++DNR, FasL +CD34 ++Ara C, the ratio was (13.4±1.0) % ( P < 0.05), (17.9±1.3)% ( P <0.01), respectively. The result demonstrated that CD34 + cells transfected with exogenous FasL could induce apoptosis of human leukemic cells and showed a cytotoxic synergistic effect when used in combination with chemotherapeutic drugs, suggesting that it was possible to develop a new method in treatment of leukemia.

The effects of IL-10 on acute leukemic immune evasion

Objective: To explore the effects of IL-10 on acute leukemic immune evasion.Methods: Plasma concentrations of IL-10 were measured by ELISA in 56 first-visit acute leukemic patients.And expressions of IL-10 on leukemic cells in 30 patients were measured by indirect immunofluorescence technique. Results:Compared with those in control group,IL-10 concentrations increased significantly in first-visit acute leukemic patients.And there was a slight but not significant decrease of IL-10 in patients with acute lymphocytic leukemia(ALL) compared with those with acute non lymphocytic leukemic(ANLL).After intensive chemotherapy,there was a significant decrease of IL-10 in completely remitted(CR) patients,especially in those with ANLL,but there was still a significant increase compared with those in control group.The positive rate of cells giving out yellow-green bright fluorescence on membranes was 10%-80%;there were 18 patients expressing IL-10(18/30,60%) positively:among them 11 with ANLL(11/19,58%) and 7 with ALL(7/11,64%) respectively while that of peripheral mononucleate cells in control group was 13%.Compared with that in control group,there was a significant increase of positive rate in ANLL and ALL but with no significant difference between ANLL and ALL.Conclusion: Probably as one of important mechanisms of acute leukemic immune evasion,IL-10 secreted by leukemic cells,contributing to the immunosuppressive state at the tumor site,increase significantly in acute leukemic patients.