NCI CANCERLIT^® Search: Diagnosis-Histopathology-Pathogenesis of AML - September 2001

Last Modified: November 1, 2001

Effects of vascular endothelial growth factor on acute myelogenous leukemia blasts.
MDR-1 expression and deletions of chromosomes 7 and 5(Q) separately indicate adverse prognosis in AML.
Quantification of WT1 mRNA by competitive NASBA in AML patients.
Molecular cytogenetic characterization and clinical relevance of additional, complex and/or variant chromosome abnormalities in acute promyelocytic leukemia.
DNA repair in the MYC and FMS proto-oncogenes in ultraviolet light-irradiated human HL60 promyelocytic cells during differentiation.
Gamma-interferon (IFN-gamma) augments apoptotic response to mistletoe lectin-II via upregulation of Fas/Fas L expression and caspase activation in human myeloid U937 cells.
Rearrangement of the myeloid-lymphoid leukaemia gene in Hong Kong Chinese children with acute leukaemia.
Sphingolipid metabolic changes during chiral C2-ceramides induced apoptosis in human leukemia cells.
Cytokine induction of a human acute myelogenous leukemia cell line (KG-1) to a CD1a+ dendritic cell phenotype.
Loss of heterozygosity in childhood de novo acute myelogenous leukemia.
K562 erythroleukemic cells are equipped with multiple mechanisms of resistance to lysis by complement.
Engineering dendritic cell grafts for clinical trials in cellular immunotherapy of cancer: example of chronic myelogenous leukemia.
Microsatellite instability occurs in defined subsets of patients with acute myeloblastic leukaemia.
Calcium ionophore: a single reagent for the differentiation of primary human acute myelogenous leukaemia cells towards dendritic cells.

CancerMail from the National Cancer Institute

1
UI - 21174301
AU - Foss B; Mentzoni L; Bruserud O
TI - Effects of vascular endothelial growth factor on acute myelogenous leukemia blasts.
SO - J Hematother Stem Cell Res 2001 Feb;10(1):81-93
AD - Institute of Medicine, The University of Bergen and Haukeland University Hospital, N-5021 Bergen, Norway.
Vascular endothelial growth factor (VEGF) and its specific receptors are expressed by various malignant cells, including acute myelogenous leukemia (AML) blasts. In this study we performed a detailed characterization of VEGF effects on native human AML blasts derived from a large group of consecutive AML patients with high blast counts in peripheral blood. Exogenous VEGF had divergent effects on spontaneous proliferation and cytokine-dependent (GM-CSF, G-CSF, IL-3) proliferation. Increased, decreased, or unaltered proliferation was observed in the presence of VEGF for various patients, and the VEGF effect differed even in the same patient depending on which exogenous cytokine being present together with VEGF. Similarly, increased, decreased or unaltered interleukin-1beta (IL-1beta) and IL-6 secretion was detected when VEGF was added, and for certain patients the effect of VEGF differed between IL-1beta and IL-6. Exogenous VEGF could also modulate proliferation and differentiation of clonogenic AML progenitors. Constitutive AML blast secretion of VEGF was detected for 40% of patients. Leptin, Flt3-L, IL-4, IL-10, and IL-13 had divergent effects on VEGF release by AML blasts. These results suggest that VEGF can modulate AML blast functions in vivo for a subset of patients. Furthermore, the detection of VEGF in peripheral blood stem cell (PBSC) autografts suggests that VEGF may influence the proliferation and possibly also the survival of contaminating AML cells in PBSC autografts. We conclude that VEGF may influence the functional characteristics of AML cells. Our results suggest that VEGF is important in leukemic hematopoiesis, and the detection of VEGF in PBSC autografts indicates that VEGF may influence the functional phenotype of contaminating AML cells in these grafts.

2
UI - 21319826
AU - Baldus C; Fietz T; Rieder H; Schwartz S; Thiel E; Knauf W
TI - MDR-1 expression and deletions of chromosomes 7 and 5(Q) separately indicate adverse prognosis in AML.
SO - Leuk Lymphoma 2001 Feb;40(5-6):613-23
AD - Klinikum Benjamin Franklin, Free University Berlin, Germany.
In order to assess any correlation between MDR-1 expression and chromosomal aberrations, and to define their impact on clinical outcome in newly diagnosed AML pts, we investigated bone marrow and peripheral blood samples of 49 consecutive pts admitted to our hospital. Monosomy 7, trisomy 8 and 5q- were evaluated by means of interphase fluorescence in situ hybridization (FISH). Monosomy 7 was present in 6 pts, trisomy 8 in 5 pts, and 5q- in 6 pts. More than one aberration was seen in 7 pts. Chromosomal aberrations were mostly found in older pts (12/14 >60 years; p=0.03) and in pts with CD34 positive leukemic blasts (13/14 coexpressed CD34, p=0.0004). In 25 pts also standard G-banding analysis was performed leading to concordant results regarding chromosomes 7, 8 and 5. Flow cytometry identifyed MDR-1 positivity (MDR+) in 16 pts. MDR-1 expression appeared to be a characteristic feature in CD34+ AML (12/16 were CD34+ and MDR+ pts; p=0.013). No correlation, however, was found between chromosomal aberrations and MDR-1 expression. Pts with aberrations of either chromosomes 7, 8 or 5 detected by FISH (FISH+) were predominantly resistant to induction therapy (6/8 pts, p=0.004). A lower rate of complete remission (CR) was also seen in pts with MDR-1 expression (p=0.006). MDR+/FISH+ pts (n=3) were all refractory to remission induction, while all MDR-/FISH- pts (n=19) achieved CR (p=0.0006). MDR-1+ as well as pts with aberrations of chromosomes 7, and 5(q) showed a significantly decreased probability of overall survival. In conclusion, MDR-1 expression as well as abnormalities of chromosomes 7, and 5(q) predict poor clinical outcome in AML. The identification of these prognostic factors provides useful information for risk adapted treatment strategies.

3
UI - 21393505
AU - Fukahori S
TI - Quantification of WT1 mRNA by competitive NASBA in AML patients.
SO - Kurume Med J 2001;48(2):129-34
AD - Department of Medicine, Kurume University School of Medicine, Kurume 830-0011, Japan.
The measurement of Wilms' tumor gene (WT1) mRNA levels by reverse transcriptase-polymerase chain reaction (RT-PCR) is useful in detecting minimal residual disease (MRD) in leukemia patients. In the present study, we quantified the level of WT1 mRNA in the peripheral blood and bone marrow of patients with acute myelocytic leukemia (AML) at initial onset, remission and recurrence by the use of nucleic acid sequence based amplification (NASBA), and then ascertained the clinical usefulness of this method. At initial onset, the level of WT1 mRNA in the peripheral blood was above 10(3) copies/microgram and that in the bone marrow was above 10(4) copies/microgram. The level of WT1 mRNA was decreased in cases where therapy resulted in complete remission, but it was abnormally high in recurring cases. In AML (M3) patients, the relationship between the level of WT1 mRNA and the expression of the PML-retinoic acid alpha receptor (RAR alpha) gene, assessed by fluorescence in situ hybridization (FISH), was investigated. When leukemia was in remission hematologically, the PML-RAR alpha gene was negative and the level of WT1 mRNA decreased. These findings suggest that the quantification of WT1 gene expression by competitive NASBA is useful in assessing therapeutic effects and detecting MRD.

4
UI - 21406917
AU - Xu L; Zhao WL; Xiong SM; Su XY; Zhao M; Wang C; Gao YR; Niu C; Cao Q; Gu BW; Zhu YM; Gu J; Hu J; Yan H; Shen ZX; Chen Z; Chen SJ
TI - Molecular cytogenetic characterization and clinical relevance of additional, complex and/or variant chromosome abnormalities in acute promyelocytic leukemia.
SO - Leukemia 2001 Sep;15(9):1359-68
AD - Shanghai Institute of Hematology, Rui Jin Hospital, Shanghai Second Medical University, PR China.
Acute promyelocytic leukemia (APL) is characterized by typical morphological manifestation, t(15;17) translocation and active response to all-trans retinoic acid (ATRA) in the great majority of patients. However, a subset of APL cases may present atypical phenotypic, cytogenetic or molecular features at different stages of the disease. The biological and clinical significance of these features sometimes remains obscure. In this study, 284 APL patients were cytogenetically analyzed and precise diagnosis was performed according to the molecular cytogenetic results. Twenty-six APL patients were identified as having additional, complex and/or variant chromosomal abnormalities at diagnosis or at relapse, 16 of them being further analyzed using fluorescence in situ hybridization (FISH) or chromosome painting (CP). Interestingly, some of these chromosomal aberrations were found to be associated with atypical morphology and/or drug response, indicating a genotype-phenotype correlation. Analysis of the complex karyotype may also allow a better understanding of the levels of cellular origin of the leukemogenesis. Examination of the remission induction and survival data showed that the presence of the additional/complex chromosome abnormalities was related to the prognosis in both primarily diagnosed and relapsed patients in this series.

5
UI - 95112290
AU - Islas AL; Hanawalt PC
TI - DNA repair in the MYC and FMS proto-oncogenes in ultraviolet light-irradiated human HL60 promyelocytic cells during differentiation.
SO - Cancer Res 1995 Jan 15;55(2):336-41
AD - Department of Biological Sciences, Stanford University, California 94305-5020.
In order to better understand the role of transcription in cellular processing of damage in specific DNA sequences, we have used an in vitro differentiation system to modulate the activity of the MYC gene. When human HL60 promyelocytic cells differentiate in vitro, the transcriptional activity of the MYC gene is down-regulated. We have shown that in the expressed MYC gene, 56% of UV-induced cyclobutane pyrimidine dimers (CPDs) are removed within 18 h and the transcribed strand is selectively repaired. However, late in differentiation, when the MYC gene is maximally down-regulated, only 15% of the CPDs are removed within the same period. During early differentiation, the MYC gene is regulated by a block to transcription elongation at the 5' end of the first intron. Our results reveal no significant difference in the rate of CPD removal between the restriction fragments upstream and downstream of this elongation block. Furthermore, both strands of each fragment exhibit similar repair characteristics. In contrast, the constitutively expressed FMS gene exhibits proficient removal of CPD in both the differentiated and undifferentiated cells. Furthermore, the repair appears to be more proficient at the 5' end (exon 1) than in the 3' end of the gene about 35 kilobases downstream from exon 1. Since efficient repair of the active FMS gene is maintained in the differentiated cells the loss of repair competence seen in MYC is more likely associated with its reduced transcriptional activity than with a decrease in the overall repair capacity of the terminally differentiated cells.

6
UI - 21220014
AU - Kim MS; Lee J; So HS; Lee KM; Jung BH; Chung SY; Moon SR; Kim NS; Ko CB; Kim HJ; Kim YK; Park R
TI - Gamma-interferon (IFN-gamma) augments apoptotic response to mistletoe lectin-II via upregulation of Fas/Fas L expression and caspase activation in human myeloid U937 cells.
SO - Immunopharmacol Immunotoxicol 2001 Feb;23(1):55-66
AD - Institute of Medical Science, Wonkwang University School of Medicine, Korea.
Mistletoe lectin-II, a major composition of Korean mistletoe (Viscum album coloratum), is known as a potent apoptosis inducer. The previous research has demonstrated that Korean mistletoe lectin-II induces apoptosis via c-Jun N terminal kinase (JNK) activation in human myeloid U937 cells. The purpose of this research is to prove the synergistic action of mistletoe lectin-II and interferon-gamma (IFN-gamma) in the apoptotic cytotoxicity of U937. When U937 cells were treated with mistletoe lectin-II after being differentiated by IFN-gamma, the proteolytic activity of caspase-3 and 9 was markedly elevated and that of caspase-8 was prolonged for 18 hr. The activation of caspase-3-like protease requires the earlier cleavage of poly(ADP-ribose) polymerase(PARP). Caspase-1 was, however, not activated during the resting phase and nor in IFN-gamma-differentiated U937 cells. Western blot analysis revealed that, in IFN-gamma-differentiated U937 cells, the expression of Fas (CD95/APO-1) & Fas ligand(FasL) increases the apoptotic sensitivity against Mistletoe lectin-II. Fas (CD95/APO-1) & FasL were not significantly induced solely by mistletoe lectin-II. Furthermore the activity of JNK1 in U937 cells was also markedly increased with IFN-gamma-differentiation, compared to that of the control. These results suggest that the IFN-gamma-differentiation of U937 cells increases the susceptibility to mistletoe lectin-II-induced apoptosis.

7
UI - 21299398
AU - Lit BM; Wong KF; Kwong YL
TI - Rearrangement of the myeloid-lymphoid leukaemia gene in Hong Kong Chinese children with acute leukaemia.
SO - Hong Kong Med J 2001 Mar;7(1):9-14
AD - Department of Pathology, Queen Elizabeth Hospital, 30 Gascoigne Road, Kowloon, Hong Kong.
OBJECTIVE: To determine the frequency of rearrangement of the myeloid-lymphoid leukaemia gene in acute leukaemia in Hong Kong Chinese children. DESIGN: Immunophenotyping, cytogenetic, and molecular analysis. SETTING: Regional hospital, Hong Kong. PARTICIPANTS: Bone marrow or peripheral blood samples were taken from 27 children aged 16 years or younger with acute leukaemia, from September 1995 through February 1998. MAIN OUTCOME MEASURES: Gene rearrangement was analysed by Southern blotting of HindIII digestion products of mononuclear cell DNA, followed by hybridisation with the myeloid-lymphoid leukaemia P/S4 probe. Nested reverse transcription-polymerase chain reaction analysis was performed to detect and characterise duplication of the myeloid-lymphoid leukaemia gene. RESULTS: Only one (4%) of 23 children whose marrow or peripheral blood samples contained adequate material for genetic study showed rearrangement in the myeloid-lymphoid leukaemia gene. No children were positive for partial tandem duplication of the myeloid-lymphoid leukaemia gene. CONCLUSION: Myeloid-lymphoid leukaemia gene rearrangement is rare in Hong Kong Chinese children with acute leukaemia.

8
UI - 21236225
AU - Baek MY; Yoo HS; Nakaya K; Moon DC; Lee YM
TI - Sphingolipid metabolic changes during chiral C2-ceramides induced apoptosis in human leukemia cells.
SO - Arch Pharm Res 2001 Apr;24(2):144-9
AD - College of Pharmacy, Chungbuk National University, Chongju, Korea.
N-acetylsphingosine (C2-ceramide) is a synthetic water-soluble ceramide mimicking the activity of natural ceramides. By fixing chiral conformation on carbon numbers 2 and 3 in the ceramide structure, four chiral C2-ceramides naming d-erythro-, l-erythro-, d-threo- and l-threo C2-ceramide were synthesized. We have investigated the chiral effects of these C2-ceramides on the sphingolipid metabolism, particularly on both the sphingolipid biosynthetic pathway and on the degradation pathway. In both HL-60 and U937 cells, the chiral C2-ceramide (10 microM) showed sphingosine accumulation monitored fluoromatrically by a high performance liquid chromatographic separation of the sphingoid bases. Most importantly, in HL-60 cells, l-erythro C2-ceramide induced a 50 fold increase in sphingosine as compared to the control, while l-threo C2-ceramide exhibited a minimal 7-fold increase. In contrast, sphinganine, another sphingoid base, showed less accumulation by any chiral C2-ceramide tested under the same conditions. These results suggested that chiral C2-ceramide primarily acts on the sphingolipid degradation pathway rather than on the sphingolipid biosynthetic route. The strong G0/G1 phase arrest in the cell cycle by treatment of l-erythro C2-ceramide indicates that the blockade of the sphingolipid degradation pathway might be concomitantly involved in the dysfunction of the cell cycle. On the other hand, the fact that all chiral C2-ceramides tested failed to inhibit the activity of sphingosine kinase acting on the removal of sphingosine by producing sphingosine-l-phosphate demonstrates that chiral C2- ceramides may increase sphingosine by activating various ceramidases by which natural ceramides are divided into sphingosine and free fatty acids. However, the precise steps involved in this interaction are still unknown.

9
UI - 21256880
AU - Hulette BC; Rowden G; Ryan CA; Lawson CM; Dawes SM; Ridder GM; Gerberick GF
TI - Cytokine induction of a human acute myelogenous leukemia cell line (KG-1) to a CD1a+ dendritic cell phenotype.
SO - Arch Dermatol Res 2001 Mar;293(3):147-58
AD - Procter & Gamble Company, Miami Valley Laboratories, Cincinnati, Ohio 45253-8707, USA.
Dendritic cells (DC) are highly specialized antigen-presenting cells located in many nonlymphoid tissues, and Langerhans cells (LC), a specialized form of DC, are found in the skin. LC as antigen-presenting cells play a critical role in the induction of allergic contact dermatitis. LC research is difficult because few LCs can be isolated from human skin, so efforts have focused on obtaining DCs from alternative sources. Mononuclear cells from peripheral blood and CD34+ stem cells from human cord blood and marrow can be induced to form phenotypic and functional DCs, but experiments of this type are expensive and the DC yield is low. We report here the induction of the myeloid leukemia cell line (KG-1) to a DC morphology and phenotype by culturing the cells in a defined cytokine cocktail. Morphologically, the KG-1-derived DCs are large irregularly shaped cells with prominent dendritic processes and hair-like cytoplasmic projections. Phenotypically, the KG-1-derived DCs lack lineage-specific markers, and express MHC class II, costimulatory molecules CD80 and CD86, and CD83. Functionally, KG-1-derived DCs are capable of phagocytosing latex microspheres and are able to induce a potent allogeneic T-cell response. Within the KG-1-derived DCs, a subpopulation maintains the DC phenotype and morphology described above but further develops CD1a+ marker expression similar to that of resident skin-derived LCs. These findings illustrate that phenotypic, morphologic and functional DCs can be derived from the KG-1 cell line.

10
UI - 21384781
AU - Sweetser DA; Chen CS; Blomberg AA; Flowers DA; Galipeau PC; Barrett MT; Heerema NA; Buckley J; Woods WG; Bernstein ID; Reid BJ
TI - Loss of heterozygosity in childhood de novo acute myelogenous leukemia.
SO - Blood 2001 Aug 15;98(4):1188-94
AD - Fred Hutchinson Cancer Research Center, Seattle, WA 98109-1024, USA. dsweetse@fhcrc.org
A genome-wide screening for loss of heterozygosity (LOH), a marker for possible involvement of tumor suppressor genes, was conducted in 53 children with de novo acute myelogenous leukemia (AML). A total of 177 highly polymorphic microsatellite repeat markers were used in locus-specific polymerase chain reactions. This comprehensive allelotyping employed flow-sorted cells from diagnostic samples and whole-genome amplification of DNA from small, highly purified samples. Nineteen regions of allelic loss in 17 patients (32%) were detected on chromosome arms 1q, 3q, 5q, 7q (n = 2), 9q (n = 4), 11p (n = 2), 12p (n = 3), 13q (n = 2), 16q, 19q, and Y. The study revealed a degree of allelic loss underestimated by routine cytogenetic analysis, which failed to detect 9 of these LOH events. There was no evidence of LOH by intragenic markers for p53, Nf1, or CBFA2/AML1. Most lymphocytes lacked the deletions, which were detected only in the leukemic myeloid blast population. Analysis of patients' clinical and biologic characteristics indicated that the presence of LOH was associated with a white blood cell count of 20 x 10(9)/L or higher but was not correlated with a shorter overall survival. The relatively low rate of LOH observed in this study compared with findings in solid tumors and in pediatric acute lymphoblastic leukemia and adult AML suggests that tumor suppressor genes are either infrequently involved in the development of pediatric de novo AML or are inactivated by such means as methylation and point mutations. Additional study is needed to determine whether these regions of LOH harbor tumor suppressor genes and whether specific regions of LOH correlate with clinical characteristics. (Blood. 2001;98:1188-1194)

11
UI - 21409936
AU - Jurianz K; Ziegler S; Donin N; Reiter Y; Fishelson Z; Kirschfink M
TI - K562 erythroleukemic cells are equipped with multiple mechanisms of resistance to lysis by complement.
SO - Int J Cancer 2001 Sep15;93(6):848-54
AD - Institute of Immunology, University of Heidelberg, Heidelberg, Germany.
Resistance of tumor cells to lysis by complement is generally attributed to several protective mechanisms. The relative impact of these mechanisms in the same tumor cell, however, has not been assessed yet. We have analyzed the interaction of the human erythroleukemia tumor cell line K562 with human complement. K562 cells express the membrane complement regulatory proteins CD59, CD55 and CD46. As shown here for the first time, K562 also spontaneously release the soluble regulators C1 inhibitor, factor H, and soluble CD59. Complement resistance of K562 cells is augmented upon treatment with PMA, TNF or even with sublytic complement. Unlike TNF and sublytic complement, PMA enhanced the expression of membrane-bound CD55 and CD59 and led to increased secretion of soluble CD59. In addition, we show that complement-resistant K562 cells express a membrane-associated proteolytic activity, higher than the complement-sensitive K562/S cells. Treatment of complement-resistant K562 cells with serine protease inhibitors enhance their sensitivity to complement-mediated lysis. Inhibitors of protein kinase C (PKC) also sensitize K562 cells to complement lysis, implicating PKC-mediated signaling in cell resistance to complement. Neutralization of the CD55 and CD59 but not of CD46 regulatory activity with specific antibodies significantly increases complement-mediated K562 cell lysis. Treatment of K562 cells with a mixture of inhibitory reagents results in a significant additive enhancing effect on complement-mediated lysis of K562. In conclusion, K562 cells resist a complement attack by concomitantly using multiple molecular evasion strategies. Future attempts in antibody-based tumor therapy should include strategies to interfere with those resistance mechanisms. Copyright 2001 Wiley-Liss, Inc.

12
UI - 21363217
AU - Dietz AB; Litzow MR; Gastineau DA; Vuk-Pavlovic S
TI - Engineering dendritic cell grafts for clinical trials in cellular immunotherapy of cancer: example of chronic myelogenous leukemia.
SO - Croat Med J 2001 Aug;42(4):428-35
AD - Stem Cell Laboratory, Mayo Clinic Cancer Center, Rochester, MN 55905, USA. dietz.allan@mayo.edu
Dendritic cells are pivotal regulators of immune reactivity and immune tolerance. The observation that dendritic cells can recruit naive T-cells has invigorated cancer immunology and stimulated clinical trials of dendritic cells in immunotherapy. However, variables inherent in preparation and use of dendritic cell grafts remain to be tested. Here we discuss the role of ex vivo dendritic cell processing for in vivo antigen presentation in clinical trials. As an example of the complexity in a clinical trial of dendritic cell vaccines, we present our ongoing trial in immunotherapy of chronic myelogenous leukemia.

13
UI - 21421103
AU - Das-Gupta EP; Seedhouse CH; Russell NH
TI - Microsatellite instability occurs in defined subsets of patients with acute myeloblastic leukaemia.
SO - Br J Haematol 2001 Aug;114(2):307-12
AD - Division of Haematology, Department of Clinical Laboratory Sciences, University of Nottingham, UK. Emma.das-gupta@nottingham.ac.uk
Using a sensitive fluorescent-polymerase chain reaction technique we looked for microsatellite instability (MSI) as functional evidence of mismatch repair defects in 71 cases of acute myeloblastic leukaemia (AML). MSI was assessed at 11 loci in matched leukaemic and constitutional DNA. Nine out of 71 patients (13%) were found to have MSI. Four of these patients had therapy-related leukaemia and the remaining five were all over the age of 60 years. There was a high incidence of adverse-risk cytogenetics in the patients with MSI, including abnormalities of chromosomes 5 and/or 7. Of the nine cases of t-AML included in this study, four (44%) had MSI. MSI was also seen in five of 51 cases (10%) over the age of 60 years but not in any cases under the age of 60 years with de novo AML. Using a sensitive assay, our results suggest that MSI occurs in two subgroups of patients with AML: those with t-AML and the elderly (> 60 years), but is rare in younger patients.

14
UI - 21421126
AU - Waclavicek M; Berer A; Oehler L; Stockl J; Schloegl E; Majdic O; Knapp W
TI - Calcium ionophore: a single reagent for the differentiation of primary human acute myelogenous leukaemia cells towards dendritic cells.
SO - Br J Haematol 2001 Aug;114(2):466-73
AD - Institute of Immunology, University of Vienna, Austria. Martina.Waclavicek@univie.ac.at
Blood monocytes and CD34(+) haemopoietic progenitor cells, as well as certain leukaemic cell lines, acquire characteristics of mature dendritic cells (DC) after stimulation with calcium ionophore (CI). We studied whether the in vitro treatment of primary human acute myelogenous leukaemia (AML) cells with CI leads to differentiation towards DC. Blast cells derived from nine AML patients were cultured in the presence of either CI or an established differentiation cocktail consisting of granulocyte-macrophage colony-stimulating factor plus interleukin 4 and tumour necrosis factor-alpha for 5-7 d. Microscopic examination revealed that under both conditions, AML cells were shifted along the DC pathway. In seven out of nine cases, CI-cultivation led to a higher proportion of cells with dendritic morphology. The percentage of CD40 and CD86 expressing cells was significantly increased upon CI treatment compared with cytokine-cultured cells. DC molecules as CD80 and CD83 were up-regulated upon calcium mobilization of AML cells in four out of nine samples. In four cases, CI-treated stimulator cells induced an enhanced proliferative allogeneic T-cell response compared with cytokine-treated stimulator cells. In conclusion, these data demonstrate that CI treatment is an alternative in vitro strategy to differentiate human AML cells into DC.