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PubMed1995

AML M1 and M2 with eosinophilia and AML M4Eo: diagnostic and clinical aspects.

AML with eosinophilia belongs to the morphologic cytogenetic entity M1/M2 t(8;21) with the involvement of the genes AML1/ETO. These eosinophils differ only slightly from normal eosinophils with one rare exception i.e. Auer rods in eosinophils which has only been found on peroxidase staining: This subtype belongs to the good prognosis group of AML. AML with inv(16) (mostly M4Eo) per se is a morphologic-cytogenetic entity with inv(16),--rarely t(16;16), and the genes MYL 11/CBF beta involved. The eosinophils show special abnormalities. AML with inv(16) also belongs to the good prognosis group of AML.

Bone Marrow↗

PubMed2000

Trisomy 11 acute myeloid leukemia: 5 additional cases from the Japan Adult Leukemia Study Group AML-92 and AML-95 databases.

We searched for trisomy 11 in acute myelogenous leukemia (AML) patients using the Japan Adult Leukemia Study Group (JALSG) AML-92 and -95 databases to clarify the clinical and hematologic features of a rare numerical chromosome abnormality. Among the sequentially registered patients of JALSG AML-92 (655 patients) and JALSG AML-95 (531 patients), chromosome findings were obtained for 1074 patients (90.6%); we found 5 patients with trisomy 11 as the sole abnormality. The patients were 4 women and 1 man with trisomy 11 AML, all aged more than 45 years (median, 52 years), with 4 M1 morphologies and 1 M2. No patients manifested hepatosplenomegaly or lymph node enlargement, and no central nervous system leukemia or extramedullary lesions were detectable. All showed positivity for CD13 (5/5), CD33 (5/5), CD34 (3/3), CD38 (2/2), and HLA-DR (5/5). Except for 1 patient, all achieved complete remission after 1 course of induction chemotherapy, but 2 relapsed after discontinuation of chemotherapy. A third case of relapse occurred during intensification of chemotherapy, and the patient underwent allogenic bone marrow transplantation but died from interstitial pneumonia.

Acute Disease↗

PubMed1992

Acute myeloid leukemia (AML) in Down's syndrome is highly responsive to chemotherapy: experience on Pediatric Oncology Group AML Study 8498.

The treatment of acute myeloid leukemia (AML) in children with Down's syndrome (DS) has engendered considerable controversy. Because of the concerns for toxicity and increased rate of infections, treatment approaches varied considerably in the past with mixed results. However, experience on the recently completed Pediatric Oncology Group (POG) 8498 AML study suggests that DS children with AML constitute a distinct subgroup that responds well to therapy. Twelve of 285 children on POG 8498 (protocol for newly diagnosed AML) had DS. Children with DS and AML were predominantly male (9 of 12) and were quite younger at diagnosis (< 24 months in 10). The white blood cell count was less than 50 x 10(3)/microL in all 12 and French-American-British types M6 and M7 were frequent (5 of 12). An abnormal cytogenetic marker, in addition to constitutional trisomy 21, was present in 9 of 12 and involved chromosome 8 in 4 of 9. All cases studied (n = 5) were positive for myeloid cell surface markers (CD33, CD13, or CD11b) and, interestingly, were also positive for the CD7 antigen. Chemotherapy included daunorubicin, cytarabine (Ara-C), and 6-thioguanine for remission induction and featured high-dose Ara-C (3 g/m2 per dose) with or without L-asparaginase early in remission. Compared with children without DS, children with DS had a superior event-free survival (EFS at 4 years 100% v 28% +/- 6.2%; P = .003). The EFS remained superior even when compared with non-DS children less than 2 years of age with a white blood cell count less than 10 x 100,000/microL (100% v 48% +/- 17.3%; P = .01).

Acute Disease↗

PubMed1992

Treatment results of three consecutive German childhood AML trials: BFM-78, -83, and -87. AML-BFM-Group.

Acute myelogenous leukemia (AML) represents a heterogenous group of leukemias in adults as well as in children. The BFM group initiated 3 consecutive studies on the treatment of this disease. Between December 1978 and April 1991, 543 children under the age of 17 years entered the 3 consecutive multicenter studies, AML-BFM-78 (n = 151), AML-BFM-83 (n = 182), and the still ongoing study AML-BFM-87 (n = 210). The treatment strategy of BFM-78 consisted of an eight week induction/-consolidation regimen employing 7 different drugs together with cranial irradiation, followed by continuous maintenance for two years. The main alteration in the second study BFM-83 was the addition of an intensive 8-day ADE induction course (cytosine arabinoside, daunorubicin, etoposide). In the ongoing trial BFM-87 two courses of HD-ARA-C and etoposide are given after consolidation. CR rates were 80% in trials I and II, and 78% in trial III. The probability of a 4.5-year event-free survival was 35%, SD 4% in study I; 49%, SD 4% in study II, and 45%, SD 4% in study III. The probability of a 4.5-year event-free interval (EFI) was increased from 45%, SD 5% in study I to 61%, SD 4% in study II, it is in the same range in study III (58%, SD 5%). Seven of 10 children which underwent bone marrow transplantation (BMT) in 1. CR are still in first CR after a maximum follow-up time of 3.5 yrs. In summary, the addition of HD-ARA-C together with etoposide given after induction/consolidation treatment did not further reduce the incidence of relapses in childhood AML. So far, the results of study BFM-87 are in the same range than those of study BFM-83.

Adolescent↗

PubMed1986

Randomized controlled study of chemoimmunotherapy of acute myelogenous leukemia (AML) in adults with Nocardia rubra cell-wall skeleton and irradiated allogeneic AML cells.

The effect of immunotherapy with Nocardia rubra cell-wall skeleton (N-CWS) on remission duration and survival of adults with acute myelogenous leukemia (AML) was studied in a prospective randomized controlled study. After having been induced into complete remission and having been consolidated, 73 patients were randomized either to maintenance chemotherapy or maintenance chemotherapy plus immunotherapy with N-CWS and irradiated allogeneic AML cells. Thirty-four patients in the chemotherapy group and 32 in the chemoimmunotherapy group were evaluable. Six months after the closure of the study, the immunotherapy showed a borderline beneficial effect on remission duration (P = 0.080) and on survival length (P = 0.098). When the data were analyzed at 30 months after the entry, there was a borderline significant difference in remission duration (P = 0.080) between the two groups, prolonging the 50% remission period by 110 days; but no significant difference in survival length (P = 0.314), although the 50% survival was 168 days longer in the chemoimmunotherapy group. However, there were 4 (18.2%) 5-year relapse-free survivors among 22 patients (11 in each group) who had been diagnosed more than 5 years before the time of the present analysis, and all of them belonged to the chemoimmunotherapy group (P = 0.090). Thus, immunotherapy with N-CWS and irradiated allogeneic AML cells seems to be active in the treatment of adult AML when used for maintenance therapy in combination with chemotherapy.

Adolescent↗

PubMed1994

A newly developed serum-free culture system: clonal growth of human acute myelogeneous leukemia (AML) progenitors--a report of 14 AML cases.

A new serum-free culture (SFC) system for human AML-CFU was established and the colony-promoting activity of four recombinant human hematopoietic growth factors (rhHGFs) including granulocyte-macrophage colony-stimulating factor (rhGM-CSF), interleukin-3 (rhIL-3), erythropoietin (rhEPO) and newly developed stem cell factor (rhSCF) were investigated in this SFC system. Under the orthogonal design condition, it was found that human AML-CFU presented optimal clonal growth in an environment of bovine serum albumin (0.6%), saturated human transferrin (2 x 10(-6) mol/L), cholesterol (2.8 micrograms/ml), bovine insulin (15 micrograms/ml), bovine hemin (0.05 mmol/L), linoleic acid (2.8 micrograms/ml), and IMDM. Spontaneously growing colonies were observed in 11 out of 14 cases studied. The plating efficiencies obtained by culturing with rhGM-CSF, rhIL-3, and rhSCF were 0.776 +/- 0.621%, 0.574 +/- 0.510%, and 0.647 +/- 0.543% (mean +/- s), respectively. There was one case (M3b) showing no response to all HGFs in both SFC ad SCC. The clonal growth of AML-CFU obtained from peripheral blood of the patient with M6 was unexpectedly marked. As a whole, the newly designed SFC system has been demonstrated to be useful for culture of human AML-CFU from both bone marrow and peripheral blood.

Culture Media, Serum-Free↗

PubMed1994

CD14 mediated endogenous TNF-alpha release in HL60 AML cells: a potential model for CD14 mediated endogenous cytokine release in the treatment of AML.

In previous studies, HL60 AML cells treated with tumor necrosis factor-alpha (TNF), interferon-gamma (IFN), and lipopolysaccharides (LPS) displayed decreased growth and viability, enhanced monocytic pathway differentiation and endogenous TNF release. Endogenous TNF release by LPS/TNF/IFN treated HL60 cells was postulated to play a role with the above findings. In these studies, HL60 cells expressed CD14 when treated with TNF, IFN, and LPS. CD14 mediates TNF release in monocytes/macrophages in response to binding of LPS with LPS binding protein (LBP). CD14 was not expressed in either untreated or LPS only treated HL60 cells. CD14 expression was present and greater with HL60 cells cultured with LPS/TNF/IFN vs TNF/IFN (47.47% vs 9.07% positive, respectively) suggesting synergism for LPS in CD14 induction. CD14 expression was associated with endogenous TNF release, and with significantly higher levels by HL60 cells treated with LPS/TNF/IFN vs TNF/IFN (p < 0.001). Addition of anti-CD14 antibody significantly reduced release of TNF in TNF/IFN (p < 0.001) and LPS/TNF/IFN (p = 0.0013) treated cells. KG1 and U937 AML cells treated with LPS, TNF, and IFN did not express CD14, nor release TNF. A model for inducing release of endogenous growth inhibitory cytokines by CD14 bearing AML cells is proposed as an approach to AML therapy.

Antigens, CD↗

PubMed2006

Acute myeloid leukemia (AML) with t(8;21)(q22;q22) relapsing as AML with t(3;21)(q26;q22).

We here report on an 48-year-old male patient with a primary diagnosis of acute myeloid leukemia (AML)-M2 with t(8;21)(q22;q22), who developed complete hematologic and molecular remission after induction chemotherapy. Thirteen months later, he relapsed and showed an AML-M2 with t(3;21)(q26;q22). Retrospectively, polymerase chain reaction (PCR) for AML1-EVI1 and EVI1 overexpression was performed on bone marrow and peripheral blood samples taken at diagnosis and during the first year after the first manifestation of AML to quantify the AML1-EVI1-positive clone. In a bone marrow sample taken 25 days from diagnosis, PCR for AML1-EVI1 was negative, and EVI1 expression, as assessed by quantitative real-time PCR, was within the same range as that of healthy controls. These data suggest that this patient developed a secondary therapy-related AML rather than a relapse.

Chromosomes, Human, Pair 21↗

PubMed2005

IL-2/B7.1 (CD80) fusagene transduction of AML blasts by a self-inactivating lentiviral vector stimulates T cell responses in vitro: a strategy to generate whole cell vaccines for AML.

Combined expression of costimulatory factors and proinflammatory cytokines stimulate effective immune-mediated tumor rejection in a variety of murine tumor models. Specifically, syngeneic tumor cells genetically modified to express B7.1 (CD80) have been shown to induce rejection of previously established murine solid tumors, and transduction with IL-2 can further increase survival. However, poor rates of gene transfer and inefficient expression of multiple transgenes encoded by single vectors have hampered the development of such autologous tumor cell vaccines for clinical trials in acute myeloid leukemia (AML) patients. Here we describe the development of a self-inactivating lentiviral vector encoding B7.1 and IL-2 as a single fusion protein postsynthetically cleaved to generate biologically active membrane-anchored B7.1 and secreted IL-2. This enables the efficient transduction of both established and primary AML blasts, resulting in expression of the transgenes in up to 98% of the cells following a single round of infection at an m.o.i. of 10. The combined expression of IL-2 and B7.1 in AML blasts enables increased stimulation of both allogeneic and autologous T cells. The stimulated lymphocytes secrete greater levels of Th1 cytokines and show evidence of specificity, as indicated by their increased proliferation in the presence of autologous AML compared to remission bone marrow cells.

B7-1 Antigen↗

PubMed1997

What happens subsequently in AML when cytogenetic abnormalities persist at bone marrow harvest? Results of the 10th UK MRC AML trial. Medical Research Council Leukaemia Working Parties.

Cytogenetic analysis performed at diagnosis is widely recognised to provide one of the most valuable prognostic indicators in AML. Yet any role for this technique in residual disease assessment, particularly in the context of subsequent transplantation procedures has been incompletely explored. The present study considers the outcome of 190 patients drawn from the UK MRC AML 10 trial in whom cytogenetics were assessed whilst in morphological CR at the time of bone marrow harvest. Cytogenetics at this stage were abnormal in 19 patients (10%). In 11/19 patients, the abnormalities detected reflected the acquisition of new clonal (3/11) or nonclonal changes (8/11) that were not identified at diagnosis; comparison of this group to patients with normal cytogenetics at harvest provided no evidence that such acquired changes are of prognostic significance. In 8/19 patients, abnormalities detected were indicative of persistence of the disease-related clone in harvested marrow. Two of these patients died of sepsis during consolidation therapy. Two received ABMT in first morphological CR: one patient with AML associated with a favourable karyotype (+8,inv(16)) remains in CR, 5.5 years post-transplant, whereas the other with cytogenetic abnormalities considered to confer a poor prognosis (inv(3q),-7), relapsed within 5 months of ABMT. All four of the remaining patients with cytogenetic evidence of persistent disease who were not transplanted in first CR, relapsed within 6.5 months of harvest. Therefore, among 101 of 190 patients with AML characterised by abnormal karyotype at diagnosis, persistence of the disease-related clone in eight patients (8%), revealed by conventional cytogenetic assessment at bone marrow harvest whilst in morphological remission, was found to predict a poor prognosis. Nevertheless, transplantation procedures using marrow which is obviously contaminated with the original leukaemic clone may occasionally still be associated with long-term survival.

Adolescent↗

PubMed2005

Pediatric Oncology Group (POG) studies of acute myeloid leukemia (AML): a review of four consecutive childhood AML trials conducted between 1981 and 2000.

From 1981 to 2000, a total of 1823 children with acute myeloid leukemia (AML) enrolled on four consecutive Pediatric Oncology Group (POG) clinical trials. POG 8101 demonstrated that the induction rate associated with the 3+7+7 combination of daunorubicin, Ara-C, and 6-thioguanine (DAT) was greater than that associated with an induction regimen used to treat acute lymphoblastic leukemia (82 vs 61%; P=0.02). Designed as a pilot study to determine the feasibility of administration of noncross-resistant drug pairs and later modified to assess the effect of dose intensification of Ara-C during the second induction course, POG 8498 confirmed the high initial rate of response to DAT (84.2%) and showed that dose intensification of Ara-C during the second induction course resulted in a trend toward higher event-free survival (EFS) estimates than did standard-dose DAT (2+5) during the second induction course (5 year EFS estimates, 22 vs 27%; P=0.33). Age <2 years and leukocyte count <100 000/mm3 emerged as significantly good prognostic factors. The most significant observation made in the POG 8498 study was the markedly superior outcome of children with Down's syndrome who were treated on the high-dose Ara-C regimen. POG 8821 compared the efficacy of autologous bone marrow transplantation (BMT) with that of intensive consolidation chemotherapy. Intent-to-treat analysis revealed similar 5-year EFS estimates for the group that underwent autologous BMT (36+/-4.7%) and for the group that received only intensive chemotherapy (35+/-4.5%) (P=0.25). There was a high rate of treatment-related mortality in the autologous transplantation group. The study demonstrated superior results of allogeneic BMT for patients with histocompatible related donors (5-year EFS estimate 63+/-5.4%) and of children with Down's syndrome (5-year EFS estimate, 66+/-8.6%). The POG 9421 AML study evaluated high-dose Ara-C as part of the first induction course and the use of the multidrug resistance modulator cyclosporine. Preliminary results showed that patients receiving both high-dose Ara-C for remission induction and the MDR modulator for consolidation had a superior outcome (5-year EFS estimate, 42+/-8.2%) than did patients receiving other treatment; however, the difference was not statistically significant. These four studies demonstrate the importance of dose intensification of Ara-C in the treatment of childhood AML; cytogenetics as the single most prognostic factor and the unique curability of AML in children with Down's syndrome.

Acute Disease↗

PubMed2003

Cytogenetic heterogeneity of acute myeloid leukaemia (AML) with trilineage dysplasia: Japan Adult Leukaemia Study Group-AML 92 study.

Acute myeloid leukaemia (AML) with trilineage dysplasia (AML/TLD) is de novo AML recognized by the morphological dysplasia of three mature cell lines in the presence of leukaemic blasts. We studied the karyotypes of AML/TLD of patients with de novo AML, except for those with the French-American-British classification M3, who were enrolled onto the Japan Adult Leukaemia Study Group (JALSG)-AML 92 trial. Morphological and cytogenetic analyses were performed in 559 patients and TLD phenotype was found in 155 patients (27.7%). The 511 patients with informative morphological and cytogenetic data were classified into three groups according to karyotype: favourable, intermediate and adverse risk groups (92, 375 and 44 patients respectively). Normal karyotype was the most frequent as a total, and among both the non-TLD and TLD patients (164 patients 45.3% and 78 patients 52.7% respectively). All but one patient with AML/TLD was classified into the intermediate or adverse cytogenetic risk group. TLD phenotype was associated with lower remission rate and shorter overall survival but it did not influence disease-free survival. Although we did not find any specific cytogenetic abnormalities for AML/TLD, the rarity of favourable karyotypes among TLD patients indicates the biological difference between AML/TLD and AML/non-TLD.

Acute Disease↗

PubMed1999

Identification of the t(15;17) in AML FAB types other than M3: evaluation of the role of molecular screening for the PML/RARalpha rearrangement in newly diagnosed AML. The Medical Research Council (MRC) Adult Leukaemia Working Party.

Acute promyelocytic leukaemia (APL) is characterized by the t(15;17) leading to the formation of PML-RARalpha and RARalpha-PML fusion genes; this rearrangement has been considered both diagnostic for, and restricted to, this subtype of acute myeloid leukaemia (AML FAB M3). We describe two cases of AML with the t(15;17) associated with a PML/RARalpha rearrangement which lacked typical APL morphology, classified as FAB M1 and M2 respectively. In both cases morphological review revealed small populations of cells which exhibited some features associated with APL. In the case classified as M1, PML immunofluorescence studies revealed the classic microparticulate nuclear staining pattern as observed in typical cases of APL with the t(15;17). Similarly, blasts from this case were found to be sensitive to ATRA in vitro as determined by NBT reduction test and by normalization of the PML nuclear body staining pattern. To determine the frequency of PML/RARalpha rearrangements in FAB subtypes other than M3, 530 patients from the MRC AML trials were screened using nested RT-PCR. Only one individual, initially classified as M5 with a normal karyotype, was found to have a PML/RARalpha rearrangement. The diagnosis was revised to M3 variant on subsequent morphological review. In conclusion, this study demonstrates that, in rare cases, the t(15;17) is not restricted to patients with M3 morphology as defined by current FAB criteria. Therefore, although we consider cytogenetic analysis of newly diagnosed cases of AML to be mandatory, our data suggests that routine molecular screening for PML/RARalpha rearrangements is not justified and should be reserved for those cases displaying features which may be suspicious of APL even if such cells comprise only a minority of the total population.

Adolescent↗

PubMed2001

Standard anatomical medullary locking (AML) versus tricalcium phosphate-coated AML femoral prostheses.

OBJECTIVES: To compare the preliminary rate and amount of bony ingrowth and calcar resorption between patients receiving either a standard anatomical medullary locking (AML) or a tricalcium phosphate (TCP)-coated AML femoral prosthesis and to compare preliminary clinical results. DESIGN: A prospective, randomized, double-blind clinical trial. SETTING: An acute care tertiary institution. PATIENTS: Between January 1993 and March 1995, 92 patients underwent primary total hip arthroplasty (THA). They were randomized to 2 groups of 46--a control group or a treatment group. Of the 46 subjects enrolled in each group, no significant differences were seen preoperatively with respect to age, sex, diagnosis, clinical and radiographic assessment. Seventy-one patients were followed up for 24 months. INTERVENTIONS: Insertion of either a standard AML femoral implant (control group) or a TCP-coated AML femoral implant (treatment group). OUTCOME MEASURES: The degree of hypertrophy, calcar atrophy and the number of spot welds on standard postoperative radiographs at 6, 12 and 24 months. Clinically, assessment according to the Société internationale de chirurgie orthopédique et de traumatologie (SICOT) scale and a 100-point visual analogue scale (VAS) for pain. RESULTS: There were no prosthetic stem revisions in either group at the 24-month follow-up. Radiographically, bony ingrowth was not significantly different in the TCP-coated stem, by chi2 analysis of the degree of hypertrophy and number of spot welds present. Also by chi2 analysis, the degree of calcar atrophy was not significantly different between groups. The mean VAS score for pain at 24 months was 12.5 for the control and 12.1 for the treatment group. No significant differences were seen in any of the clinical categories of the SICOT Scale over the 24-month interval. CONCLUSION: The objective of TCP-coating--to increase the rate and amount of bony ingrowth while reducing the rate of calcar resorption in non-cemented THA--was not achieved by 24 months postoperatively in our study.

Arthroplasty, Replacement, Hip↗

PubMedDate not supplied

Testing a predictive regression model for response in adult acute myeloid leukemia comparing two induction regimens of the E.O.R.T.C. -AML-5 and AML-6 trial.

Pretreatment characteristics of 295 adults with acute myeloid leukemia who were treated in a large cooperative group of the E.O.R.T.C. between 1976 and 1982 (AML-5) have been evaluated to assess their value as prognostic indicators. Logistic regression methods were applied to derive a model for prediction of achievement of CR. The model was tested prospectively in an independent group of 274 subsequent patients treated with a different but similar induction regimen (AML-6), who were matched in all eligibility criteria. The concordance between the observed percentage of response in the AML-6 trial population and the expected response given by the model built on the AML-5 study was very close for the good response subgroups (WBC less than 50,000/mm3 and age less than 60 yrs), while the discrepancies in the poor prognostic groups were considerable. Furthermore, our study shows that the prognostic value of factors may shift as treatment strategies change and that caution is necessary in applying conclusions from a preceding trial to a current patient population.

Adolescent↗

PubMed1994

AML-1 gene rearrangement and AML-1-ETO gene expression as molecular markers of acute myeloblastic leukemia with t(8;21).

Rearrangements of the AML-1 gene on chromosome 21 as well as transcriptional expression of AML-1-ETO fusion gene were studied in 35 leukemic patients with t(8;21)(q22;q22). A panel of probes generated from the AML-1 gene regions flanking the breakpoint on chromosome 21 allowed us to detect the rearrangement in 24 out of 29 patients. A specific nested reverse transcriptase/polymerase chain reaction (RT/PCR) was developed to detect the t(8;21), either at diagnosis or as minimal residual disease. PCR amplification products were obtained in ten out of 11 patients investigated, and the sensitivity of the reaction was estimated to be between 1 x 10(4) and 1 x 10(-5) cell. An AML-1 rearrangement was also detected in one patient with 8q- and only one chromosome 21, but without 21q+. This indicated that the molecular rearrangement of the der(8) chromosome is more important than the reciprocal one in the malignant process.

Adolescent↗

PubMed2005

In vitro crosstalk between fibroblasts and native human acute myelogenous leukemia (AML) blasts via local cytokine networks results in increased proliferation and decreased apoptosis of AML cells as well as increased levels of proangiogenic Interleukin 8.

Interactions between native human acute myelogenous leukemia (AML) blasts and nonleukemic cells in the bone marrow microenvironment seem important both for disease development chemosensitivity. Native human AML blasts from consecutive patients were cultured with normal human bone marrow stromal cells and two fibroblast lines (HFL1 and Hs27) separated by a semipermeable membrane. This bidirectional crosstalk via the cytokine network between AML blasts and fibroblasts caused (i) increased proliferation, (ii) mediated antiapoptotic signalling and (iii) increased local levels of proangiogenic IL8.

Adult↗

PubMed2002

Expression of Fc(epsilon)-receptors by human acute myelogenous leukemia (AML) blasts: studies of high- and low- (CD23) affinity receptor expression and the effects of IgE-mediated receptor ligation on functional AML blast characteristics.

Acute myelogenous leukemia (AML) blasts derived from 20 patients were examined for expression of high- (Fc(epsilon)RI) and low-affinity (Fc(epsilon)RII, CD23) IgE Fc(epsilon)-receptors. Fc(epsilon)RI expression was not detected for any patient. In contrast, expression of CD23 (at least 15% of the blasts stained positive) was detected for 6 out of the 20 patients. Acute lymphoblastic leukemia (ALL) blasts derived from 12 patients did not express CD23 (<1% positive cells for all patients). The functional effects of Fc(epsilon)R-receptor ligation were also examined for 20 patients, including the five patients with highest CD23 expression (30-55% positive cells) and five patients with verified low CD23 expression (<or=7% positive cells). The presence of IgE during in vitro culture altered the functional characteristics (spontaneous and cytokine-dependent proliferation, colony formation, cytokine secretion, or spontaneous in vitro apoptosis) of AML blasts for a subset of both CD23-positive patients and certain patients with very low CD23 expression. This last observation suggests that Fc(epsilon)R are either expressed at a very low level or receptors are expressed only by a minor cell subset for these patients. We conclude that functional Fc(epsilon)R can be expressed by human AML cells.

Apoptosis↗