Rearrangements of immunoglobulin and T cell receptor beta and gamma genes are associated with terminal deoxynucleotidyl transferase expression in acute myeloid leukemia.

The cell origin of the rare terminal deoxynucleotidyl transferase (TdT)-positive acute myeloid leukemias (AML) was investigated at the molecular level, by examining the configuration of the Ig H (Igh) and L (Ig kappa, Ig lambda) chain gene regions, and of the T cell receptor (TCR) beta and T cell rearranging (TRG) gamma loci. In 8 of the 10 TdT+ AML analyzed (classified as myeloid according to morphological and cytochemical criteria, and to the reactivity with one or more antimyeloid mAbs), a rearrangement of the Igh chain gene was found. In TdT- AML, evidence of an Igh gene reorganization was instead observed only in 2 of the 42 patients studied. Furthermore, evidence of TCR-beta and/or TRG-gamma gene rearrangement was observed in four AML, all of which belonged to the Igh-rearranged TdT+ group. In three cases (one TdT+ and two TdT-), the Ig kappa L chain gene was also in a rearranged position. These findings demonstrate a highly significant correlation between TdT expression and DNA rearrangements at the Igh and TCR chain gene regions and support the view that this enzyme plays an important role in the V-(D)-J recombination machinery. Overall, the genomic configuration, i.e., JH gene rearrangement sometimes coupled to a kappa L chain and TCR gene reorganization, similar to that found in non-T-ALL, suggests that in most cases of TdT+ AML, the neoplastic clone, despite the expression of myeloid-related features, is characterized by cells molecularly committed along the B cell lineage.

Efficient transfer of selectable and membrane reporter genes in hematopoietic progenitor and stem cells purified from human peripheral blood.

We have utilized highly purified hematopoietic progenitor and stem cells (HPCs, HSCs) from normal peripheral blood to develop methodology for: (a) efficient transfer into HPCs of a non-hematopoietic membrane reporter, i.e., the nerve growth factor receptor complementary DNA; and (b) effective gene transduction of putative HSCs, i.e., cells initiating Dexter-type long-term culture (LTC-ICs). Purified HPCs induced into cycling by growth factors (interleukin 3, interleukin 6, c-kit ligand) were transduced with the N2 retroviral vector containing the neomycin resistance (neor) gene. More than 80% of transduced HPCs were resistant to the toxic G418 level. Thereafter, the HPCs were effectively transduced with the LNSN retroviral vector containing a nerve growth factor receptor complementary DNA; the nerve growth factor receptor was detected on > or = 18% of the transduced HPCs. These experiments provide a new tool from which (a) to monitor expression of a transduced membrane report on hematopoietic cells, particularly at the level of HPCs/HSCs, and (b) to characterize the transduced cells by double- and triple-labeling membrane antigen analysis. Purified HPCs/HSCs grown in Dexter-type LTC were transduced at 1 week by exposure to supernatant N2 retroviral particles in the absence of exogenous hematopoietic growth factors. The procedure, devoid of toxic effects, allowed an efficient neor transduction into LTC-ICs. Thus, we consistently detected neomycin-resistant mRNA in the clonal progeny of HPCs produced in LTC at 5-8 weeks in both the nonadherent and adherent fractions; this timing of expression coincides with that of HPC production by LTC-ICs, thereby indicating the effective transduction of the LTC-ICs. These experiments represent a first step toward development of preclinical models for gene transfer into human peripheral blood HSCs by complex retroviral vectors.

Purified autologous grafting in childhood acute lymphoblastic leukemia in second remission: evidence for long-term clinical and molecular remissions.

Autologous transplantation is a treatment option for relapsed childhood acute lymphoblastic leukemia (ALL) in second complete remission (CR2) when a suitable donor is not available. In an attempt to prevent relapses originating from graft leukemic contamination, the experimental protocol of in vitro purification of leukapheretic products with monoclonal antibodies (MoAbs), previously reported for adults, was adopted in 11 of 12 consecutive patients (median age, 9 years) with B cell precursor ALL in CR2 after late relapse (median, 37; range, 31-51 months after the onset) enrolled between July 1997 and July 1999 at a single pediatric center. At a median of 12 days after the mobilizing chemotherapy followed by G-CSF, a median of 13.9 (range, 5.9-18.7) x 10(6) CD34+ cells/kg were collected from each patient and a median of 7.5 (range, 4.1-12.6) x 10(6) CD34+ cells/kg underwent the purification procedure. The first step of immunorosetting allowed a one-log reduction of the total cell count, by eliminating more than 90% of the CD11b+ cells; the second step, performed after incubation with anti-CD19 MoAbs, allowed the depletion of 99% (range, 93-100) of the CD19+ cells, kept within the magnetic field of the immunodepletion column, with a median recovery of 73% (range, 55-87) of the collected CD34+ cells. Molecular analysis assessed the in vitro eradication of detectable leukemic cells. A median reinfusion of 5.2 (range, 3.2-9.1) x 10(6) CD34+ cells/kg for each patient (median viability, 90%), after conditioning with the 'TBI-VP16-CY' regimen, allowed prompt engraftment and immunological reconstitution; no patients experienced severe transplant-related toxicity or major infections. One patient relapsed 7 months after transplantation, while 10 patients are alive in clinical and molecular remission, at a median follow-up of 29 months (range, 15-40) (2-year EFS, 89%, s.e. 9). In conclusion, the procedure proved to be reproducible for pediatric purified autografting, highly efficient concerning stem cell recovery and depletion of leukemia-lineage specific cells, and promising in terms of final outcome.

Leukaemic transformation of donor cells in a patient receiving a second allogeneic bone marrow transplant for severe aplastic anaemia.

Allogeneic blood or bone marrow transplantation is a successful treatment for leukaemia and severe aplastic anaemia (SAA). Graft rejection following transplantation for leukaemia is a rare event but leukaemic relapse may occur at varying rates, depending upon the stage of leukaemia at which the transplant was undertaken and the type of leukaemia. Relapse is generally assumed to occur in residual host cells, which are refractory to, or escape from the myeloablative conditioning therapy. Rare cases have been described, however, in which the leukaemia recurs in cells of donor origin. Lack of a successful outcome of blood or bone marrow transplantation for severe aplastic anaemia (SAA), however, is due to late graft rejection or graft-versus-host disease. Leukaemia in cells of donor origin has rarely been reported in patients following allogeneic bone marrow transplantation for SAA. This report describes leukaemic transformation in donor cells following a second allogeneic BMT for severe aplastic anaemia. PCR of short tandem repeats in bone marrow aspirates and in colonies derived from BFUE and CFU-GM indicated the donor origin of leukaemia. Donor leukaemia is a rare event following transplantation for severe aplastic anaemia but may represent the persistence or perturbation of a stromal defect in these patients inducing leukaemic change in donor haemopoietic stem cells.

Bone marrow transplantation for childhood hematological disorders: a global pediatric approach in a twelve year single center experience.

One hundred and 43 consecutive pediatric patients (June 1985-December 1996) with at least 18 months of follow-up, were considered: most of the patients (111/143, 77.6%) underwent allogeneic BMT. The median follow-up was 5.7 years. Overall survival and 5 years EFS were 48.6% and 46.9%, respectively. For patients who underwent allogeneic BMT from HLA-identical siblings, the 5 years EFS for ALL was 75% in 1st CR, 60.4% in 2nd CR, 22.3% in > 2nd CR and 86.7% for AML in 1st CR. The EFS for Allo-BMT in "good" and "poor" prognosis patients was 68.6% and 21.8%, respectively (p value = 0.001). Early mortality in Allo-BMT patients was 17.7% between 1985-1990 and 10.3% between 1991-1996. Early treatment-related organ complications occurred mostly in patients who underwent BMT from an unrelated or a mismatched family donor. Late toxicity was evaluated in 57 patients (median follow-up of 82 months): none of the patients complained of significant late cardiac or respiratory dysfunction. With regards to growth, 18/57 patients (31.6%) lost more than two height centile channels. Three cases of thyroid neoplasms were observed. Evaluation of psychosocial functioning, studied in 39 patients who had at least 2 years of follow-up in CR, did not reveal any evident quality of life impairment. The possibility of curing childhood hematological malignancies is based on a global pediatric and multidisciplinary approach. A continuous need to improve results in terms of EFS and quality of life suggests that further multicenter prospective studies should be carried out.

Detection of hepatitis B virus DNA sequences in bone marrow of children with leukemia.

To investigate the possibility that hemopoietic cells may become infected with hepatitis B virus (HBV), viral DNA was studied by molecular hybridization in bone marrow aspirates of 51 children with leukemia. HBV-DNA was found in the bone marrow of eight children (15%) and Southern blot analysis revealed the presence of free, monomeric viral sequences. Only one of the eight children with HBV-DNA in bone marrow cells was HBsAg-positive in serum, whereas two additional patients were transiently HBsAg-positive in serum during follow-up, but were negative at the time HBV-DNA was found in bone marrow. Four other cases developed antibodies to HBV. Cases of myeloid leukemia were more frequently positive for HBV-DNA in bone marrow (55%), compared with cases of lymphoid leukemia (7%). These results indicate that hemopoietic cells are susceptible to infection with hepatitis B virus and stimulate new interest into the relation of HBV infection to the development of some forms of leukemia, as four of eight cases of myeloid leukemia were HBV-DNA positive in bone marrow aspirates at diagnosis, prior to receiving any transfusion therapy.

Improved avidin-biotin-peroxidase complex (ABC) staining.

A considerable intensification of the avidin-biotin-peroxidase complex staining system (ABC) was obtained by sequentially overlaying the sections to be immunostained with an avidin-rich and a biotin-rich complex. Each sequential addition contributed to the deposition of horseradish peroxidase on the immunostained site and allowed the subsequent binding of a complementary complex. With this technique a higher dilution of the antisera could be used and minute amounts of antigen masked by the fixative could be demonstrated on paraffin sections.

Bone marrow stroma in humans: anti-nerve growth factor receptor antibodies selectively stain reticular cells in vivo and in vitro.

Two anti-nerve growth factor receptor (LNGFR or p75NGFR) antibodies, Me20.4 and Me8211, label stromal cells with dendritic features in fresh smears and in formalin-fixed, paraffin-embedded human bone marrow (BM). The LNGFR+ cells have an oval nucleus, a scanty cytoplasm with long dendrites that intermingle with the hematopoietic cells, line the abluminal side of sinus endothelial cells, and provide the scaffold for the hematopoietic marrow. At the electron microscopy level, the immunogold tag labels the body and the long branching dendrites of fibroblast-like cells with scanty cytoplasm containing mitochondria, endoplasmic reticulum, and dense bodies. The LNGFR+ cells are positive for alkaline phosphatase, reticulin, collagen III, vimentin, TE-7, and CD13 but negative for endothelial (vWF, CD34, Pal-E), neural (CD56, neurofilament) and leukocyte markers (CD45, CD68). The LNGFR+ stromal cells appear in the fetal BM before the hematopoietic activity begins, originate from the vessel adventitia, and radiate in the Bm cavity. Long-term BM culture (LTBMC) in vitro contain LNGFR+ stromal cells. We document the presence of RNA message for the low- (LNGFR) and the high-affinity NGF receptor (NTRK1) by using RT-PCR on fresh BM aspirate and on LTBMC. BM biopsies from patients with hematologic fibrogenic diseases and in cytokine-treated cancer patients are evaluated for LNGFR+ cells: the amount of stained cells is correlated with the traditional reticulin stain in cases of myelofibrosis, therapy-related myelodysplasia, leukemia, and detected an increase of stromal cells in cytokine-treated patients. The anti-LNGFR antibodies represent a specific membrane marker for the adventitial reticular cells (ARC) of the human marrow and allow precise evaluation and quantitation of this important BM microenvironment component in vivo and in vitro.

Induction of cyclophosphamide-resistance by aldehyde-dehydrogenase gene transfer.

The identification of genes inducing resistance to anticancer chemotherapeutic agents and their introduction into hematopoietic cells represents a promising approach to overcome bone marrow toxicity, the limiting factor for most high-dose chemotherapy regimens. Because resistance to cyclophosphamide has been correlated with increased levels of expression of the aldehyde-dehydrogenase (ALDH1) gene in tumor cell lines in vitro, we tested whether ALDH1 overexpression could directly induce cyclophosphamide resistance. We have cloned a full-length human ALDH1 cDNA and used retroviral vectors to transduce it into human (U937) and murine (L1210) hematopoietic cell lines that were then tested for resistance to maphosphamide, an active analogue of cyclophosphamide. Overexpression of the ALDH1 gene resulted in a significant increases in cyclophosphamide resistance in transduced L1210 and U937 cells (50% inhibition concentration [IC50], approximately 13 mumol/L). The resistant phenotype was specifically caused by ALDH1 overexpression as shown by its reversion by disulfiram, a specific ALDH1 inhibitor. ALDH1 transduction into peripheral blood human hematopoietic progenitor cells also led to significant increases (4- to 10-fold; IC50, approximately 3 to 4 mumol/L) in cyclophosphamide resistance in an in vitro colony-forming assay. These findings indicate that ALDH1 overexpression is sufficient to induce cyclophosphamide resistance in vitro and provide a basis for testing the efficacy of ALDH1 gene transduction to protect bone marrow cells from high-dose cyclophosphamide in vivo.

Leukaemoid reaction with megakaryocytic features in newborns with Down's syndrome.

A leukaemoid reaction was observed in 3 newborns with Down's syndrome. Thrombocytopenia was present in 2, requiring platelets transfusions in 1, and red cell transfusions were necessary in 2 patients. Blast cells characterization by specific monoclonal antibodies showed a prevalence of megakaryoblasts in all 3 cases. This feature was confirmed in 2 of them by the demonstration of platelet peroxidase (PPO) activity under transmission electron microscopy (TEM). A spontaneous remission of the leukaemoid picture was observed after 2-3 months. However, in 1 case a relapse of the myeloproliferative disorder with the same features of the blast cell population was diagnosed after 16 months. Chemotherapy with low-dose Ara-C, started because of a relevant clinical involvement, induced a complete remission.

Growth of normal versus leukemic bone marrow cells in long term culture from acute lymphoblastic and myeloblastic leukemias.

The ability of the in vitro long-term bone marrow culture (LTBMC) system to impair the survival of leukemic cells and to enhance the growth of normal progenitors has been studied. Bone marrow cells from 19 acute lymphoblastic leukemia (ALL) and 30 acute myeloid leukemia (AML) patients at diagnosis were grown in LTBMC for 4-10 weeks. In half of the cases the leukemic population declined down to undetectable levels and was replaced by putative normal hemopoietic precursors, both in ALL and in AML. In the remaining cases, leukemic cells persisted throughout the culture time and few if any normal hemopoietic cells were detected. These data led us to extend to the lymphoid compartment the previous observation of decreasing leukemic myeloid blasts in LTBMC. The potential of such cultures as an in vitro purging system for autologous bone marrow transplantation in selected poor-prognosis lymphoid malignancies should be explored, as has been done for acute and chronic myeloid leukemias.

Expression of integrins in human bone marrow.

Expression of integrins, a superfamily of glycoprotein alpha/beta heterodimers which integrate the cytoskeleton with the extracellular matrix and/or mediate cell-cell adhesive interactions, was examined on normal and leukaemic bone marrow cells by immunohistochemistry and immunotransmission electron microscopy (immuno-TEM). Among the beta 1/VLA molecules studied, VLA-2 and 6 were expressed on megakaryocytes and platelets, while VLA-4 was present on 40% of haemopoietic cells, including monocytes, erythroblasts and immature cells; this molecule was typically localized at sites of intercellular contact, as seen by immuno-TEM, suggesting it may be involved in interactions among haemopoietic cells during differentiation. In human long-term bone marrow cultures (LTBMC), VLA-1 and 3 were present respectively on 35% and 40% of the adherent cells which included fibroblasts and endothelial cells, as shown by double-labelling experiments; VLA-2 was expressed only on a subpopulation of fibroblasts. beta 2/LeuCAM molecules were absent from platelets, megakaryocytes and HLA-DR+/myeloperoxidase- early myeloid precursors, and appeared progressively during maturation in both lymphoid and myeloid cells. Expression of beta 3/cytoadhesin molecules was restricted to megakaryocytes and platelets and, in the adherent layer of LTBMC, to endothelial cells. The regulated expression and specific localization of integrins in the bone marrow suggest that these molecules may have a role in normal haemopoiesis.

Neuroblastoma during acute lymphoblastic leukemia in remission.

Neuroblastoma was diagnosed in a child after a 20-month remission of a pre-B acute lymphoblastic leukemia (ALL). Clumps of atypical cells suggestive of neuroblastoma were seen in the bone marrow. They were positive for monoclonal antibody (MoAb) UJ13A (neuroblastoma cells) and negative for MoAb T29/33 (anti-leucocyte common antigen CD45) with immunocytochemical staining. A right paravertebral mass displacing the kidney was demonstrated by abdominal echotomography, and serum vanilmandelic acid was slightly increased. Despite specific chemotherapy against neuroblastoma and after a transient clinical improvement, the patient died 7 months later of disseminated disease. Immunocytochemical staining on cells frozen at diagnosis of leukemia with MoAb UJ13A and T29/33 was unable to demonstrate neuroblastoma cells and showed the pattern usually observed in leukemia (UJ13A- and T29/33+).

Recombinant human interleukin-3 and recombinant human granulocyte-macrophage colony-stimulating factor administered in vivo after high-dose cyclophosphamide cancer chemotherapy: effect on hematopoiesis and microenvironment in human bone marrow.

The effects on bone marrow (BM) cell proliferation and differentiation of recombinant human interleukin-3 (rhIL-3) and recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) administered after high-dose (7 g/m2/d) cyclophosphamide (HD-CTX) chemotherapy were studied in nine patients with malignancies without BM involvement and in three control patients. rhIL-3 at a dose of 1 to 5 micrograms/kg/day was administered for 14 to 18 days by continuous intravenous (i.v.) infusion and rhGM-CSF was administered at a dose of 5.5 micrograms/kg/day for 14 days. Changes induced by cytokine treatment were assessed by morphoimmunohistochemical analysis of BM biopsies. Comparison was made in the cytokine-treated groups and with control patients who received HD-CTX alone. BM cellularity and the myeloid/erythroid (ME) ratio were lower in rhIL-3-treated than in rhGM-CSF-treated patients, but in both groups it was significantly higher than in the controls. The proportion of BM cells stained by PC10, a monoclonal antibody (MoAb) recognizing a proliferation-associated nuclear protein (PCNA), increased from 6.78% to 21.18% (P less than .02) after rhIL-3, and from 5% to 35.33% (P less than .001) after rhGM-CSF; no increase was observed in the control group. The frequency of CD34+ BM cells was unchanged after rhIL-3 (P = NS) and decreased after rhGM-CSF (P less than .001). In both groups, most of the PC10+ cells were represented by promyelocytes and myelocytes with no increase in blast cell numbers. rhIL-3-treated BM showed an increased number of megakaryocytes and increased proliferative activity of erythroid cells as compared with rhGM-CSF cases. BM stroma changes observed in both treated groups included endothelial cell proliferation, increased BM macrophage concentration, and increase in BM fibroblasts as detected with an anti-nerve growth factor receptor antibody. In most rhIL-3-treated cases, BM fibrosis developed after treatment. The same effect was not observed in rhGM-CSF patients.

Effects of recombinant human granulocyte colony-stimulating factor (CSF), human granulocyte macrophage-CSF, and gibbon interleukin-3 on hematopoiesis in human long-term bone marrow culture.

We have studied the effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF), hG macrophage-CSF (hGM-CSF), and gibbon interleukin-3 (gIL-3) on cell proliferation and differentiation in human long-term bone marrow culture (LTBMC). hG-CSF induced a maximal increase of 2.3-fold in both total nonadherent cells and GM cluster-forming cells, but only an increase of 1.7-fold in GM-colony-forming cell (GM-CFC) numbers, influencing mainly neutrophil differentiation. Cultures treated with hGM-CSF demonstrated a peak of 12.8-, 21- and 3.2-fold elevations in total nonadherent cells, cluster, and GM-CFC, respectively, and influenced differentiation of neutrophils, monocytes, eosinophils, and lymphocytes. Cultures treated with gIL-3 demonstrated the largest expansion in the GM-CFC population, reaching a maximum of 5.3-fold in relation to that of unstimulated controls. IL-3 treatment also increased the numbers of GM clusters and mature cells (including all myeloid cells and lymphocytes) 7.8- and 4.8-fold, respectively. Similar quantitative and qualitative changes were induced by G-CSF, GM-CSF, and IL-3 in LTBMCs of patients in remission after treatment for acute lymphoblastic leukemia or Hodgkin's lymphoma. Overall, the expansion of GM progenitor cells in cultures treated with growth factors was larger in the adherent cell layer than in the nonadherent cell fraction. In addition, hGM-CSF, gIL-3, and hG-CSF to a less extent, increased the cycling rates of GM-CFC progenitors located in the adherent layer. These results indicate that hG-CSF is a much less potent stimulus of hematopoiesis in LTBMC than the other CSFs assayed, and that the increases in cell production after treatment with G-CSF, GM-CSF, or IL-3 may be achieved by primary expansion of different cell populations within the hierarchy of the hematopoietic system. The effects of the growth factors were transient and the longevity of hematopoiesis in the cultures was not altered, suggesting that treatment with IL-3, GM-CSF, or G-CSF had not compromised the ability of primitive cells to give rise to mature cells. This indicates that the stromal microenvironment in LTBMC can override potential differentiation-inducing activities of the CSFs.

Biological and clinical features of B-precursor childhood acute lymphoblastic leukemia showing CD2 and/or E-rosette co-expression.

BACKGROUND: Co-expression of the T-associated marker CD2 or E-rosette in non-T acute leukemia has rarely been reported. In this paper the incidence of such co-expression, together with its biologic features and clinical relevance, was evaluated in a large series of childhood "common" acute lymphoblastic leukemia (cALL) cases. METHODS: This analysis was performed retrospectively on 306 cases of childhood non-T ALL. CD2 and/or E-rosette co-expression with other non-T markers was usually shown by a clear overlap between the percentages of T and non-T markers, by the great difference between positivity for CD2 or E-rosette and other T markers, and by double staining for CD2 and CD10 in one case. Two cases were further studied by a panel of nine different CD2 monoclonal antibodies (MAbs) representative of different epitopes. DNA analysis for the configuration of Ig and TCR genes (beta, gamma, and delta locus) was carried out in three cases. RESULTS: Eleven out of 306 cases (3.6%) showed CD2 and/or E-rosette co-expression in otherwise typical cALL. Data obtained in two cases with the use of nine different CD2 Mabs showed a different pattern of reactivity between leukemic B cells and normal T cells. The configuration of Ig and TCR genes was compatible with B-lineage ALL. CONCLUSIONS: CD2 and/or E-rosette co-expression was observed in a small subset of acute leukemias showing immunophenotypic and genotypic features of B-lineage ALL. A pattern of reactivity different from that seen in normal T cells was observed in the two cases tested with a large panel of CD2 MAbs. No association was found with other known prognostic factors, and 8 of these 11 patients have been in first continuous remission for 36-93 months.

Functional glucocorticoid receptor modulates pancreatic carcinoma growth through an autocrine loop.

Several peptide hormones have been shown to influence growth and function in pancreatic carcinoma and have given evidence for an autocrine feedback loop governing the proliferation of these malignant cells. Conversely, steroid hormones including glucocorticoids have been shown to inhibit the growth of pancreatic cancer cells; however, the prevalence of the glucocorticoid receptor or its mechanism of growth suppression in these tumors is unknown. The ability of growth factors thought to be active in this autocrine loop to reverse the glucocorticoid-induced growth inhibition was studied in vitro in a human pancreatic adenocarcinoma (HPAC) cell line with a well-characterized glucocorticoid receptor (GR). The glucocorticoid dexamethasone (DEX) inhibited growth in a dose-dependent manner as measured by a [3H]thymidine incorporation assay as well as an MTT cell proliferation assay. Maximal effects were seen within 48 hr at a concentration of 100 nM DEX, suppressing growth to approximately 18% of control. When the maximally suppressed DEX-treated cells were exposed to exogenous growth factors, they rapidly attained or exceeded the growth rate of control cells: insulin-like growth factor = 106%, transforming growth factor-alpha = 134%, insulin = 151%, and epidermal growth factor = 187% (all P < 0.05, Student's t test). In order to determine the frequency of the GR in pancreatic cancer and the clinical relevance of our findings, immunohistochemical staining for the GR was performed on 20 human tumors. Twelve (60%) of all cancers, as well as all normal pancreatic tissues (n = 4), stained positively for cytoplasmic and/or nuclear GR with expression correlating highly with degree of tumor differentiation (Kruskal-Wallis test, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Constitutive expression of GATA-1, EPOR, alpha-globin, and gamma-globin genes in myeloid clonogenic cells from juvenile chronic myelocytic leukemia.

Juvenile chronic myelocytic leukemia (JCML) is a rare disorder of early childhood. Characteristic of JCML are the progressive appearance of high levels of fetal hemoglobin (HbF), reflecting a true reversion to a fetal type of erythropoiesis, and the presence of colony-forming cells able to grow in vitro spontaneously in the absence of growth factors. To better understand the relationship between the erythroid abnormalities and the leukemic process, we analyzed the expression pattern of specific genes related to erythroid differentiation--GATA-1, EPOR, alpha-globin, beta-globin, and gamma-globin genes--in JCML peripheral blood (PB) cells and in vitro-derived colonies. Northern blot analysis of PB cells from five JCML patients indicated levels of GATA-1 transcripts much higher than those usually found in other types of leukemic cells, and S1 nuclease protection assay detected significantly increased expression of gamma-globin mRNA. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of single granulocyte-macrophage colony-forming unit (CFU-GM) colonies, obtained in vitro in the absence of added growth factors from four JCML patients, detected GATA-1, EPOR, and globin (alpha and gamma) transcripts in most of the colonies tested, in contrast with control CFU-GM from normal bone marrow, which were positive only for GATA-1. Single JCML colonies were tested for the presence of two different transcripts; whereas alpha- and gamma-globin genes appeared mostly coexpressed, beta-globin mRNA was detected only in a minority of the gamma-globin-positive colonies, indicating that the leukemic pattern of hemoglobin synthesis is mainly fetal. In addition, the leukemic cells occurring during blast crisis of one of our patients displayed the typical features of a stem cell leukemia (CD34+, CD19-, CD2-, myeloperoxidase-). In this sorted CD34+ population, we detected the presence of a marker chromosome, der(12)t(3;12), previously identified in bone marrow cells at diagnosis and an expression pattern superimposable to that of the JCML colonies, consistently displaying a high gamma-globin:beta-globin mRNA ratio. The expression of erythroid markers within populations of leukemic cells, both in vivo and in vitro, supports the hypothesis that abnormal JCML erythroid cells may originate from the same mutated progenitor that sustains the growth of the leukemic cells.

Stromal cells in haemopoiesis.

Stromal cells of the bone marrow can provide the growth-promoting and differentiation-inducing molecules which are necessary for haemopoiesis. While the nature of these stimuli is largely unknown, the development of haemopoietic cells in association with stromal cells requires intimate cell contact. Molecules of the extracellular matrix, such as heparan sulphate, are able to bind growth factors and in this way the stromal cells may form microenvironmental niches which preferentially promote development of multipotent and committed cells along discrete lineages. Cells from some patients with acute and chronic myeloid and lymphoid leukaemias are defective in their ability to interact with stromal cells and consequently cannot survive in stromal cell-mediated long-term marrow cultures. We have exploited this phenomenon to obtain normal haemopoietic cells from patients with leukaemia, and to use these cells for successful autografting in patients with acute and chronic myeloid leukaemias.

Juvenile chronic myelogenous leukemia: report of the Italian Registry. Associazione Italiana di Ematologia Oncologia Pediatrica (AIEOP).

BACKGROUND: Since juvenile chronic myeloid leukemia (JCML) represents no more than 2% of leukemia in children, clinical and investigative experience of this disorder has been limited. In order to evaluate the diagnostic criteria currently applied, to provide centralized facilities for blood culture and to collect data on treatment, and to propose a uniform treatment protocol in our country, a National Registry for JCML was recently established in the "Associazione Italiana di Ematologia Oncologia Pediatrica" (AIEOP). PATIENTS: Out of the 24 cases reported from 9/35 centres, 22 were considered sufficiently documented and were enrolled in the Registry. Clonogenic assay on marrow and peripheral blood cells was performed in all available cases. RESULTS: Common features were non-specific clinical (fever, splenomegaly, hepatomegaly, lymphadenomegaly) and hematologic alterations (anemia, thrombocytopenia, leukocytosis usually < 50 x 10(9)/l, monocytosis, circulating immature granulocytes, increased HbF, normal karyotype). In 11 out of 11 cases, in vitro blood cultures showed the spontaneous growth of CFU-C in the absence of any exogenous source of colony-stimulating activity. Twelve of the 22 patients (55%) are alive (probability of survival 47.7%); most patients were treated according to an acute myeloid leukemia-directed schedule; 5/7 children treated with interferon were alive with disease after a median time of 29 months from diagnosis (range 8-95 months); 4/5 children who underwent bone marrow transplantation were alive in complete remission 10, 24, 42 and 118 months, after the diagnosis. Age < 1 year at presentation was the most significant prognostic factor in terms of probability of survival (80% vs 28%; p = 0.0024). CONCLUSIONS: JCML must be considered in young children for whom acute leukemia has been suspected but ruled out; in vitro cultures should be considered mandatory to confirm the diagnosis. Age less than one year at the presentation was associated with prolonged survival. Only bone marrow transplantation was followed by prolonged disease-free survival, whereas intensive chemotherapy seemed not very effective and potentially associated with life-threatening complications. Interferon therapy appears to be a promising alternative to chemotherapy while the value of unrelated marrow donor is explored.