Biomedical subjects

G Visani

Publications and source records attributed to G Visani.

At least 109 records · Page 6Linked to original sources

PubMed1995

All-trans retinoic acid shows multiple effects on the survival, proliferation and differentiation of human fetal CD34+ haemopoietic progenitor cells.

To evaluate the effect of all-trans retinoic acid (RA) on fetal haemopoiesis, we performed serum-free liquid and semisolid cultures using CD34+ cells purified from midtrimester human fetal blood samples. RA, at both physiological (10(-11) and 10(-12)M) and pharmacological (10(-6) and 10(-7)M) concentrations, significantly (P < 0.01) promoted the survival of fetal CD34+ cells in liquid cultures from day 3 onwards, by suppressing apoptosis induced by serum and growth factor deprivation. On the other hand, RA alone had no significant effect on the proliferation and differentiation of fetal haemopoietic progenitors. In the presence of optimal concentrations of recombinant interleukin-3 (IL-3), stem cell factor (SCF), granulocyte/macrophage-colony stimulating factor (GM-CSF), and erythropoietin (Epo), low and high doses of RA induced striking differential effects on CD34+ cell proliferation in liquid cultures and colony formation in semisolid assays. In fact, 10(-11)M and 10(-12)M RA were able to: (i) significantly (P < 0.05) increase 3H-thymidine uptake by fetal CD34+ cells in liquid cultures, and (ii) variably promote the growth of pluripotent (CFU-GEMM, P < 0.05), early (BFU-meg) and late (CFU-meg, P < 0.01) megakaryocyte, granulocyte/macrophage (CFU-GM, P < 0.01) and erythroid (BFU-E) progenitors in semisolid cultures. On the contrary, 10(-6) and 10(-7)M RA induced: (i) an overall inhibition (P < 0.01) of CD34+ cell growth in liquid cultures; (ii) a marked suppression of BFU-E colony formation (P < 0.01) at all Epo concentrations examined (0.002-4 IU/ml); and (iii) a significant (P < 0.01) stimulation of CFU-GM with a shift from mixed granulocyte/macrophage to pure granulocyte colonies, whereas it had little effect on the growth of CFU-GEMM, BFU-meg and CFU-meg. Our data, as a whole, demonstrate that RA has direct complex effects on the survival, growth and clonal expansion of fetal haemopoietic progenitor cells, mainly depending on the presence of recombinant cytokines, the type of progenitor and the concentrations of RA.

Cell Differentiation↗

PubMed1995

Molecular analysis of PML-RAR alpha fusion mRNA detected by reverse transcription-polymerase chain reaction assay in long-term disease-free acute promyelocytic leukaemia patients.

By use of RT-PCR of PML/RAR alpha, we evaluated bone marrow aspirates in 10 patients with APL in long-term disease-free status after induction chemotherapy and consolidation (median 54 months: range 33-101 months from complete remission). All patients were in clinical and cytogenetic remission at the time of molecular evaluation (range 32-96 months from CR). All patients but one were found to be RT-PCR negative at the molecular level for the expression of PML-RAR alpha transcript, confirming that the majority of the patients with long-term survival of APL are characterized by the eradication of the neoplastic clone.

Bone Marrow↗

PubMed1995

Interleukin-11 (IL-11) acts as a synergistic factor for the proliferation of human myeloid leukaemic cells.

Interleukin-11 is a stromal cells derived cytokine which stimulates the proliferation of primitive haemopoietic progenitor cells. For this paper we have studied the constitutive expression of IL-11 mRNA in a panel of wellknown leukaemic cell lines and samples from AML patients at diagnosis. Moreover, the same cellular populations were evaluated for their proliferative response to recombinant-human-(r-hu). IL-11 alone and combined with r-hu-IL-3, granulocyte-macrophage colony stimulating factor (GM-CSF) and stem cell factor (SCF, c-kit ligand). The colony-forming ability of HL60, K562, KG1 cells and eight fresh AML cell populations was assessed by a clonogenic assay in methylcellulose. In eight additional AML cases the number of S-phase leukaemic cells induced by IL-11 was determined by the bromodeoxyuridine (BRDU) incorporation assay after 3d of liquid culture. IL-11, as single cytokine, did not stimulate the colony formation of the three myeloid cell lines under serum-containing and serum-free conditions. In contrast, the proliferation of the leukaemic cells in response to IL-3, GM-CSF and SCF was enhanced by co-incubation with IL-11, and this effect was reversed in blocking experiments by the anti-IL-11 Moab. When tested on primary AML samples, IL-11 alone showed little, if any, proliferative activity. However, it increased the IL-3-dependent blast colony formation in eight out of eight cases and GM-CSF in seven cases. IL-11 also augmented synergistically the number of CFU-L stimulated by SCF in seven cases. A combination of three factors (IL-11, SCF and IL-3) yielded optimal colony formation. The BRDU studies showed the significant increase of AML cells in S-phase when IL-11 was combined with SCF, whereas the two CSF had no activity on their own. Positive interaction was also observed when IL-11 was added to IL-3 supplemented cultures in five out of eight cases tested. Reverse transcriptase-polymerase chain reaction amplification (RT-PCR) demonstrated the constitutive expression of IL-11 mRNA in all the cell lines and 11/12 AML samples studied at diagnosis. These results indicate that IL-11 is expressed in leukaemic myeloid cells and that their proliferation is regulated by the cytokine which acts as a synergistic factor.

Adolescent↗

PubMed1995

Factor VIII inhibitor prior to and during secondary acute nonlymphocytic leukemia in a patient with cured Hodgkin's disease.

We report a 54-year-old patient with Hodgkin's disease who achieved a complete remission after combined modality treatment. Three years later the patient developed a severe hemorrhagic syndrome, concomitant with the onset of a factor VIII inhibitor in plasma. The control of very proteiform bleedings was extremely difficult, even with plasmaphereses, as well as with immunosuppressive and substitutive therapies. Two years later, a secondary acute nonlymphocytic leukemia (ANLL) was diagnosed. Two courses of chemotherapy with fludarabine, cytosine arabinoside and G-CSF (FLAG) were able to obtain a complete remission. Hemorrhagic complications were mainly linked to thrombocytopenia and continued until recovery of thrombopoiesis. Factor VIII inhibitor levels and related clinical symptoms decreased progressively. In conclusion, we suggest that FLAG succeeded in inhibiting an abnormal lymphoid clone responsible for factor VIII inhibitor production, suggesting a possible role for intensive chemotherapy in similar situations, which are often refractory to conventional immunosuppressive and depletive therapy.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1995

G-CSF in the biology and treatment of acute myeloid leukemias.

Granulocyte colony-stimulating factor (G-CSF) is an hemopoietic growth factor produced by fibroblasts, monocytes and endothelial cells. The role of G-CSF in the biology of acute myeloid leukemia (AML) has been investigated by several authors, who have demonstrated receptor mediated enhanced proliferation of AML blasts in vitro, in the presence of G-CSF. This effect is further increased by addition of other cytokines such as GM-CSF, IL3, IL4, Stem cell factor (SCF), while Tumor Necrosis Factor (TNF) and Transforming Growth Factor beta 1 (TGF beta 1) seem to exert an inhibitory activity. An autocrine production of G-CSF by AML cells, a paracrine production by accessory cells and a protective effect displayed by G-CSF against programmed cell death could partially contribute to explain the pathogenesis of AML. In vivo, G-CSF has been used after chemotherapy in AML, in order to improve hemopoietic recovery in patients at high risk of infection. Current studies are focusing on better definition of the role of G-CSF, as such or combined with other biological modifiers, in dose intensification and autologous bone marrow or peripheral blood stem cell transplantation.

Clinical Trials as Topic↗

PubMed1995

All-trans retinoic acid in the treatment of myelodysplastic syndromes.

Myelodysplastic syndromes (MDS) are a group of hematopoietic disorders characterized by uni- or multilineage maturation defects of the bone marrow. Controversial therapeutic results have been obtained using growth factors or differentiating agents such as 13-cis retinoic acid. In this pilot study we evaluated the effects of all-trans retinoic acid (ATRA) in 10 MDS patients (5 male, 5 female). Six patients had refractory anemia (RA), 1 had refractory anemia with excess of blasts (RAEB), and 3 had refractory anemia with excess of blasts in transformation (RAEB-t). All patients received the same dose of ATRA (45 mg/sqm/day) orally for 6 weeks. A rise in hemoglobin concentration > 1g/dl was observed in 3/10 patients, while 5/10 patients showed an increase in granulocyte count > 0.5 x 10(9)/l without concomitant increase in the percentage of blast cells in the bone marrow. A rise in the platelet count > 50 x 10(9)/l was observed in 1/10 patients. All the effects were transient and maximal responses were obtained by the fourth week of treatment. Thereafter, the peripheral blood counts started to drop again, reaching pre-therapy values by the end of the treatment. This phenomenon could be attributed either to the exhaustion of an ATRA-responding cell pool, the development of cellular resistance to ATRA or to a reduction of plasma ATRA levels after prolonged treatment. According to our results, it seems that ATRA might have therapeutic efficacy in MDS, particularly if its effect could be improved by combinations with other differentiating agents or growth factors.

Adult↗

PubMed1995

MEC (mitoxantrone, etoposide and intermediate dose cytarabine): an effective induction regimen for previously untreated acute non-lymphocytic leukemia.

Twenty-three patients with acute non lymphocytic leukemia (ANLL), were treated with a single-6 day course of Mitoxantrone 6mg/m2/day, Etoposide 80mg/m2/day and intermediate dose Cytarabine (ara-C) 1g/m2/day (MEC). Patients who achieved complete remission (CR) were submitted to a 4-day-course of MEC as consolidation. Seventeen patients (73.9%) obtained CR, five patients (22.7%) were resistant to the treatment and one patient died during induction. Median remission duration was 11 months; overall median survival was 16 months. Relapses occurred in 11 patients; eight patients are still alive: 6 in 1st, 2 in 2nd CR (mean survival 20.1 months, range 17-26). All patients experienced severe myelosuppression comparable to that observed after classical induction cycles including ara-C in continuous intravenous infusion; none, however, died of infection. Non-hematologic toxicity was minimal; in particular, neurotoxicity was not observed. According to our results, the MEC regimen, which was previously demonstrated to be active in refractory patients, represents an effective induction treatment in ANLL, with an acceptable toxicity.

Adult↗

PubMed1994

A subset of human CD34+ hematopoietic progenitors express low levels of CD4, the high-affinity receptor for human immunodeficiency virus-type 1.

We investigated the expression of CD4 antigen in normal bone marrow (BM) samples, enriched in CD34+ hematopoietic progenitor cells. At flow cytometry, a significant fraction (ranging from 25% to 65%) of CD34+ cells also showed low levels of CD4 antigen on their surface. The CD4 receptor densities on the surface of hematopoietic progenitors was approximately 50% that of peripheral blood monocytes and 5% of peripheral blood T lymphocytes. In immunoprecipitation experiments, the CD4 antigen expressed by BM hematopoietic progenitors appeared to be the same form expressed by mature peripheral blood CD4+ cells and appeared to be a potentially functional receptor for human immunodeficiency virus-type 1, because it specifically bound recombinant envelope gp120. Moreover, BM samples, highly enriched in CD34+ cells, showed the presence of CD4 mRNA at reverse transcription-polymerase chain reaction examination. In experiments of complement-mediated cytotoxicity with Leu3-a+Leu3b anti-CD4 monoclonal antibody, a significant reduction in the number of both classes of megakaryocyte (burst-forming unit-meg [BFU-meg] and colony-forming unit-meg [CFU-meg]) and granulocyte/macrophage (CFU-GM) progenitors was observed, whereas erythroid (BFU-E) progenitors were only slightly affected. Moreover, purified CD4+ BM cells obtained by immunomagnetic selection, using high concentrations of Leu3a+Leu3b, showed a colony-forming ability of megakaryocyte and granulocyte/macrophage progenitors comparable with that of CD4- BM cells. In conclusion, the present data show that immature hematopoietic progenitor cells express low levels of CD4, the high-affinity receptor of human immunodeficiency virus-type 1.

Antibodies, Monoclonal↗

PubMed1994

Hair dye use and other risk factors for leukemia and pre-leukemia: a case-control study. Italian Leukemia Study Group.

A case-control study was carried out to examine the relation of three subtypes of leukemia cells and refractory anemia with excess of blasts to selected behavioral and environmental factors. Cases aged 15 years or older were recruited in three hospitals located in Rome, Bologna, and Pavia, respectively. Outpatients who were either normal or had nonneoplastic hematologic disorders and were seen in the same hospitals as the cases were enrolled as controls. Two hundred fifty-two patients with acute myeloid leukemia, 100 with acute lymphocytic leukemia, 111 with refractory anemia with excess of blasts, 156 with chronic myeloid leukemia, and 1,161 controls were included in the study. Refractory anemia with excess of blasts and chronic myeloid leukemia were included because they are regarded as forms of pre-leukemia. Odds ratio estimates were generally imprecise, but associations were suggested between specific case subtypes and exposure to dark hair dye, selected occupations (shoemaker, painter, electrician, child care), residence in houses built with tuff, and smoking. Although the exploratory nature of the study and its limited statistical power preclude firm conclusions, its results are consistent with those of previous studies, and are in general biologically plausible.

Adolescent↗

PubMed1994

In vitro exposure to human immunodeficiency virus type 1 induces apoptotic cell death of the factor-dependent TF-1 hematopoietic cell line.

In this study, we evaluated the effect of a short-term exposure (2 hours) to two different lymphocytotropic strains of human immunodeficiency virus type 1 (HIV-1; HIVIIIB and ICR-3) on the survival of a factor-dependent CD34+ hematopoietic progenitor cell line (TF-1). At flow cytometry analysis, a significant (P < .05) increase in the frequency of apoptotic cell death was observed in HIV-1-treated TF-1 cells, supplemented with low doses of either interleukin-3 (IL-3; 0.02 to 1 ng/mL) or granulocyte-macrophage colony-stimulating factor (GM-CSF; 0.02 to 0.2 ng/mL) with respect to mock-treated cells. On the other hand, higher doses of both cytokines or combinations of suboptimal concentrations of IL-3 plus GM-CSF (eg, 0.2, plus 0.2 ng/mL) completely reversed the HIV-1-induced increase of apoptosis. Remarkably, no signs of productive or latent virus replication were ever observed in HIV-1-treated TF-1 cells up to 16 days of liquid culture. In parallel experiments, the in vitro exposure to HIVIIIB induced a significant and progressive increase of apoptotic death in purified bone marrow CD34+ cells, seeded in liquid cultures in the presence of 1 ng/mL IL-3. The HIV-1-induced apoptosis of TF-1 cells was likely triggered by the simple interaction of HIV-1 envelope glycoprotein gp120 with CD4 receptor, which was expressed at a low level on the surface of TF-1 cells. In fact, treatment of TF-1 cells with recombinant gp120 plus a polyclonal anti-gp120 antibody or with anti-CD4 monoclonal antibody plus rabbit antimouse IgG significantly increased the percentage of apoptotic death. These data suggest that HIV-1, and perhaps also free gp120 in the presence of anti-gp120 antibody; could play a direct role in the pathogenesis of peripheral blood cytopenias in acquired immunodeficiency syndrome patients by inducing apoptotic death of hematopoietic progenitor cells without the need of a direct infection.

Antigens, CD↗

PubMed1994

Apoptosis induction with three nucleoside analogs on freshly isolated B-chronic lymphocytic leukemia cells.

The cytotoxic effects and the induction of programmed cell death (apoptosis) by Fludarabine (FLU), 2-chlorodeoxyadenosine (2-CdA), and deoxycoformycin (DCF) with/without alpha-interferon (alpha-IFN) were evaluated in vitro against freshly isolated B-chronic lymphocytic leukemia (B-CLL) cells. Cytotoxicity was evaluated according to the soluble tetrazolium/formazan assay. Regarding the cytotoxicity, FLU, 2-CdA, and DCF showed a mean antitumor activity of 45% +/- 3.39 (mean +/- S.D.), 55% +/- 4.72, and 20% +/- 3.16, respectively. alpha-IFN alone showed a mean cytotoxic activity of 10% +/- 2.72. The cytotoxicity of these purine analogues in combination with alpha-IFN was 52% +/- 2.97, 75% +/- 3.41, and 26% +/- 7.09, respectively. We observed a statistically significant increase of cytotoxicity compared to controls in FLU alone (P < 0.05), 2-CdA (P < 0.05), and their combination with alpha-IFN (P < 0.05). Apoptosis was evaluated by electrophoresis gel of DNA oligonucleosomal fragments and by a cytofluorimetric method. Only FLU and 2-CdA activated the apoptosis and DCF showed a minor apoptotic pathway amount. These apoptosis data were confirmed by both gel electrophoresis of DNA and by propidium iodide cytofluorimetric method. FLU and 2-CdA show activity in B-CLL cells by direct cytotoxic action and the induction of cell death by apoptosis; in the future, it would be interesting to utilize these in vitro assays in monitoring chemosensitivity and predicting response for the clinical use.

Aged↗

PubMed1994

FLAG (fludarabine+cytosine arabinoside+G-CSF) induces complete remission in acute-phase chronic myeloid leukaemia: a case report.

The adenine nucleoside analogue fludarabine phosphate in combination with cytosine-arabinoside (Ara-C) and granulocyte-colony stimulating factor (G-CSF) has recently proved effective in the treatment of poor-prognosis acute non-lymphoid leukaemia. We used this triple combination in a case of Ph1+ chronic myeloid leukaemia (CML) unresponsive to alpha interferon that had progressed to acute phase after 5 months of treatment with 6-mercaptopurine plus hydroxyurea. The patient was treated with four courses of fludarabine 30 mg/m2 + Ara-C 2 g/m2 (days 1-5) and G-CSF (from day 0 to polymorphonuclear (PMN) recovery). Bone marrow blasts decreased from 80% to less than 5%, and karyotyping showed a progressive clearance of Ph1+ metaphases (from 100% to 9% after the fourth course). The patient is presently receiving autologous bone marrow transplantation (ABMT). This therapeutic success in a patient for whom conventional treatment would usually be ineffective makes this combination worthy of further studies, in view of its wider use as a preparative regimen to ABMT in CML.

Adult↗

PubMed1994

In vitro growth of human fetal CD34+ cells in the presence of various combinations of recombinant cytokines under serum-free culture conditions.

CD34+ cells were purified from midtrimester human fetal blood and adult bone marrow samples and seeded in serum-free fibrin-clot cultures in order to evaluate the number and the responsiveness to recombinant cytokines of pluripotent (CFU-GEMM), erythroid (BFU-E), megakaryocyte (BFU-meg and CFU-meg) and granulocyte/macrophage (CFU-GM) haemopoietic progenitor cells. The number of the different haemopoietic progenitors/1 x 10(3) CD34+ cells, except CFU-meg, was significantly higher in fetal blood than in adult bone marrow in cultures stimulated by any combination of cytokines including interleukin-3 (IL-3), granulocyte/macrophage colony stimulating factor (GM-CSF) or stem cell factor (SCF) plus erythropoietin (Epo). Nevertheless, whereas adult BFU-E showed a maximal growth in the presence of Epo plus IL-3 or Epo plus SCF, fetal BFU-E showed an optimal growth in the presence of Epo alone, the sensitivity of fetal BFU-E to suboptimal concentrations of Epo being approximately 10-15-fold higher than that of adult BFU-E. Addition of optimal concentrations of IL-3, GM-CSF or SCF, alone or in various combinations, to Epo-containing cultures induced a significant increase in both the number and size of fetal CFU-GEMM, and CFU-GM, and a parallel decrease of fetal BFU-E. Finally, SCF potently synergized with IL-3 in increasing the growth of both classes of fetal megakaryocyte progenitors, BFU-meg and CFU-meg.

Adult↗

PubMed1994

Increased expression of myeloid antigen markers in adult acute lymphoblastic leukaemia patients: diagnostic and prognostic implications.

By applying direct immunofluorescence with a dual-staining technique we were able to demonstrate that 20/37 (54%) patients with acute lymphoblastic leukemia (ALL) expressed both lymphoid and myeloid antigens on the same leukaemic cells. CD13 and CD33 myeloid antigens were detected in 18/20 and in 15/20 cases respectively, and both in 13. Molecular studies confirmed that the four patients with T-cell phenotype had molecular rearrangement of T-cell receptor (TcR) beta chain, and 26 ALL patients with 'B-cell' phenotype showed JH rearrangement. Two ALL patients without (ALL/My-) and three with myeloid antigens (ALL/My+) also demonstrated bcr/abl rearrangement. Both groups of patients had similar presenting features such as age, sex, Hb level, white blood cells, platelet counts and cytogenetic features. Complete response was achieved in 16/17 (94%) ALL/My- patients and in 15/18 (83%) ALL/My+ patients (two deaths occurred during induction) with a mean duration of 17 and 16 months respectively and with similar survival and event-free survival curves. Myeloid antigen expression in adult ALL patients may occur more frequently than previously reported. The presence of myeloid antigen does not identify, in our series, a higher-risk subgroup of patients, although lack of any statistical evidence of prognostic significance needs to be confirmed in a larger case study.

Adolescent↗

PubMed1994

Hydroxyurea enhances 3'-azido-3'-deoxythymidine (AZT) cytotoxicity in human chronic myeloid leukemia models.

In this report we have evaluated the cytotoxic activity of 3'-azido-3'-deoxythymidine (AZT) used in combination with hydroxyurea (HU), an agent which disrupts de novo thymidylate synthesis. In 2 chronic myeloid leukemia (CML) cell lines, K562 and RWLeu4, the IC50 of AZT was 8 mumol/l and 28 mumol/l respectively, after a 5-day exposure, and the IC50 of HU was 80 mumol/l and 70 mumol/l respectively. In the presence of various concentrations of HU (1 mumol/l-100 mumol/l) the IC50 of AZT in both cell lines was significantly reduced and subsequent isobologram analysis revealed synergistic activity. Similarly, analysis of [3H]AZT incorporation into the DNA fraction of these cells indicated that exposure to AZT+HU resulted in an increased incorporation of AZT into DNA when compared to incubation in AZT alone. Biochemically, this effect appeared to be related to a decrease in dTTP pools caused by HU. The combination AZT+HU has also been demonstrated to exert a synergistic effect in inhibiting colony growth of bone marrow granulocyte-macrophage progenitors (CFU-GM) from patients affected by Ph1+ CML in chronic phase. These results are promising in view of a possible in vivo utilization of this drug combination.

Bone Marrow↗

PubMed1994

All-trans retinoic acid and induction of apoptosis in acute promyelocytic leukemia cells.

All-trans retinoic acid (ATRA) represents a highly effective treatment for acute promyelocytic leukemia (M3-ANLL). This compound induces the leukemic promyelocytes to differentiate into morphologically and phenotypically mature myeloid cells. The mechanism of action of ATRA is far from fully understood. It has recently been reported that, along with its differentiation activity, ATRA causes apoptosis in the acute promyelocytic leukemia cell line HL-60. In this study we attempted to test whether ATRA is also able to induce apoptosis in fresh leukemic cells from M3-ANLL patients. Our results indicated that although morphological differentiation was detectable in 9/9 M3-ANLL samples after in vitro exposure to ATRA 10(-6) M, the percentage of apoptotic cells in the treated samples did not significantly differ from that obtained in controls (13.1% vs 9.4% respectively, after 8 days exposure). These data suggest that apoptosis does not seem to be the key mechanism by which ATRA exerts its action in M3-ANLL, at least at the blast cell level.

Apoptosis↗

PubMed1994

Induction of "in vitro" apoptosis by fludarabine in freshly isolated B-chronic lymphocytic leukemia cells.

The cytotoxic effects and apoptosis (programmed cell death) induced by fludarabine (FLU), interleukin-2 (IL-2), interleukin-4 (IL-4), IL-2 plus IL-4, alpha-interferon (alpha-IFN), and mafosfamide were evaluated "in vitro" on freshly isolated B-cell chronic lymphocytic leukemia (B-CLL) cells. Cytotoxicity was evaluated according to the soluble tetrazolium/formazan assay. Treatment with mafosfamide, fludarabine, and IL-4 resulted in significant anti-tumor activity against all the freshly isolated samples. On the other hand, no significant cytotoxic activity was observed with alpha-IFN, IL-2, and the combination of IL-2 and IL-4. Apoptosis was evaluated by electrophoresis gel of DNA oligonucleosomal fragments and only FLU significantly activated apoptosis in all the samples. It appears that fludarabine is active against B-CLL cells acting by an direct cytotoxic effect and/or the induction of cell death by apoptosis.

Antineoplastic Agents↗

PubMed1994

Pre-treatment with all-trans retinoic acid accelerates polymorphonuclear recovery after chemotherapy in patients with acute promyelocytic leukemia.

All-trans retinoic acid (ATRA) is currently being used as remission induction treatment for acute promyelocytic leukemia (APL). Conventional chemotherapy is added both during and after ATRA treatment, in order to avoid the occurrence of hyperleukocytosis, and to improve the duration of complete remission. In this study we analysed the hematopoietic recovery of 18 consecutive APL patients after standard Idarubicin or Daunorubicin +/- Cytosine-Arabinoside regimens. 9 of the patients were at the onset of the disease, (CHT group) while 9 had been pre-treated with ATRA 45 mg/sqm/day for at least 3 months (ATRA group). 500 PMN/mmc were reached after 20.8 day from the end of treatment in CHT group and after 12.0 days in ATRA group (p = 0.007). Platelets recovery was faster, even though not significantly in ATRA group. Interestingly, PMN recovery in ATRA group was even shorter (p = 0.004) than that obtained in CHT group, after the first course of chemotherapy (treatment in CR vs treatment in CR). If these results are confirmed in a larger study, a protective effect of ATRA on normal residual hemopoiesis should be postulated.

Adult↗