FLT3-targeted therapy restores GATA1 pathway function in NPM1/FLT3-ITD mutated acute myeloid leukaemia

One-third of newly diagnosed adult acute myeloid leukaemia (AML) carry FLT3 mutations, which frequently occur together with nucleophosmin (NPM1) mutations and are associated with worse prognosis. FLT3 inhibitors are widely used in clinics with limitations due to drug resistance. AML cells carrying FLT3 mutations in both mouse models and patients present low expression of GATA1, a gene involved in haematopoietic changes preceding AML. Here, we show that FLT3 inhibition induces cellular responses and restores the GATA1 pathway and functions in NPM1/FLT3-ITD mutated AML, thus providing a new mechanism of action for this drug.

A venetoclax and azacitidine bridge-to-transplant strategy for NPM1-mutated acute myeloid leukaemia in molecular failure

NPM1-mutated acute myeloid leukaemia (NPM1mut AML) represents a mostly favourable/intermediate risk disease that benefits from allogeneic haematopoietic stem cell transplantation (HSCT) in case of measurable residual disease (MRD) relapse or persistence after induction chemotherapy. Although the negative prognostic role of pre-HSCT MRD is established, no recommendations are available for the management of peri-transplant molecular failure (MF). Based on the efficacy data of venetoclax (VEN)-based treatment in NPM1mut AML older patients, we retrospectively analysed the off-label combination of VEN plus azacitidine (AZA) as bridge-to-transplant strategy in 11 NPM1mut MRD-positive fit AML patients. Patients were in MRD-positive complete remission (CRMRDpos ) at the time of treatment: nine in molecular relapse and two in molecular persistence. After a median number of two cycles (range 1-4) of VEN-AZA, 9/11 (81.8%) achieved CRMRD -negative (CRMRDneg ). All 11 patients proceeded to HSCT. With a median follow-up from treatment start of 26 months, and a median post-HSCT follow-up of 19 months, 10/11 patients are alive (1 died from non-relapse mortality), and 9/10 patients are in MRDneg status. This patient series highlights the efficacy and safety of VEN-AZA to prevent overt relapse, achieve deep responses and preserve patient fitness before HSCT, in patients with NPM1mut AML in MF.

Maesopsin 4-O-beta-D-glucoside, a natural compound isolated from the leaves of Artocarpus tonkinensis, inhibits proliferation and up-regulates HMOX1, SRXN1 and BCAS3 in acute myeloid leukemia

The leaves of Artocarpus tonkinensis are used in Vietnamese traditional medicine for treatment of arthritis, and the compound maesopsin 4-O-β-D-glucoside (TAT-2), isolated from them, inhibits the proliferation of activated T cells. Our goal was to test the anti-proliferative activity of TAT-2 on the T-cell leukemia, Jurkat, and on the acute myeloid leukemia, OCI-AML. TAT-2 inhibited the growth of OCI-AML (and additional acute myeloid leukemia cells) but not Jurkat cells. Growth inhibition was shown to be due to inhibition of proliferation rather than increase in cell death. Analysis of cytokine release showed that TAT-2 stimulated the release of TGF-β, yet TGF-β neutralization did not reverse the maesopsin-dependent effect. Gene expression profiling determined that maesopsin modulated 19 identifiable genes. Transcription factor CP2 was the gene most significantly modulated. Real-time PCR validated that up-regulation of sulphiredoxin 1 homolog (SRXN1), hemeoxygenase 1 (HMOX1), and breast carcinoma amplified sequence 3 (BCAS3) were consistently modulated.

Altered nucleophosmin transport in acute myeloid leukaemia with mutated NPM1: molecular basis and clinical implications

Nucleophosmin (NPM1) is a highly conserved nucleo-cytoplasmic shuttling protein that shows a restricted nucleolar localization. Mutations of NPM1 gene leading to aberrant cytoplasmic dislocation of nucleophosmin (NPMc+) occurs in about one third of acute myeloid leukaemia (AML) patients that exhibit distinctive biological and clinical features. We discuss the latest advances in the molecular basis of nucleophosmin traffic under physiological conditions, describe the molecular abnormalities underlying altered transport of nucleophosmin in NPM1-mutated AML and present evidences supporting the view that cytoplasmic nucleophosmin is a critical event for leukaemogenesis. We then outline how a highly specific immunohistochemical assay can be exploited to diagnose NPM1-mutated AML and myeloid sarcoma in paraffin-embedded samples by looking at aberrant nucleophosmin accumulation in cytoplasm of leukaemic cells. This procedure is also suitable for detection of haemopoietic multilineage involvement in bone marrow trephines. Moreover, use of immunohistochemistry as surrogate for molecular analysis can serve as first-line screening in AML and should facilitate implementation of the 2008 World Health Organization classification of myeloid neoplasms that now incorporates AML with mutated NPM1 (synonym: NPMc+ AML) as a new provisional entity. Finally, we discuss the future therapeutic perspectives aimed at reversing the altered nucleophosmin transport in AML with mutated NPM1.

Cell line OCI/AML3 bears exon-12 NPM gene mutation-A and cytoplasmic expression of nucleophosmin

We recently identified a new acute myeloid leukemia (AML) subtype characterized by mutations at exon-12 of the nucleophosmin (NPM) gene and aberrant cytoplasmic expression of NPM protein (NPMc+). NPMc+ AML accounts for about 35% of adult AML and it is associated with normal karyotype, wide morphological spectrum, CD34-negativity, high frequency of FLT3-ITD mutations and good response to induction therapy. In an attempt to identify a human cell line to serve as a model for the in vitro study of NPMc+ AML, we screened 79 myeloid cell lines for mutations at exon-12 of NPM. One of these cell lines, OCI/AML3, showed a TCTG duplication at exon-12 of NPM. This mutation corresponds to the type A, the NPM mutation most frequently observed in primary NPMc+ AML. OCI/AML3 cells also displayed typical phenotypic features of NPMc+ AML, that is, expression of macrophage markers and lack of CD34, and the immunocytochemical hallmark of this leukemia subtype, that is, the aberrant cytoplasmic expression of NPM. The OCI/AML3 cell line easily engrafts in NOD/SCID mice and maintains in the animals the typical features of NPMc+ AML, such as the NPM cytoplasmic expression. For all these reasons, the OCI/AML3 cell line represents a remarkable tool for biomolecular studies of NPMc+ AML.

T cell regulation of p62(dok) (Dok1) association with Crk-L

In addition to engagement of the T cell receptor-CD3 complex, T lymphocytes can be activated by a variety of cell surface molecules including the approximately 50-kDa surface receptor CD2. While the majority of biochemical signaling elements are triggered by either CD2 or TcR-CD3 receptors, a small number of proteins are engaged by only one receptor. Recently, p62(dok) (Dok1), a member of the Dok family of adapter molecules, has been reported to be activated by CD2 and not by CD3 engagement. Here we have examined the role of p62(dok) in CD2-dependent signaling in Jurkat T cells. As previously reported, we find that ligation of the CD2 molecule by mitogenic pairs of anti-CD2 mAbs led to phosphorylation of p62(dok). While CD2-induced p62(dok) tyrosine phosphorylation was independent of both the p36/38 membrane adapter protein linker of activated T cells (LAT) and the ZAP70/Syk family of kinases, it was dependent upon the Src family of kinases including Lck and Fyn. We find further that CD2 engagement induced the association of tyrosine-phosphorylated p62(dok) to Crk-L. The CD2-dependent association of p62(dok) to Crk-L was independent of expression of the ZAP70/Syk family of kinases. Of note, while T cell receptor-CD3 engagement did not induce either p62(dok) phosphorylation or Crk-L association in Jurkat T cells, it did inhibit CD2-dependent p62(dok)-Crk-L complexes; this TcR-CD3-mediated regulation was dependent upon ZAP70 kinase activity. Our data suggest that phosphorylation of p62(dok) and its interaction with other signaling proteins may depend upon integrated signals emanating from the CD2 receptor, utilizing a ZAP70/LAT-independent pathway, and the TcR-CD3 receptor, which is ZAP70/Syk-dependent.

The involvement of the proto-oncogene p120 c-Cbl and ZAP-70 in CD2-mediated T cell activation

The CD2 co-receptor expressed on the surface of T lymphocytes is able to stimulate T cell activation, proliferation and cytokine production in the absence of direct engagement of the antigen-specific TCR. Engagement of human CD2 by mitogenic pairs of anti-CD2 mAb induces tyrosine phosphorylation of a number of intracellular proteins including a 120 kDa phosphoprotein that we identify as the proto-oncogene c-Cbl. Rapidly tyrosine phosphorylated following stimulation of a number of cell surface receptors, c-Cbl is an adaptor protein that has been shown to associate with a complex of intracellular signaling molecules, and to mediate both positive and negative regulatory effects. Here we show that, like TCR-CD3 stimulation, stimulation of CD2 enhanced the association of c-Cbl with both Crk(L) and the p85 subunit of phosphatidylinositol-3 kinase. Overexpression of wild-type c-Cbl protein inhibited both CD2and CD3-induced NF-AT transcriptional activity, suggesting that CD2 signaling is also negatively regulated by c-Cbl. The inhibitory effect of c-Cbl depended upon its N-terminal phosphotyrosine-binding domain, the domain that has been shown to be required for inhibition of the Syk/ZAP-70 family kinases. In Syk(-) Jurkat T cells stably expressing wild-type ZAP-70, CD2 stimulation induced only a minimal increase in ZAP-70 tyrosine phosphorylation. Nevertheless, ZAP-70 kinase was required for CD2-mediated NF-AT transcriptional activity. Thus, CD2-mediated NF-AT transcriptional activity appears to depend upon ZAP-70/Syk kinases and to be negatively regulated by c-Cbl.

Signaling via LAT (linker for T-cell activation) and Syk/ZAP70 is required for ERK activation and NFAT transcriptional activation following CD2 stimulation

Activation of T cells can be initiated through cell surface molecules in addition to the T-cell receptor-CD3 (TCR-CD3) complex. In human T cells, ligation of the CD2 molecule by mitogenic pairs of anti-CD2 monoclonal antibodies activates T cells via biochemical signaling pathways similar but not identical to those elicited on TCR engagement. This study describes a key role for the p36/38 membrane adapter protein linker for T cell activation (LAT) in CD2-mediated T-cell activation. Following ligation of CD2 on the surface of the Jurkat T-cell line and human purified T cells, LAT was tyrosine phosphorylated and shown to associate in vivo with a number of other tyrosine phosphorylated proteins including PLCgamma-1, Grb-2, and SLP-76. Using Jurkat cell lines deficient in ZAP70/Syk (P116) or LAT (ANJ3) expression, CD2-dependent PLCgamma-1 and SLP-76 tyrosine phosphorylation required expression both of ZAP70 or Syk and of LAT. As predicted, the absence of either LAT or ZAP70/Syk kinases correlated with a defect in the induction of nuclear factor of activated T cells (NFAT) transcriptional activity, activation of the interleukin-2 promoter, and ERK phosphorylation following CD2 stimulation. These data suggest that LAT is an adapter protein important for the regulation of CD2-mediated T-cell activation.

Molecular and cytogenetic remission in a case of subtype M4E acute myelogenous leukemia with minimal monochemotherapy: high sensitivity or spontaneous remission?

Complete remission was observed in an adult patient with acute myelogenous leukemia after minimal monochemotherapy. Remission occurred after a severe febrile pneumonia and was accompanied by cytogenetic and molecular remission. The hypothesis of spontaneous remission was raised, even if a high sensitivity to low-dose cytostatics cannot be excluded. Such spontaneous complete remissions, often associated with bacterial infections and blood transfusions, are extremely rare, and are usually of short duration. Previous cases are summarized, and the role of etiologic factors is discussed.

Failure of gelsolin overexpression to regulate lymphocyte apoptosis

The actin regulatory protein gelsolin cleaves actin filaments in a calcium- and polyphosphoinositide-dependent manner. Gelsolin has recently been described as a novel substrate of the cysteinyl protease caspase-3, an effector protease activated during apoptosis. Cleavage by caspase-3 generates an amino-terminal fragment of gelsolin that can sever actin filaments independently of calcium regulation. The disruption of the actin cytoskeleton by cleaved gelsolin is hypothesized to mediate many of the downstream morphological changes associated with apoptosis. In contrast, overexpression of full-length gelsolin has also been reported to inhibit apoptotic cell death upstream of the activation of caspase-3, suggesting that gelsolin may also act prior to commitment to cell death. The authors previously observed that actin stabilization by the cell permeant agent jasplakinolide enhanced cell death upon interleukin (IL)-2 or IL-3 withdrawal from growth-factor-dependent lymphocyte cell lines, and hypothesized that actin polymerization could alter the activity of gelsolin, thus enhancing apoptosis. Here the authors show that constitutive overexpression of gelsolin did not, however, inhibit or dramatically enhance apoptotic cell death upon growth-factor withdrawal, nor did it modify sensitivity to jasplakinolide. In contrast to previous reports, overexpression of gelsolin in Jurkat T cells did not prevent or delay apoptosis induced by Fas ligation or ceramide treatment. Overexpressed gelsolin protein was cleaved during apoptosis, as seen previously in this and other cell types. In these model systems, therefore, the level of gelsolin expression was not a rate-limiting determinant in commitment to or time to the morphological changes of apoptosis.

Treatment and clinical management of primary mediastinal large B-cell lymphoma with sclerosis: MACOP-B regimen and mediastinal radiotherapy monitored by (67)Gallium scan in 50 patients

To evaluate the efficacy of a combined modality treatment (MACOP-B plus mediastinal radiotherapy) and the advantages of Gallium-67-citrate single-photon emission ((67)GaSPECT) over computed tomography (CT) for restaging in patients with primary mediastinal large B-cell lymphoma (PMLBCL) with sclerosis. Between 1989 and 1998, 50 previously untreated patients with PMLBCL with sclerosis (70% with bulky mass) were treated with MACOP-B regimen plus mediastinal radiotherapy. The radiologic clinical stage with evaluation of tumor size included CT and (67)GaSPECT at diagnosis, after chemotherapy, and after radiotherapy. Forty-three patients (86%) achieved a complete response and 7 were nonresponders to treatment. For the imaging evaluation, only 47 patients were evaluable because 3 had disease progression during chemotherapy. After treatment, 3/5 (60%) patients with positive (67)GaSPECT and negative CT scan relapsed, as against 0/21 (0%) with negative (67)GaSPECT and CT scan. Twenty-one patients had a positive CT scan: of these, the 4 with positive (67)GaSPECT all progressed, whereas there were no relapses among the 17 with negative (67)GaSPECT. After radiotherapy, there was a decrease of positive CT (from 33 to 21 cases) and of positive (67)GaSPECT (from 31 to 9 cases). Relapse-free survival rate was 93% at 96 months (median 39 months). In patients with PMLBCL with sclerosis, MACOP-B plus radiation therapy is a very useful first-line treatment and radiation therapy may play an important role. As regards restaging, (67)GaSPECT should be considered the imaging technique of choice at least in patients who show CT positivity.

Improved outcome with T-cell-depleted bone marrow transplantation for acute leukemia

PURPOSE

To eliminate the risk of rejection and lower the risk of relapse after T-cell-depleted bone marrow transplants in acute leukemia patients, we enhanced pretransplant immunosuppression and myeloablation.

PATIENTS AND METHODS

Antithymocyte globulin and thiotepa were added to standard total-body irradiation/cyclophosphamide conditioning. Donor bone marrows were depleted ex vivo of T lymphocytes by soybean agglutination and E-rosetting. This approach was tested in 54 consecutive patients with acute leukemia who received transplants from HLA-identical sibling donors or, in two cases, from family donors mismatched at D-DR. No posttransplant immunosuppressive treatment was given as graft-versus-host disease (GVHD) prophylaxis.

RESULTS

Neither graft rejection nor GVHD occurred. Transplant-related deaths occurred in six (16.6%) of 36 patients in remission and in seven (38.8%) of 18 patients in relapse at the time of transplantation. The probability of relapse was .12 (95% confidence interval [CI], 0 to .19) for patients with acute myeloid leukemia and .28 (95% CI, .05 to .51) for patients with acute lymphoblastic leukemia who received transplants at the first or second remission. At a median follow-up of 6.9 years (minimum follow-up, 4.9 years), event-free survival for patients who received transplants while in remission was .74 (95% CI, .54 to .93) for acute myeloid leukemia patients and .59 (95% CI, .35 to .82) for acute lymphoblastic leukemia patients. All surviving patients have 100% performance status.

CONCLUSION

Adding antithymocyte globulin and thiotepa to the conditioning regimen prevents rejection of extensively T-cell-depleted bone marrow. Even in the complete absence of GVHD, the leukemia relapse rate is not higher than in unmanipulated transplants.

Immunophenotype of adult and childhood acute promyelocytic leukaemia: correlation with morphology, type of PML gene breakpoint and clinical outcome. A cooperative Italian study on 196 cases

Acute promyelocytic leukaemia (APL), characterized by a specific PML-RARalpha fusion gene resulting from translocation t(15;17) and by a high response rate to differentiation therapy with all-trans retinoic acid, presents clinical (varying WBC counts, age and treatment outcome), morphological (hypergranular M3 and hypogranular M3V) and molecular (three isoforms of PML breakpoint) heterogeneity. We correlated leukaemic immunophenotype with these aspects in 196 molecularly confirmed APLs (63 children and 133 adults) in Italy. The bcr3 isoform (P = 0.05) and FAB M3V (P = 0.05) were more frequent in children. We confirmed in APL an immunophenotype characterized by frequent expression of CD13, CD33 and CD9 and rare expression of HLA-DR, CD10, CD7 and CD11b. However, we recognized CD2 in 28%, CD34 in 23% and CD19 in 11% of cases and demonstrated by double labelling that CD34 and CD2 may be co-expressed. CD2, CD34 and CD19 were significantly intercorrelated, and variably associated to other features: CD2 and CD34 with PML bcr3 (P < 0.001 and P < 0.001, respectively) and with M3V (P < 0.001 and P = 0.002), whereas only CD19 was directly correlated with WBC counts and only CD2 positively influenced CR rate (logistic model) and event-free survival (Cox model). We conclude that immunophenotype plays a role in the determination of the biological and clinical heterogeneity of childhood and adult APL.

MACOP-B and involved field radiation therapy is an effective therapy for primary mediastinal large B-cell lymphoma with sclerosis

PURPOSE

To evaluate the clinical features of presentation and the response to two different third-generation regimens (F-MACHOP and MACOP-B) of primary mediastinal large B-cell lymphoma (MLBCL), a recently defined distinct clinicopathological entity of non-Hodgkin's lymphoma (NHL).

PATIENTS AND METHODS

Thirty-seven consecutive patients with MLBCL, eight male and 29 female (F/M ratio 1:3.5) with a median age of 35 years, were enrolled in the present study. Thirty-five (94.5%) patients presented disease confined to thorax, with chest symptoms of a rapidly enlarging mass in the mediastinum in 70% and superior vena cava syndrome (SCVS) in 43% of these patients. The first 10 patients received F-MACHOP and the succeeding 27 patients MACOP-B chemotherapy, associated in 24 (88.8%) with involved field radiation therapy (IFRT). 67Gallium scan was routinely performed pre- and post-IFRT in 18 patients.

RESULTS

All 37 patients were assessable for response: 10 of 10 (100%) in the F-MACHOP and 26 of 27 (96.3%) in the MACOP-B group achieved overall responses (CR + PR). Three of 24 (12.5%) patients in PR after chemotherapy obtained CR after IFRT. Persistent Gallium avidity was observed in 16 patients after chemotherapy and in only four patients after IFRT. Thus far, four of the 10 F-MACHOP and two of the 26 MACOP-B responders have presented disease progression. The probability of progression-free survival (PFS) was 91% and 60% (P < 0.02) while overall survival (OS) was 93% and 70% (P = n.s.) at a mean follow-up of 27 and 52 months in the MACOP-B + IFRT and F-MACHOP groups, respectively.

CONCLUSION

MACOP-B + IFRT has proved to be a highly effective and less toxic therapeutic approach for primary MLBCL and appears to be superior to other third-generation chemotherapy regimens.

Stem cell mobilization in normal donors

We studied peripheral blood and apheresis samples from 39 consecutive normal donors who were parents or siblings of patients who received matched or mismatched bone marrow transplants using a combination of rhG-CSF-mobilized peripheral blood stem cells (PBSCs) and bone marrow (BM). BM was harvested from donors 1-7 days before starting rhG-CSF treatment: 12 micrograms/kg/day rhG-CSF was administered by continuous s.c. infusion for 4-7 days. Peripheral blood progenitor cells were harvested by leukapheresis using an automated continuous-flow blood cell separator, beginning on day 4 of rhG/CSF, for 1-4 consecutive days. Peak peripheral blood CD34+ cell and CFU-GM levels were reached simultaneously on day 5 or 6 of rhG-CSF administration. Median peak levels were 1.65% for CD34+ cells (range 0.34%-4.7%) and 142 CFU-GM/10(5) plated cells (range 16-700). The greatest numbers of CD34+ cells and CFU-GM, expressed per liter of blood volume processed, were harvested during the second and third leukapheresis: CD34+ cells 37.77 +/- 25.48 x 10(6) and CFU-GM 3.32 +/- 2.51 x 10(6) during the second leukapheresis, and CD34+ cells 37.01 +/- 16.33 x 10(6) and CFU-GM 3.82 +/- 4.36 x 10(6) during the third. The number of CD34+ cells and CFU-GM did not correlate with the sex, age, or body weight of the donors. This study indicates that this protocol for administration of rhG-CSF mobilizes large numbers of hematopoietic progenitor cells into the peripheral blood and that bone marrow harvesting before G-CSF administration does not impair stem cell mobilization.

Multidrug resistance expression and proliferative studies in poor risk acute myeloid leukemia treated with the FLAG (G-CSF plus fludarabine and Ara-C) regimen

Fourteen poor risk acute myeloid leukemia (AML) patients were treated with G-CSF prior (from day 0) and during chemotherapy with fludarabine and Ara-C from day 1 to day 5 (the FLAG regimen). Several biological parameters were monitored on the blast population: multidrug resistance (MDR) functional expression by rhodamine-123 efflux (Rhd-E), cell cycle changes, induction of apoptosis and leukemic clonogenic cell growth (CFU-L). The mean basal Rhd-E value was 14.4% (range 0-51.2), and 12/14 patients exhibited a dye efflux > 4%, efficiently blocked by the MDR-reversal agent cyclosporin A. After 24 h of G-CSF administration, cell cycle studies showed in bone marrow (BM) samples a significant mean increase in S phase (p = 0.04) and in RNA content of G1 cells (p = 0.01), coupled to a significant increase in apoptosis (p = 0.02). Clonogenic cell growth analysis showed a twofold increase in BM CFU-L in 6 of the 14 cases tested. When G-CSF activity was assessed without the addition of exogenous growth factors (autonomous proliferation), a significant increase (p = 0.02) in CFU-L was found only in patients who achieved a complete remission (CR); these patients were also characterized by lower S-phase values at diagnosis. Eight of the 14 patients treated achieved CR, but the median response duration was three months, and only two cases are still in CR. The FLAG regimen can thus induce remission in poor risk AML patients. The responses, however, are short, suggesting that resistant cells are not efficiently affected by either the use of agents not involved in the MDR-efflux mechanism or by the G-CSF priming strategy. Other post-induction therapies need to be considered in further approaches.

Successful engraftment of T-cell-depleted haploidentical "three-loci" incompatible transplants in leukemia patients by addition of recombinant human granulocyte colony-stimulating factor-mobilized peripheral blood progenitor cells to bone marrow inoculum

Patients who undergo transplantation with haploidentical "three-loci" mismatched T-cell-depleted bone marrow (BM) are at high risk for graft failure. To overcome the host-versus-graft barrier, we increased the size of the graft inoculum, which has been shown to be a major factor in controlling both immune rejection and stem cell competition in murine models. Seventeen patients (mean age, 23.2 years; range, 6 to 51 years) with end-stage chemoresistant leukemia were received transplants of a combination of BM with recombinant human granulocyte colony-stimulating factor-mobilized peripheral blood progenitor cells from HLA-haploidentical "three-loci" incompatible family members. The average concentration of colony-forming unit-granulocyte-macrophage in the final inoculum was sevenfold to 10-fold greater than that found in BM alone. The sole graft-versus-host disease (GVHD) prophylaxis consisted of T-cell depletion of the graft by the soybean agglutination and E-rosetting technique. The conditioning regimen included total body irradiation in a single fraction at a fast dose rate, antithymocyte globulin, cyclophosphamide and thiotepa to provide both immunosuppression and myeloablation. One patient rejected the graft and the other 16 had early and sustained full donor-type engraftment. One patient who received a much greater quantity of T lymphocytes than any other patient died from grade IV acute GVHD. There were no other cases of GVHD > or = grade II. Nine patients died from transplant-related toxicity, 2 relapsed, and 6 patients are alive and event-free at a median follow-up of 230 days (range, 100 to 485 days). Our results show that a highly immunosuppressive and myeloablative conditioning followed by transplantation of a large number of stem cells depleted of T lymphocytes by soybean agglutination and E-rosetting technique has made transplantation of three HLA-antigen disparate grafts possible, with only rare cases of GVHD.

[Epidemiology of toxoplasmosis. Results of 5 years of serodiagnostic surveys]

The results obtained by antibodies titration in 1500 subjects, in connection with Toxoplasma infection, are discussed. The determinant influence of some factors is statistically evaluated and recent Italian and foreign results are considered, according to the epidemiology of Toxoplasmosis.