Marco Andreani

Coexpression of CD49b and LAG-3 identifies human and mouse T regulatory type 1 cells

CD4+ type 1 T regulatory (Tr1) cells are induced in the periphery and have a pivotal role in promoting and maintaining tolerance. The absence of surface markers that uniquely identify Tr1 cells has limited their study and clinical applications. By gene expression profiling of human Tr1 cell clones, we identified the surface markers CD49b and lymphocyte activation gene 3 (LAG-3) as being stably and selectively coexpressed on mouse and human Tr1 cells. We showed the specificity of these markers in mouse models of intestinal inflammation and helminth infection and in the peripheral blood of healthy volunteers. The coexpression of CD49b and LAG-3 enables the isolation of highly suppressive human Tr1 cells from in vitro anergized cultures and allows the tracking of Tr1 cells in the peripheral blood of subjects who developed tolerance after allogeneic hematopoietic stem cell transplantation. The use of these markers makes it feasible to track Tr1 cells in vivo and purify Tr1 cells for cell therapy to induce or restore tolerance in subjects with immune-mediated diseases.

Marrow Transplantation in Patients with Thalassemia Responsive to Iron Chelation Therapy

BACKGROUND Patients with homozygous beta-thalassemia, who have a good prognosis during treatment with conventional therapy, appear to have an especially high probability of hematologic cure with bone marrow transplantation, although the morbidity and mortality associated with such treatment are not established. METHODS The records of all patients with thalassemia who received bone marrow transplants from HLA-identical donors in Pesaro, Italy, were examined from October 1982 through May 1992. Detailed evaluation of the outcome was conducted in the 89 patients identified as being in class 1 according to the Pesaro classification, in which hepatomegaly, portal fibrosis, and the inadequacy of iron chelation therapy are considered independent risk factors, and the patients are classified as being in class 1 if none of these factors are present, class 2 if one or two of the factors are present, and class 3 if all three factors are present. Sixty-four of the patients had been prepared for transplantation with a drug regimen in current use that includes busulfan and cyclophosphamide followed by cyclosporine as prophylaxis against acute graft-versus-host disease (protocol 6). RESULTS There were seven deaths, all within 101 days of transplantation. Two of the 64 patients treated according to protocol 6 died. The probabilities of survival, rejection-free survival, death from causes unrelated to rejection, and rejection were 0.92, 0.85, 0.06, and 0.08, respectively, in the total group and 0.97, 0.93, 0.03, and 0.04 in the 64 patients treated according to protocol 6. Preliminary evidence suggests that there was useful unloading of tissue iron deposits. CONCLUSIONS The high probability of cure with little early or late morbidity and mortality suggests that patients with class 1 thalassemia who have HLA-identical donors available should be treated by bone marrow transplantation. However, this was not a controlled trial, so we cannot directly compare the outcome with that of conventional treatment.

Haploidentical, unmanipulated, G-CSF–primed bone marrow transplantation for patients with high-risk hematologic malignancies

UNLABELLED Eighty patients with high-risk hematologic malignancies underwent unmanipulated, G-CSF–primed BM transplantation from an haploidentical family donor. Patients were transplanted in first or second complete remission (CR, standard-risk: n =45) or in > second CR or active disease (high-risk: n =35). The same regimen for GVHD prophylaxis was used in all cases. The cumulative incidence (CI) of neutrophil engraftment was 93% 0.1%. The 100-day CIs for II-IV and III-IV grade of acute GVHD were 24% 0.2% and 5% 0.6%, respectively. The 2-year CI of extensive chronic GVHD was 6% 0.1%. The 1-year CI of treatment-related mortality was 36% 0.3%. After a median follow-up of 18 months, 36 of 80 (45%) patients are alive in CR. The 3-year probability of overall and disease-free survival for standard-risk and high-risk patients was 54% 8% and 33% 9% and 44% 8% and 30% 9%, respectively. In multivariate analysis, disease-free survival was significantly better for patients who had standard-risk disease and received transplantations after 2007. We conclude that unmanipulated, G-CSF–primed BM transplantation from haploidentical family donor provides very encouraging results in terms of engraftment rate, incidence of GVHD and survival and represents a feasible, valid alternative for patients with high-risk malignant hematologic diseases, lacking an HLA identical sibling and in need to be urgently transplanted. KEY POINTS Haploidentical, unmanipulated, G-CSF-primed bone marrow transplantation. Haploidentical hematopoietic stem cell transplantation for hematologic malignancies.

Long-term survival of ex-thalassemic patients with persistent mixed chimerism after bone marrow transplantation

Twenty-six transplanted thalassemic patients out of 295 analyzed, showed the presence of persistent mixed chimerism, over a period of time varying between 2 and 11 years after BMT. Despite the presence of large numbers of residual host cells, these transplanted thalassemic patients no longer require red blood cell transfusions and have a functional graft, producing sufficient levels of hemoglobin A ranging from 8.3–14.7 g/dl. These ex-thalassemic patients with persistent mixed chimerism, although they did not achieve complete donor engraftment are no longer exposed to the risk of graft rejection. The mechanisms underlying this apparent state of tolerance or education in these patients are at the present time unknown. However, these observations may be useful for physicians involved in defining optimal strategies for clinical gene therapy, in uterohematopoietic stem cell transplantation and adoption of less toxic conditioning regimens in mini-transplantation. Bone Marrow Transplantation (2000) 25, 401–404.

Bone marrow transplantation from alternative donors for thalassemia: HLA-phenotypically identical relative and HLA-nonidentical sibling or parent transplants

Twenty-nine patients with thalassemia and a median age of 6 years (range 1.1–33 years) were given a BMT from an alternative donor. Six of the 29 donors were HLA-phenotypically identical and two were mismatched relatives, 13 were mismatched siblings and eight were mismatched parents. Six patients received no antigen (relatives), 15 patients one antigen, five patients two antigen and three patients three antigen disparate grafts. Twenty-three patients were in class 2 or class 3, whereas six patients were in class 1. Thirteen patients were given BUCY, nine patients BUCY plus ALG, six patients BUCY plus TBI or TLI and one patient BUCY with prior cytoreductive-immunosuppressive treatment as conditioning. As GVHD prophylaxis four patients received MTX, 22 CsA + MTX + methylprednisolone (MP) and three patients CsA + MP. Thirteen of 29 patients (44.8%) had sustained engraftment. The probability of graft failure or rejection was 55%. There were no significant differences between antigen disparities and graft failure. The incidence of grade II–IV acute GVHD was 47.3% and chronic GVHD was 37.5%. The incidence of acute GVHD was higher in patients receiving one or two antigen disparate in the GVHD direction grafts (vs no antigen) (P EQ 0.04; odds ratio 10.8; 95% CI 1.5–115). The probability of overall and event-free survival was 65% and 21%, respectively, with median follow-up of 7.5 years (range 0.6–17 years) for surviving patients. The degree of HLA disparity between patient and donor did not have a significant effect on survival. The incidence of nonhematologic toxicity was low. Transplant-related mortality was 34%. GVHD (acute or chronic) was a major contributing cause of death (50%) followed by infections (30%). We conclude that at present, due to high graft failure and GVHD rates, BMT from alternative donors should be restricted to patients who have poor life expectancies because they cannot receive adequate conventional treatment or because of alloimmunization to minor blood antigens. Bone Marrow Transplantation (2000) 25, 815–821.

Bone Marrow Transplantation in Adults with Thalassemia: Treatment and Long‐Term Follow‐Up

Abstract: Current regular blood transfusion programs and chelation treatment have considerably improved survival of patients with thalassemia, which resulted in a larger proportion of adult patients. However, disease‐ and treatment‐related complications in these patients progress over time, causing severe morbidity and shortened life expectancy. Stem cell transplantation still remains the only cure currently available for patients with thalassemia. This study updates transplant outcomes in 107 adult patients with median age of 22 years (range, 17‐35 years) who received bone marrow transplantation (BMT) from human leukocyte antigen (HLA)‐identical related donors between 1988 and 1996 (group A) and describes the results of BMT in 15 adult patients with median age of 21 years (range, 17‐31 years) who were treated with a new treatment protocol (Protocol 26) between 1997 and 2003 (group B). The probability of survival, event‐free survival, nonrejection mortality, and rejection for group A patients were 66%, 62%, 37%, and 4%, respectively, with a median follow‐up of 12 years (range, 8.3‐16.2 years). Group B patients treated with the new protocol had some improvement in thalassemia‐free survival (67%) and lower transplant‐related mortality (27%) than that of previous protocols. However, transplant‐related mortality in these high‐risk patients remains elevated. Current myeloablative BMT in adult patients is characterized by higher transplant‐related toxicity due to an advanced phase of disease. Although this new approach to transplant adult patients with a reduced‐dose intensity‐conditioning regimen has improved thalassemia‐free survival, transplant‐related mortality in these high‐risk patients remains elevated.

Killing of myeloid APCs via HLA class I, CD2 and CD226 defines a novel mechanism of suppression by human Tr1 cells

IL‐10‐producing CD4+ type 1 regulatory T (Tr1) cells, defined based on their ability to produce high levels of IL‐10 in the absence of IL‐4, are major players in the induction and maintenance of peripheral tolerance. Tr1 cells inhibit T‐cell responses mainly via cytokine‐dependent mechanisms. The cellular and molecular mechanisms underlying the suppression of APC by Tr1 cells are still not completely elucidated. Here, we defined that Tr1 cells specifically lyse myeloid APC through a granzyme B (GZB)‐ and perforin (PRF)‐dependent mechanism that requires HLA class I recognition, CD54/lymphocyte function‐associated antigen (LFA)‐1 adhesion, and activation via killer cell Ig‐like receptors (KIRs) and CD2. Notably, interaction between CD226 on Tr1 cells and their ligands on myeloid cells, leading to Tr1‐cell activation, is necessary for defining Tr1‐cell target specificity. We also showed that high frequency of GZB‐expressing CD4+ T cells is detected in tolerant patients and correlates with elevated occurrence of IL‐10‐producing CD4+ T cells. In conclusion, the modulatory activities of Tr1 cells are not only due to suppressive cytokines but also to specific cell‐to‐cell interactions that lead to selective killing of myeloid cells and possibly bystander suppression.

Purified T-depleted, CD34+ peripheral blood and bone marrow cell transplantation from haploidentical mother to child with thalassemia.

Fetomaternal microchimerism suggests immunological tolerance between mother and fetus. Thus, we performed primary hematopoietic stem cell transplantation from a mismatched mother to thalassemic patient without an human leukocyte antigen-identical donor. Twenty-two patients with thalassemia major were conditioned with 60 mg/kg hydroxyurea and 3 mg/kg azathioprine from day -59 to -11; 30 mg/m(2) fludarabine from day -17 to -11; 14 mg/kg busulfan starting on day -10; and 200 mg/kg cyclophosphamide, 10 mg/kg thiotepa, and 12.5 mg/kg antithymocyte globulin daily from day -5 to -2. Fourteen patients received CD34(+)-mobilized peripheral blood and bone marrow progenitor cells; 8 patients received marrow graft-selected peripheral blood stem cells CD34(+) and bone marrow CD3/CD19-depleted cells. T-cell dose was adjusted to 2 x 10(5)/kg by fresh marrow cell addback at the time of transplantation. Both groups received cyclosporine for graft-versus-host disease prophylaxis for 2 months after transplantation. Two patients died (cerebral Epstein-Barr virus lymphoma or cytomegalovirus pneumonia), 6 patients reject their grafts, and 14 showed full chimerism with functioning grafts at a median follow-up of 40 months. None of the 14 patients who showed full chimerism developed acute or chronic graft-versus-host disease. These results suggest that maternal haploidentical hematopoietic stem cell transplantation is feasible in patients with thalassemia who lack a matched related donor.

Novel pharmacokinetic behavior of intravenous busulfan in children with thalassemia undergoing hematopoietic stem cell transplantation: a prospective evaluation of pharmacokinetic and pharmacodynamic profile with therapeutic drug monitoring

We prospectively studied the pharmacokinetics (PK) and clinical outcomes of intravenous busulfan (Bu) in 71 children with preexisting liver damage who underwent hematopoietic stem cell transplantation for thalassemia. Intravenous Bu was administered every 6 hours as part of a conditioning regimen with PK-based dose adjustment to target a conservative area under the concentration-versus-time curve (AUC) range (900-1350 microMol*min). The first-dose Bu clearance (CL) was significantly higher than the subsequent daily CL that remained unchanged in the ensuing days. One-third of patients required dose escalation based on dose 1 AUC, whereas dose reduction was needed in the subsequent days. At doses 5, 9, and 13, 78%, 81%, and 87% of patients, respectively, achieved the target range of AUC. A population PK analysis confirmed that the first-dose CL was 20% higher and that body weight was the most important covariate to explain PK variability. Patients with variant GSTA1*B had a 10% lower Bu CL than wild-type. These results suggest that the disease-specific behavior of intravenous Bu PK should be considered for PK-guided dose adjustment in patients with thalassemia, and the use of a conservative AUC range resulted in low toxicity, good engraftment, and good survival rate.

Tracking human migrations by the analysis of the distribution of HLA alleles, lineages and haplotypes in closed and open populations

The human leucocyte antigen (HLA) system shows extensive variation in the number and function of loci and the number of alleles present at any one locus. Allele distribution has been analysed in many populations through the course of several decades, and the implementation of molecular typing has significantly increased the level of diversity revealing that many serotypes have multiple functional variants. While the degree of diversity in many populations is equivalent and may result from functional polymorphism(s) in peptide presentation, homogeneous and heterogeneous populations present contrasting numbers of alleles and lineages at the loci with high-density expression products. In spite of these differences, the homozygosity levels are comparable in almost all of them. The balanced distribution of HLA alleles is consistent with overdominant selection. The genetic distances between outbred populations correlate with their geographical locations; the formal genetic distance measurements are larger than expected between inbred populations in the same region. The latter present many unique alleles grouped in a few lineages consistent with limited founder polymorphism in which any novel allele may have been positively selected to enlarge the communal peptide-binding repertoire of a given population. On the other hand, it has been observed that some alleles are found in multiple populations with distinctive haplotypic associations suggesting that convergent evolution events may have taken place as well. It appears that the HLA system has been under strong selection, probably owing to its fundamental role in varying immune responses. Therefore, allelic diversity in HLA should be analysed in conjunction with other genetic markers to accurately track the migrations of modern humans.