Immunohematologic reconstitution in pediatric patients after T cell-depleted HLA-haploidentical stem cell transplantation for thalassemia.

To analyze immunohematologic reconstitution, particularly of natural killer (NK) cells, we evaluated 13 ß-thalassemia patients after 20 and 60 days and 1 year posttransplantation with T cell-depleted HLA-haploidentical stem cells. We assessed lymphocyte and bone marrow (BM) progenitor cell phenotype and differentiation capacity, spontaneous BM cytokine production, stromal cells, and stromal cell interleukin (IL)-7 production. A reduced clonogenic capability manifested at day +20. Patients had significantly lower CD4(+) T cells versus controls, mainly in the CD45RA(+)CD62L(+) subset. NKs were among the first lymphocytes to repopulate the peripheral blood. At day +60, an increase in primitive BM progenitor cells paralleled small increases in CD4(+), naïve CD4(+), and thymic naïve Th cells. A significant increase in CD4(+) and CD8(+) markers paralleled an increase in CD3⁻CD16(+) NKs, especially with full engraftment. In patients with stable mixed chimerism we observed very low levels of CD3(+) donor chimerism early after transplant that increased over time, but a stable population of high donor NK cells, suggesting a role of these cells on donor engraftment. Stromal cells secreted less IL-7 and displayed "macrophage-like" morphology. Patients initially manifested impaired stem/progenitor cell growth and differentiation capacity in parallel with altered T cell homeostasis and a reduced T cell naïve compartment. We hypothesize that T cell compartment damage partly arises from altered new T cell production from the hematopoietic stem/progenitor cells under stromal cytokine influence. NNK subset analysis might be useful for determining transplant outcome.

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.

Association of hepcidin promoter c.-582 A>G variant and iron overload in thalassemia major.

Hepcidin is a 25-amino acid peptide, derived from cleavage of an 84 amino acid pro-peptide produced predominantly by hepatocytes. This molecule, encoded by the hepcidin antimicrobial peptide (HAMP) gene shows structural and functional properties consistent with a role in innate immunity. Moreover, as demonstrated in mice and humans, hepcidin is a major regulator of iron metabolism, and acts by binding to ferroportin and controlling its concentration and trafficking. In this study we investigated the influence that mutations in HAMP and/or hemocromatosis (HFE) genes might exert on iron metabolism in a group of poly-transfused thalassemic patients in preparation for bone marrow transplantation. Our results showed that the presence of the c.-582 A>G polymorphism (rs10421768) placed in HAMP promoter (HAMP-P) might play a role in iron metabolism, perhaps varying the transcriptional activation that occurs through E-boxes located within the promoter.

Excretion of the novel polyomaviruses KI and WU in the stool of patients with hematological disorders.

Infection with human polyomaviruses BKV and JCV is asymptomatic, and lifelong and widespread, among the general population. However, in the setting of immunosuppression, secondary to medications or viral infection, for example, with HIV, reactivation can occur and result in severe disease. In this study, stool specimens from 31 patients with hematological disorders (25 transplanted and 6 non-transplanted) were examined prospectively to determine whether the novel polyomaviruses KIV and WUV reactivated and were excreted in the gastrointestinal tract. Reactivation was correlated with the appearance of gastrointestinal and respiratory symptoms. Of the 31 patients examined, KIV and WUV were detected in 13 transplanted patients as single infection or in combination with BKV, cytomegalovirus (CMV), and adenovirus (Adv). Because of frequent co-infections, a clear correlation between novel polyomaviruses and clinical symptoms could not be established. There was no correlation between demographic variables and detection of KIV and WUV. Phylogenetic analysis of the small t-antigen gene of KIV and WUV isolates showed that the novel polyomaviruses identified in feces clustered with those identified in the respiratory tract suggesting an oral-fecal transmission of these viruses. The novel polyomaviruses KI and WU may have a pathogenic role in immunocompromised patients.

Relationship between mixed chimerism and rejection after bone marrow transplantation in thalassaemia.

BACKGROUND: Thalassaemia is a genetic disease that requires a hypertransfusion regimen to treat the anaemia caused by enhanced red blood cell destruction. The only radical cure for thalassaemia is to correct the genetic defect by bone marrow transplantation from an HLA-identical donor capable of producing and maintaining a normal haemoglobin level in the recipient. Complete donor haematopoiesis is not essential for sustained engraftment and the simultaneous presence of haematopoietic cells of both donor and recipient origin is not a rare event after a transplant. PATIENTS AND METHODS: The evolution of marrow engraftment of 93 transplanted thalassaemic patients, all from Middle East or Asian countries, was monitored by analysis of short tandem repeats. RESULTS: Forty-three of 93 (46%) patients experienced a status of mixed chimerism early after bone marrow transplantation. Results of further engraftment analysis in these patients showed in 27 complete donor engraftment; rejection occurred in seven, while eight maintained the presence of both host and donor-derived cells. Interestingly, five out of the seven patients who rejected their transplant showed more than 25% residual host cells early after transplantation. DISCUSSION AND CONCLUSION: Our study confirmed that the presence of large amounts of residual host cells within the first 2 months after a transplant is a risk factor for graft rejection also in a group of patients with wide ethnic heterogeneity, irregular transfusion regimens and/or poor chelation treatment. Ten percent of the transplanted thalassaemic patients maintained coexistence of donor and recipient cells, showing a stable functional graft, characterized by normal production of beta globin chains and high levels of haemoglobin. A mechanism responsible for peripheral tolerance induction, such as the production of specific regulatory T-cell clones, seems to play a key role in the induction of long-term tolerance after the transplant.

Bone marrow transplantation in adults with thalassemia: Treatment and long-term follow-up.

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.

New approach for bone marrow transplantation in patients with class 3 thalassemia aged younger than 17 years.

When prepared for transplantation with busulfan (BU) 14 mg/kg and cyclophosphamide (CY) 120 to 160 mg/kg, patients with thalassemia in risk class 3, aged younger than 17 years, who receive transplants from HLA-identical donors, had a 30% incidence of transplant rejection with recurrence of thalassemia. This, relatively poor, outcome was ascribed to insufficient immune suppression or to inadequate eradication of the thalassemic marrow, or both. In an attempt to enhance both immune suppression and eradication of the thalassemic clones, hydroxyurea, azathioprine, and fludarabine were added to the BU and CY. This regimen, called protocol 26, was applied to 33 consecutive patients with class 3 thalassemia aged younger than 17 years and was well tolerated with 93% survival. The incidence of recurrent thalassemia after the transplantation decreased from 30% to 8%.