Paul Szabolcs

Characterization of a rare IL-10–competent B-cell subset in humans that parallels mouse regulatory B10 cells

Regulatory B cells control inflammation and autoimmunity in mice, including the recently identified IL-10-competent B10 cell subset that represents 1% to 3% of spleen B cells. In this study, a comparable IL-10-competent B10 cell subset was characterized in human blood. B10 cells were functionally identified by their ability to express cytoplasmic IL-10 after 5 hours of ex vivo stimulation, whereas progenitor B10 (B10pro) cells required 48 hours of in vitro stimulation before they acquired the ability to express IL-10. B10 and B10pro cells represented 0.6% and approximately 5% of blood B cells, respectively. Ex vivo B10 and B10pro cells were predominantly found within the CD24(hi)CD27(+) B-cell subpopulation that was able to negatively regulate monocyte cytokine production through IL-10-dependent pathways during in vitro functional assays. Blood B10 cells were present in 91 patients with rheumatoid arthritis, systemic lupus erythematosus, primary Sjögren syndrome, autoimmune vesiculobullous skin disease, or multiple sclerosis, and were expanded in some cases as occurs in mice with autoimmune disease. Mean B10 + B10pro-cell frequencies were also significantly higher in patients with autoimmune disease compared with healthy controls. The characterization of human B10 cells will facilitate their identification and the study of their regulatory activities during human disease.

Multicenter study of banked third-party virus-specific T cells to treat severe viral infections after hematopoietic stem cell transplantation

Virus-specific T cell (VST) lines could provide useful antiviral prophylaxis and treatment of immune-deficient patients if it were possible to avoid the necessity of generating a separate line for each patient, often on an emergency basis. We prepared a bank of 32 virus-specific lines from individuals with common HLA polymorphisms who were immune to Epstein-Barr virus (EBV), cytomegalovirus, or adenovirus. A total of 18 lines were administered to 50 patients with severe, refractory illness because of infection with one of these viruses after hematopoietic stem cell transplant. The cumulative rates of complete or partial responses at 6 weeks postinfusion were 74.0% (95% CI, 58.5%-89.5%) for the entire group (n = 50), 73.9% (95% CI, 51.2% -96.6%) for cytomegalovirus (n = 23), 77.8% for adenovirus (n = 18), and 66.7% (95% CI, 36.9%-96.5%) for EBV (n = 9). Only 4 responders had a recurrence or progression. There were no immediate infusion-related adverse events, and de novo graft-versus-host disease developed in only 2 patients. Despite the disparity between the lines and their recipients, the mean frequency of VSTs increased significantly postinfusion, coincident with striking decreases in viral DNA and resolution of clinical symptoms. The use of banked third-party VSTs is a feasible and safe approach to rapidly treat severe or intractable viral infections after stem cell transplantation. This study is registered at www.clinicaltrials.gov as NCT00711035.

Risk factor analysis of outcomes after unrelated cord blood transplantation in patients with hurler syndrome.

Allogeneic stem cell transplantation (SCT) is considered effective in preventing disease progression in patients with Hurler syndrome (HS). Unrelated umbilical cord blood (UCB) grafts are suggested as an alternative to bone marrow (BM) or peripheral blood stem cells (PBSC). We studied 93 HS patients receiving an UCB graft to analyze risk factors for outcomes. The median time from diagnosis to transplant was 4.6 months, median follow-up was 29 months, and median number of nucleated CB cells infused was 7.6 x 10(7)/kg. Most of the patients received 1 or 2 HLA disparate grafts, and the most frequently used conditioning regimen was cyclophosphamide + busulfan (Bu/Cy). All patients received anti-T cell antibody. At post transplant day +60, the cumulative incidence of neutrophil engraftment was 85%. A younger age at transplant and a higher CD34(+) dose at infusion were favorably associated with engraftment. With the exception of 2 patients, all engrafted patients achieved full and sustained donor chimerism. The 3-year event-free survival (EFS) and 3-year overall survival (OS) rates were 70% and 77%, respectively. In a multivariate analyses, use of Bu/Cy and a shorter interval from diagnosis to transplant were predictors for improved EFS rate (82% for patients transplanted within 4.6 months after diagnosis compared to 57% for the rest). Improved outcomes from early transplantation and immediate availability of CB unit lead us to conclude that CB transplantation is a beneficial option, which should be considered expediently for children with HS.

Unrelated cord blood transplantation in children with sickle cell disease: Review of four-center experience

Abstract:  UCBT was performed in seven children with SCD and stroke (HLA match 4/6 n = 5; 5/6 n = 2). Four received myeloablative regimens (BU, CY, ATG plus FLU in one patient). One had primary graft failure, three had sustained engraftment, two with grade III–IV GVHD (one died, one developed chronic GVHD), one with stable mixed chimerism. Three patients treated with reduced‐intensity regimens (FLU, BU or CY, ATG, TLI) failed to engraft; one engrafted after second UCBT (HU, TT, RXA, ALZ, TBI). Four patients (57%) developed viral infections. Engraftment, GVHD, and infection remain challenges.

Combination treatment of bullous pemphigoid with anti-CD20 and anti-CD25 antibodies in a patient with chronic graft-versus-host disease.

In this case report we describe a novel treatment with two chimeric monoclonal antibodies (MoAb) targeting the autoimmune B cell clone responsible for bullous pemphigoid (BP) as a manifestation of steroid refractory chronic graft-versus-host disease (GVHD) that developed after unrelated cord blood transplantation. Monitoring the BP-specific circulating antibodies and CD25-expressing activated T lymphocyte subset led us to combine anti-CD20 (Rituximab) mediated B cell ablation with anti-CD25 (Daclizumab) therapy to block CD4+ T cell help. Complete clinical and serologic response was achieved within 4 weeks of initiation of therapy allowing global immunosuppression to be dramatically reduced.

Unrelated umbilical cord blood transplantation and immune reconstitution.

This review highlights the unique features of immune reconstitution following unrelated cord blood transplantation (UCBT) that lead to heightened risk of infection-related mortality in the early post-UCBT period. There is no evidence that innate immunity is uniquely compromised after UCBT, but the development of antigen-specific cellular immunity is affected by numerical and qualitative deficits, primarily within the first 100 days. Nevertheless, beyond the first few months after UCBT there is no evidence for reduced graft-versus-leukemia (GVL) or anti-viral immunity compared to other hematopoietic cell therapy (HCT) modalities. Novel cellular therapies that are about to enter the clinical setting in the form of natural killer (NK) cell and T-cell therapies in the form of donor lymphocyte infusion (DLI) are also discussed.

Bone Marrow Transplantation for Primary Immunodeficiency Diseases

Advances in immunology have led to a breathtaking expansion of recognized primary immunodeficiency diseases (PID) with over 120 disease-related genes identified. In North America alone more than 1000 children have received allogeneic blood or marrow transplant over the past 30 years, with the majority surviving long term. This review presents results and highlights challenges and notable advances, including novel less toxic conditioning regimens, to transplant the more common and severe forms of PID. HLA-matched sibling donors remain the ideal option, however, advances in living donor unrelated HSCT and banked umbilical cord blood grafts provide hope for all children with severe PID.

Posttransplant Autoimmune Hemolytic Anemia and Other Autoimmune Cytopenias are Increased in Very Young Infants Undergoing Unrelated Donor Umbilical Cord Blood Transplantation

Autoimmune cytopenias are a recognized complication of hematopoietic stem cell transplant (HSCT), and are considered to be a feature of chronic graft-versus-host disease (cGVHD). We report on a cohort of very young infants (< or =3 months of age) receiving HSCT from unrelated donor umbilical cord blood for genetic disorders who developed posttransplant autoimmune cytopenias at an increased rate compared to older aged controls. These infants received a conditioning regimen consisting of busulfan, cyclophosphamide, and antithymocyte globulin (ATG). All infants received HLA mismatched unrelated umbilical cord blood as graft source. GVHD prophylaxis was either cyclosporine + methylprednisolone (n = 16) or cyclosporine + mycophenolate mofetil (n = 3). Engraftment, acute GVHD (aGVHD) and cGVHD, survival, treatment-related mortality (TRM), and deaths were evaluated. Ten patients developed cGVHD manifesting as autoimmune cytopenias at a median 247 days posttransplant with a cumulative incidence of 44% (95% confidence interval [CI] 21%-68%) and 56% (95% CI 32%-80%) at 1 and 2 years, respectively. In 6 of 10 patients developing autoimmune cytopenias, cGVHD presented as autoimmune cytopenia de novo. The cytopenias observed included anemia (n = 4), thrombocytopenia (n = 1), anemia with thrombocytopenia (n = 3), and pancytopenia (n = 2). No graft factors were identified as being significant to development of cGVHD. All patients responded to treatment with methylprednisolone, azithioprine +/- rituximab. One patient required splenectomy. We hypothesize that posttransplant immunosuppression interferes with normal immune ontogeny creating immune dysregulation and graft directed cell destruction. Alternative strategies to prevent GVHD should be considered for this unique patient population.

Interleukin-7 Permits Th1/Tc1 Maturation and Promotes Ex vivo Expansion of Cord Blood T Cells: A Critical Step toward Adoptive Immunotherapy after Cord Blood Transplantation

Donor leukocyte infusions (DLI) in the allogeneic hematopoietic transplant setting can provide a clinically relevant boost of immunity to reduce opportunistic infections and to increase graft-versus-leukemia activity. Despite significant advances in applicability, DLI has not been available for single-unit recipients of unrelated cord blood transplant. Ex vivo expansion of cord blood T cells can be achieved with interleukin (IL)-2 and CD3/CD28 costimulatory beads. However, significant apoptosis occurs in proliferating T cells, diminishing the yield and skewing the CD4/CD8 ratio in the T-cell population, jeopardizing the potential efficacy of DLI. In this study, we show that interleukin (IL)-7 not only reduces apoptosis of activated T lymphocytes and enhances their proliferation but also promotes functional maturation, leading to secretion of IFN-gamma and other key cytokines. Recognizing that infused T lymphocytes will need to meet microbial antigens in secondary lymphoid organs to generate effectors, we also show that expansion with IL-7 promotes the preservation of a polyclonal broad T-cell receptor repertoire and a surface phenotype that favors lymph node homing. Expanded lymphocytes lack alloreactivity against recipient and other allogeneic cells, indicating a favorable safety profile from graft-versus-host disease. Nevertheless, expanded T cells can be primed subsequently against lymphoid and myeloid leukemia cells to generate tumor-specific cytotoxic T cells. Taken together, our findings offer a major step in fulfilling critical numerical and biological requirements to quickly generate a DLI product ex vivo using a negligible fraction of a cord blood graft that provides a flexible adoptive immunotherapy platform for both children and adults.

A novel reduced-intensity conditioning regimen for unrelated umbilical cord blood transplantation in children with nonmalignant diseases.

Reduced-intensity conditioning (RIC) regimens have the potential to decrease transplantation-related morbidity and mortality. However, engraftment failure has been prohibitively high after RIC unrelated umbilical cord blood transplantation (UCBT) in chemotherapy-naïve children with nonmalignant diseases (NMD). Twenty-two children with a median age of 2.8 years, many with severe comorbidities and prior viral infections, were enrolled in a novel RIC protocol consisting of hydroxyurea, alemtuzumab, fludarabine, melphalan, and thiotepa followed by single UCBT. Patients underwent transplantation for inherited metabolic disorders (n = 8), primary immunodeficiencies (n = 9), hemoglobinopathies (n = 4) and Diamond Blackfan anemia (n = 1). Most umbilical cord blood (UCB) units were HLA-mismatched with median infused total nucleated cell dose of 7.9 × 10(7)/kg. No serious organ toxicities were attributable to the regimen. The cumulative incidence of neutrophil engraftment was 86.4% (95% confidence interval [CI], 65% to 100%) in a median of 20 days, with the majority sustaining > 95% donor chimerism at 1 year. Cumulative incidence of acute graft-versus-host disease (GVHD) grades II to IV and III to IV by day 180 was 27.3% (95% CI, 8.7% to 45.9%) and 13.6% (95 CI, 0% to 27.6%), respectively. Cumulative incidence of extensive chronic GVHD was 9.1% (95% CI, 0% to 20.8%). The primary causes of death were viral infections (n = 3), acute GVHD (n = 1) and transfusion reaction (n = 1). One-year overall and event-free survivals were 77.3% (95% CI, 53.7% to 89.8%) and 68.2% (95% CI, 44.6% to 83.4%) with 31 months median follow-up. This is the first RIC protocol demonstrating durable UCB engraftment in children with NMD. Future risk-based modifications of this regimen could decrease the incidence of viral infections. (www.clinicaltrials.gov/NCT00744692).