Successful treatment of an infant with CDA type II by intrauterine transfusions and postnatal stem cell transplantation

Congenital dyserythropoietic anemias are rare hematological disorders leading to ineffective erythropoiesis with chronic anemia, complicated by iron overload. Here we present a remarkable clinical course of an infant with CDA type II who first presented as a severe fetal hydrops, requiring serial intrauterine red cell transfusions. While postnatal transfusion dependency persisted, the patient was successfully transplanted with a myeloablative conditioning regimen and peripheral blood stem cells of a matched donor. We believe that allogeneic HSCT is a reasonable therapeutic approach for patients with very severe CDA, even if only a matched unrelated donor is available.

Transferred WT1-reactive CD8+ T cells can mediate antileukemic activity and persist in post-transplant patients

Relapse remains a leading cause of death after allogeneic hematopoietic cell transplantation (HCT) for patients with high-risk leukemias. The potentially beneficial donor T cell-mediated graft-versus-leukemia (GVL) effect is often mitigated by concurrent graft-versus-host disease (GVHD). Providing T cells that can selectively target Wilms tumor antigen 1 (WT1), a transcription factor overexpressed in leukemias that contributes to the malignant phenotype, represents an opportunity to promote antileukemic activity without inducing GVHD. HLA-A*0201-restricted WT1-specific donor-derived CD8 cytotoxic T cell (CTL) clones were administered after HCT to 11 relapsed or high-risk leukemia patients without evidence of on-target toxicity. The last four treated patients received CTL clones generated with exposure to interleukin-21 (IL-21) to prolong in vivo CTL survival, because IL-21 can limit terminal differentiation of antigen-specific T cells generated in vitro. Transferred cells exhibited direct evidence of antileukemic activity in two patients: a transient response in one patient with advanced progressive disease and the induction of a prolonged remission in a patient with minimal residual disease (MRD). Additionally, three treated patients at high risk for relapse after HCT survive without leukemia relapse, GVHD, or additional antileukemic treatment. CTLs generated in the presence of IL-21, which were transferred in these latter three patients and the patient with MRD, all remained detectable long-term and maintained or acquired in vivo phenotypic and functional characteristics associated with long-lived memory CD8 T cells. This study supports expanding efforts to immunologically target WT1 and provides insights into the requirements necessary to establish potent persistent T cell responses.

Gangliosides inhibit the development from monocytes to dendritic cells

Dendritic cell (DC) development and function is critical in the initiation phase of any antigen-specific immune response against tumours. Impaired function of DC is one explanation as to how tumours escape immunosurveillance. In the presence of various soluble tumour-related factors DC precursors lose their ability to differentiate into mature DC and to activate T cells. Gangliosides are glycosphingolipids shed by tumours of neuroectodermal origin such as melanoma and neuroblastoma. In this investigation we address the question of whether gangliosides suppress the development and function of monocyte-derived DC in vitro. In the presence of gangliosides, the monocytic DC precursors showed increased adherence, cell spreading and a reduced number of dendrites. The expression of MHC class II molecules, co-stimulatory molecules and the GM-CSF receptor (CD116) on the ganglioside-treated DC was significantly reduced. Furthermore, the function of ganglioside-treated DC was impaired as observed in endocytosis, chemotactic and T cell proliferation assays. In contrast to monocytic DC precursors, mature DC were unaffected even when higher doses of gangliosides were added to the culture. With regard to their carbohydrate structure, five different gangliosides (GM2, GM3, GD2, GD3, GT1b), which are typically shed by melanoma and neuroblastoma, were tested for their ability to suppress DC development and function. Suppression was induced by GM2, but not by the other gangliosides. These data suggest that certain gangliosides impair DC precursors, implying a possible mechanism for tumour escape.

Induction of tolerance by IL-10-treated dendritic cells

Dendritic cells (DC) form a specialized system for presenting Ag to naive or quiescent T cells and consequently play a central role in the induction of T and B cell immunity. In this study we used DC generated from peripheral progenitors to analyze the effect of IL-10 on the accessory function of human DC. We demonstrate that immature DC, harvested on days 9 to 11 and exposed to IL-10 for the last 2 days of culture, show a strongly reduced capacity to stimulate a CD4+ T cell response in an allogeneic MLR in a dose-dependent manner. In contrast, fully mature DC are completely resistant to the effects of IL-10. These results were obtained in both an alloantigen-induced MLR and an anti-CD3 mAb-induced response of primed and naive (CD45RA+) CD4+ T cells. FACS analysis revealed inhibition of the up-regulation of the costimulatory molecules CD58 and CD86 and the specific DC marker CD83 in DC pretreated with IL-10. These data suggest that IL-10 inhibited the development of fully mature DC. Furthermore, DC precultured with IL-10, but not controls, induced a state of alloantigen-specific anergy in CD4+ T cells and of peptide-specific anergy in the influenza hemagglutinin-specific T cell clone HA1.7. Analysis of the supernatants of these anergic T cells revealed a reduced production of IL-2 and IFN-gamma compared with that in control cells. Collectively, these data suggest that IL-10 converts immature DC into tolerogenic APC, which might be a useful tool in the therapy of patients with autoimmune or allergic diseases.

Induction of tolerance by IL-10-treated dendritic cells

Dendritic cells (DC) form a specialized system for presenting Ag to naive or quiescent T cells and consequently play a central role in the induction of T and B cell immunity. In this study we used DC generated from peripheral progenitors to analyze the effect of IL-10 on the accessory function of human DC. We demonstrate that immature DC, harvested on days 9 to 11 and exposed to IL-10 for the last 2 days of culture, show a strongly reduced capacity to stimulate a CD4+ T cell response in an allogeneic MLR in a dose-dependent manner. In contrast, fully mature DC are completely resistant to the effects of IL-10. These results were obtained in both an alloantigen-induced MLR and an anti-CD3 mAb-induced response of primed and naive (CD45RA+) CD4+ T cells. FACS analysis revealed inhibition of the up-regulation of the costimulatory molecules CD58 and CD86 and the specific DC marker CD83 in DC pretreated with IL-10. These data suggest that IL-10 inhibited the development of fully mature DC. Furthermore, DC precultured with IL-10, but not controls, induced a state of alloantigen-specific anergy in CD4+ T cells and of peptide-specific anergy in the influenza hemagglutinin-specific T cell clone HA1.7. Analysis of the supernatants of these anergic T cells revealed a reduced production of IL-2 and IFN-gamma compared with that in control cells. Collectively, these data suggest that IL-10 converts immature DC into tolerogenic APC, which might be a useful tool in the therapy of patients with autoimmune or allergic diseases.