Donor chimerism and immune reconstitution following haploidentical transplantation in sickle cell disease

Introduction

We previously reported the initial results of a phase II multicenter transplant trial using haploidentical parental donors for children and aolescents with high-risk sickle cell disease achieving excellent survival with exceptionally low rates of graft-versus-host disease and resolution of sickle cell disease symptoms. To investigate human leukocyte antigen (HLA) sensitization, graft characteristics, donor chimerism, and immune reconstitution in these recipients.

Methods

CD34 cells were enriched using the CliniMACS^® system with a target dose of 10 x 10⁶ CD34⁺ cells/kg with a peripheral blood mononuclear cell (PBMNC) addback dose of 2x10⁵ CD3/kg in the final product. Pre-transplant HLA antibodies were characterized. Donor chimerism was monitored 1-24 months post-transplant. Comprehensive assessment of immune reconstitution included lymphocyte subsets, plasma cytokines, complement levels, anti-viral T-cell responses, activation markers, and cytokine production. Infections were monitored.

Results

HLA antibodies were detected in 7 of 11 (64%) evaluable patients but rarely were against donor antigens. Myeloid engraftment was rapid (100%) at a median of 9 days. At 30 days, donor chimerism was 93-99% and natural killer cell levels were restored. By 60 days, CD19 B cells were normal. CD8 and CD4 T-cells levels were normal by 279 and 365 days, respectively. Activated CD4 and CD8 T-cells were elevated at 100-365 days post-transplant while naïve cells remained below baseline. Tregs were elevated at 100-270 days post-transplant, returning to baseline levels at one year. At one year, C3 and C4 levels were above baseline and CH50 levels were near baseline. At one year, cytokine levels were not significantly different from baseline.

Discussion

These results suggest that haploidentical transplantation with CD34-enriched cells and peripheral blood mononuclear cell addback results in rapid engraftment, sustained donor chimerism and broad-based immune reconstitution.

A Pilot Study of RNA Sequencing to Improve the Diagnostic Yield of Bronchoalveolar Lavage Specimens in Pediatric Allogeneic Hematopoietic Stem Cell Transplant Recipients

BACKGROUND

Pulmonary complications often cause morbidity and mortality in pediatric allogeneic hematopoietic stem cell transplant (HSCT) recipients. While detection of infection and initiation of appropriate antimicrobial therapy improves survival, present techniques oftentimes do not detect infections in bronchoalveolar lavage (BAL) samples because of pretreatment with antimicrobial therapies and the need for a priori knowledge of likely viral pathogens, decreasing the yield of BAL.

OBJECTIVE

We evaluated whether RNA-based massively parallel sequencing (MPS) would improve detection of infections in BAL fluid in pediatric allogeneic HSCT recipients.

RESULTS

Nine patients underwent 10 BAL (1 patient underwent 2 BAL) and had sufficient BAL fluid for inclusion in this study. Clinical microbiological testing identified infections in 7 patients, and MPS identified infections in 5 patients, although some of these detected organisms were not detected by clinical testing. Results were fully concordant in 5 patients, fully discordant in 3 patients, and partially discordant in 2 patients. Bacterial, viral, and fungal infections were detected via both techniques.

CONCLUSION

This suggests that MPS in conjunction with routine clinical testing increases the yield of detection of infectious organisms in the BAL fluid.

Current Studies of Immunotherapy on Glioblastoma

Glioblastoma is a form of brain tumor with a very high morbidity and mortality. Despite decades of research, the best treatments currently in clinical practice only extend survival by a number of months. A promising alternative to conventional treatment for glioblastomas is immunotherapy. Although proposed over a century ago, the field of cancer immunotherapy has historically struggled to translate it into effective clinical treatments. Better understanding is needed of the various regulatory and co-stimulatory factors in the glioblastoma patient for more efficient immunotherapy treatments. The tumor microenvironment is anatomically shielded from normal immune-surveillance by the blood-brain barrier, irregular lymphatic drainage system, and it's in a potently immunosuppressive environment. Immunotherapy can potentially manipulate these forces effectively to enhance anti-tumor immune response and clinical benefit. New treatments utilizing the immune system show promise in terms of targeting and efficacy. This review article attempts to discuss current practices in glioblastoma treatment, the theory behind immunotherapy, and current research into various clinical trials.