Granulocyte Transfusions: A Critical Reappraisal

Comparison of two apheresis systems for granulocyte collection without hydroxyethyl starch

BACKGROUND AND OBJECTIVES

Granulocyte transfusion (GTX) is a treatment option for severe infections in patients with neutropenia. In previous studies, hydroxyethyl starch (HES) was used to enhance red blood cell sedimentation for granulocyte collection (GC). However, there are safety concerns about HES, and HES is not readily available in some countries. Therefore, we compared the granulocyte counts and GC efficiency achieved by two apheresis systems without HES.

MATERIALS AND METHODS

All consecutive GC procedures performed between July 2011 and March 2018 at our hospital were analysed. COBE Spectra was used until 5 February 2016, and Spectra Optia was used afterwards. HES was not used.

RESULTS

Twenty-six GC procedures were performed, including 18 performed using COBE Spectra and 8 using Spectra Optia. When Spectra Optia was used, >1 × 1010 neutrophils were collected from seven of the eight (88%) procedures. Although there was no significant difference in the granulocyte yield between COBE Spectra-based and Spectra Optia-based GC procedures, the collection efficiency of Spectra Optia was significantly higher than that of COBE Spectra (p = 0.021). Furthermore, the granulocyte yields of Spectra Optia-based GC tended to be more strongly correlated with the peripheral blood neutrophil count on the day of apheresis than those of COBE Spectra-based GC.

CONCLUSION

Our results suggest that Spectra Optia achieves greater GC efficiency than COBE Spectra, even without HES. GTX may be a therapeutic option for severe neutropenia, even in places where HES is not available.

Transfusion support in hematopoietic stem cell transplantation

Transfusion support for hematopoietic stem cell transplantation (HSCT) is an essential part of supportive care, and compatible blood should be transfused into recipients. As leukocyte antigen (HLA) matching is considered first and as the blood group does not impede HSCT, major, minor, bidirectional, and RhD incompatibilities occur that might hinder transfusion and cause adverse events. Leukocyte reduction in blood products is frequently used, and irradiation should be performed for blood products, except for plasma. To mitigate incompatibility and adverse events, local transfusion guidelines, hospital transfusion committees, and patient management should be considered.

Risk stratification by 30-day prognostic factors of clinical outcomes after granulocyte transfusion in acute myeloid leukemia: A single-center retrospective study

Background

Granulocyte transfusions (GTs) have been used to treat infections in neutropenic patients undergoing chemotherapy or hematopoietic stem cell transplantation. However, there is persistent controversy regarding their outcomes. We aimed to analyze accumulated clinical and laboratory data from patients with acute myeloid leukemia (AML) who underwent GT at our institution in the last 10 years to determine optimal parameters to estimate the GT effect. We hypothesized that patients grouped according to prognostic factors would have inconsistent clinical outcomes.

Materials and methods

In this single-center retrospective study, we collected medical records of 219 GT-treated patients diagnosed with AML from 2009 to 2019. Prognostic factors, including clinical and laboratory parameters, were assessed. Serial measurements of laboratory parameters before and after GT were collected, and the area under the curve of the white blood cells (AUC-WBC) was calculated using the trapezoidal method. A prognostic scoring system using 8 factors from multivariate analysis was analyzed. The primary outcome was survival at 30 days (D30) after GT initiation.

Results

The 8 factors for the prognosis scoring system included secondary AML, mean AUC-WBC, prothrombin time, and levels of blood urea nitrogen (BUN), bilirubin, alanine aminotransferase (ALT), phosphorus, and lactate dehydrogenase (LDH). Patients were grouped into 4 risk groups (low, medium, high, and very high), and the D30 survival rates for each group were as follows: 87.6% (99/113), 55.9% (33/59), 21.1% (4/19), and 0% (0/19), respectively. Hematopoiesis, liver, and renal function affected the outcome. FLT3 mutation acted as a favorable factor for D30 survival.

Conclusions

GT response in patients with AML seemed to be reflected by 8 score markers, and GT was significantly effective in the low-risk group. We suggest that it is important to evaluate the risk assessment of patients before GT to achieve better outcomes.

Impact of the use of hydroxyethyl starch in granulocyte apheresis using Spectra Optia

OBJECTIVES

To determine the impact of the use of hydroxyethyl starch (HES) in granulocyte apheresis using Spectra Optia.

BACKGROUND

Granulocyte transfusion (GT) is a therapeutic option for neutropenic patients with severe bacterial or fungal infections. Recent studies in emergency medicine have shown the potential risk of using HES, which is routinely used in granulocyte apheresis to increase yield by sedimenting red blood cells. We hypothesized that the use of a newer device (Spectra Optia) would spare the need for HES.

METHODS

We retrospectively compared granulocyte apheresis with HES (HES group, n = 89) and without HES (non-HES group, n = 36) using Spectra Optia.

RESULTS

The granulocyte yield was significantly higher in the HES group (7.3 × 10¹⁰ vs. 2.0 × 10, p < 0.01) and was attributed to the difference in collection efficiency (36% vs. 7.7%, p < 0.01). The absolute neutrophil count on the following morning of GT was significantly higher in the HES group than in the non-HES group (2460/μl vs. 505/μl, p < 0.01). There were no significant differences in the occurrence of adverse events between the HES and non-HES groups. The renal function was unchanged in both groups after apheresis.

CONCLUSIONS

We demonstrated that the advantage of using HES remained unchanged in granulocyte apheresis using Spectra Optia.

Cord blood CD8+ T-cell expansion following granulocyte transfusions eradicates refractory leukemia

The action of hematopoietic cell transplantation in controlling leukemia is principally mediated by donor T cells directed against residual recipient malignant cells. However, its utility is limited by graft-versus-host disease (GVHD), where alloreactivity is extended beyond leukemic and marrow cells. In a human/murine chimeric model, we previously showed that the preferential infiltration of cord blood (CB) CD8+ T cells eradicates an Epstein-Barr virus-driven lymphoblastoid tumor without causing xenogeneic GVHD. In the clinic, however, cord blood CD8+ T-cell reconstitution is significantly delayed, and the observation of such a robust antileukemia effect mediated by cord blood CD8+ T cells has not been reported. We describe an observation of very early T-cell expansion in 4 high-risk pediatric leukemia patients receiving third-party, pooled granulocytes after T cell-replete CB transplantation (CBT). The T-cell expansion was transient but robust, including expansion of CD8+ T cells, in contrast to the delayed CD8+ T-cell expansion ordinarily observed after T cell-replete CBT. The CD8+ T cells were polyclonal, rapidly switched to memory phenotype, and had the ability to mediate cytotoxicity. This phenomenon is reproducible, and each patient remains in long-term remission without GVHD. The results suggest that fetal-derived CB CD8+ T cells can be exploited to generate robust antileukemia effects without GVHD.

Effective and Rapid Generation of Functional Neutrophils from Induced Pluripotent Stem Cells Using ETV2-Modified mRNA

Human induced pluripotent stem cells (hiPSCs) can serve as a versatile and scalable source of neutrophils for biomedical research and transfusion therapies. Here we describe a rapid efficient serum- and xenogen-free protocol for neutrophil generation, which is based on direct hematoendothelial programming of hiPSCs using ETV2-modified mRNA. Culture of ETV2-induced hematoendothelial progenitors in the presence of GM-CSF, FGF2, and UM171 led to continuous production of generous amounts of CD34⁺CD33⁺ myeloid progenitors which could be harvested every 8–10 days for up to 30 days of culture. Subsequently, myeloid progenitors were differentiated into neutrophils in the presence of G-CSF and the retinoic acid agonist Am580. Neutrophils obtained in these conditions displayed a typical somatic neutrophil morphology, produced reactive oxygen species, formed neutrophil extracellular traps and possessed phagocytic and chemotactic activities. Overall, this technology offers an opportunity to generate a significant number of neutrophils as soon as 14 days after initiation of differentiation.

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ETV2 mmRNA directly programs hPSCs into hemogenic endothelium (HE)

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ETV2-induced HE possesses robust myeloid potential

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ETV2 mmRNA rapid neutrophil differentiation protocol in defined conditions is provided

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ETV2 mmRNA-induced neutrophils are functionally similar to in-vivo-derived cells

Review of current transfusion therapy and blood banking practices

Transfusion Medicine is a dynamically evolving field. Recent high-quality research has reshaped the paradigms guiding blood transfusion. As increasing evidence supports the benefit of limiting transfusion, guidelines have been developed and disseminated into clinical practice governing optimal transfusion of red cells, platelets, plasma and cryoprecipitate. Concepts ranging from transfusion thresholds to prophylactic use to maximal storage time are addressed in guidelines. Patient blood management programs have developed to implement principles of patient safety through limiting transfusion in clinical practice. Data from National Hemovigilance Surveys showing dramatic declines in blood utilization over the past decade demonstrate the practical uptake of current principles guiding patient safety. In parallel with decreasing use of traditional blood products, the development of new technologies for blood transfusion such as freeze drying and cold storage has accelerated. Approaches to policy decision making to augment blood safety have also changed. Drivers of these changes include a deeper understanding of emerging threats and adverse events based on hemovigilance, and an increasing healthcare system expectation to align blood safety decision making with approaches used in other healthcare disciplines.

Acute respiratory failure and the kinetics of neutrophil recovery in pediatric hematopoietic cell transplantation: a multicenter study

In this multicenter study, we investigated the kinetics of neutrophil recovery in relation to acuity and survival among 125 children undergoing allogeneic hematopoietic cell transplantation (allo-HCT) who required invasive mechanical ventilation (IMV). Recovery of neutrophils, whether prior to or after initiation of IMV, was associated with a significantly decreased risk of death relative to never achieving neutrophil recovery. A transient increase in acuity (by oxygenation index and vasopressor requirements) occurred among a subset of the patients who achieved neutrophil recovery after initiation of IMV; 61.5% of these patients survived to discharge from the intensive care unit (ICU). Improved survival among patients who subsequently achieved neutrophil recovery on IMV was not limited to those with peri-engraftment respiratory distress syndrome. The presence of a respiratory pathogen did not affect the risk of death while on IMV but was associated with an increased length of IMV (p < 0.01). Among patients undergoing HCT who develop respiratory failure and require advanced therapeutic support, neutrophil recovery at time of IMV and/or presence of a respiratory pathogen should not be used as determining factors when counseling families about survival.

Role of granulocyte transfusions in combating life-threatening infections in patients with severe neutropenia: Experience from a tertiary care centre in North India

Bacterial and fungal infections still remain an important cause of mortality in patients with hematological malignancies and in recipients of hematopoietic stem cell transplants (HSCT) especially in developing countries like India. Granulocyte transfusions (GTX) from healthy donors may lead to early clearance of index infection and thus prevent mortality. The aim of the present study was to evaluate the efficacy of GTX in combating life-threatening infections and preventing mortality in patients of hematological disorders/recipients of HSCT with severe neutropenia. This study was a prospective, observational analysis of patients with different hematological disorders/recipients of HSCT, who received GTX from January 2014 to December 2017. All patients had an Absolute neutrophil Count (ANC) < 0.5 x 109/L and a life threatening sepsis defined by presence of hemodynamic instability/ impending septic shock/ continuous high fever despite the use of the highest line of antimicrobials. A total of 143 granulocyte collections were done for 66 infectious episodes (IEs) in 60 patients. Multidrug resistant organisms (MDROs) were observed in 47/66 IEs (71.2%) and fungal infections were seen in 9/66 IEs (13.6%). Resolution of index infection after GTX was seen in 45/66 IEs (68.2%), and the 30 day overall survival (OS) was 67.7%. OS was significantly higher in patients who received GTX within 7 days of neutropenic sepsis (p = 0.01). Patients with MDROs who received early GTX therapy had a better OS as compared to those who received late GTX (p = 0.02). GTX were well tolerated and only 6 patients' developed mild features of transfusion related acute lung injury (TRALI) which was managed conservatively, and 1 patient demonstrated hypocalcemic tetany. GTX may be of particular relevance in countries like India, where the incidence of infections is very high in neutropenic patients and there is an increasing emergence of MDROs.

Immunomodulation as Therapy for Fungal Infection: Are We Closer?

Invasive fungal disease (IFD) causes significant morbidity in immunocompromised patients due to their weakened immune system. Immunomodulatory therapy, in synergy with existing antifungal therapy, is an attractive option to enhance their immune system and aid clearance of these opportunistic pathogens. From a scientific and clinical perspective, we explore the immunotherapeutic options to augment standard antifungal drugs for patients with an IFD. We discuss the range of immunomodulatory therapies being considered in IFD - from cytokines, including G-CSF, GM-CSF, M-CSF, IFN-γ, and cytokine agonists, to cellular therapies, consisting of granulocyte transfusion, adoptive T-cell, CAR T-cell, natural killer cell therapies, and monoclonal antibodies. Adjunct pharmaceutical agents which augment the immunity are also being considered. Lastly, we explore the likelihood of the use of probiotics and manipulation of the microbiome/mycobiome to enhance IFD treatment outcomes.

Methods of Controlling Invasive Fungal Infections Using CD8+ T Cells

Invasive fungal infections (IFIs) cause high rates of morbidity and mortality in immunocompromised patients. Pattern-recognition receptors present on the surfaces of innate immune cells recognize fungal pathogens and activate the first line of defense against fungal infection. The second line of defense is the adaptive immune system which involves mainly CD4+ T cells, while CD8+ T cells also play a role. CD8+ T cell-based vaccines designed to prevent IFIs are currently being investigated in clinical trials, their use could play an especially important role in acquired immune deficiency syndrome patients. So far, none of the vaccines used to treat IFI have been approved by the FDA. Here, we review current and future antifungal immunotherapy strategies involving CD8+ T cells. We highlight recent advances in the use of T cells engineered using a Sleeping Beauty vector to treat IFIs. Recent clinical trials using chimeric antigen receptor (CAR) T-cell therapy to treat patients with leukemia have shown very promising results. We hypothesized that CAR T cells could also be used to control IFI. Therefore, we designed a CAR that targets β-glucan, a sugar molecule found in most of the fungal cell walls, using the extracellular domain of Dectin-1, which binds to β-glucan. Mice treated with D-CAR+ T cells displayed reductions in hyphal growth of Aspergillus compared to the untreated group. Patients suffering from IFIs due to primary immunodeficiency, secondary immunodeficiency (e.g., HIV), or hematopoietic transplant patients may benefit from bioengineered CAR T cell therapy.