Prolonging neutrophil room-temperature storage with clinically approved solutions: implications for granulocyte transfusion

Granulocyte concentrates (GCs) are leukocyte preparations enriched in neutrophils that can potentially save neutropenic patients from life-threatening, antimicrobial-resistant infections. The main challenge of GC transfusions is preserving the viability and antimicrobial activity of neutrophils beyond 24 h to reduce the logistical burden on collection centers and increase the availability of this cell therapy. Thus, the aim of this study was to explore extending the ex vivo viability and antimicrobial activity of GC neutrophils up to 72 h with a unique combination of the clinically approved additives Plasma-Lyte (PL), SAGM, AS-3, and Alburex. Neutrophils isolated from healthy donors were resuspended in autologous plasma at the same concentration as in GCs, diluted with various combinations of PL, SAGM, AS-3, and/or Alburex with or without the addition of buffers, and stored at room temperature for up to 72 h. During storage, neutrophil viability, phagocytosis, and intracellular reactive oxygen species production were measured by flow cytometry. Extracellular reactive oxygen species production was measured by spectrophotometry and chemotaxis by the number of calcein-stained neutrophils that migrated toward the chemotactic peptide, N-formyl-Met-Leu-Phe (fMLF). The same assays were performed on pooled, residual leukocyte units generated by the Reveos system, after storage in the additive combination that most effectively preserved the viability and function of isolated neutrophils. The additive combination that best performed in the majority of the assays contained PL, buffers, and AS-3. Neutrophil viability was preserved for a maximum of 48 h and phagocytosis of opsonized bacteria and reactive oxygen species production up to 72 h of storage at room temperature. In contrast, fMLF-induced chemotaxis decreased by 20% after 24-h storage while extracellular reactive oxygen species production increased significantly within the same time period. Supplementing GCs prepared from pooled, residual leukocyte units with this storage solution after the standard 16- to 24-h processing period as per the blood center guidelines, did not significantly improve the preservation of neutrophil viability and function. Our findings provide proof of concept that mixtures of clinically approved additives can be tailored to significantly prolong the viability and function of freshly isolated neutrophils during room-temperature storage. The unique additive composition of this storage solution that we developed for freshly isolated neutrophils requires further optimization for use with pooled, residual leukocyte units as well as the timepoint at which the solution is added during processing to prolong the viability and functions of neutrophils in this blood product.

Activated neutrophils: A next generation cellular immunotherapy

Cell therapies are at the forefront of novel therapeutics. Neutrophils, despite being the most populous immune cells in human blood circulation, are not considered a viable option for cellular therapies because of their short lifespan and poor understanding of their role in the pathophysiology of various diseases. In inflammatory conditions, neutrophils exhibit an activated phenotype. Activation brings about significant changes to neutrophil biology such as increased lifespan, inflammatory cytokine secretion, and enhanced effector functions. Activated neutrophils also possess the potential to stimulate the downstream immune response and are described as essential effectors in the immune response to tumors. This makes activated neutrophils an interesting candidate for cell therapies. Here, we review the biology of activated neutrophils in detail. We discuss the different ways neutrophils can be activated and the effect they have on other immune cells for stimulation of downstream immune response. We review the conditions where activated neutrophil therapy can be therapeutically beneficial and discuss the challenges associated with their eventual translation. Overall, this review summarizes the current state of understanding of neutrophil-based immunotherapies and their clinical potential.

Neutrophil Granulopoiesis Optimized Through Ex Vivo Expansion of Hematopoietic Progenitors in Engineered 3D Gelatin Methacrylate Hydrogels

Neutrophils are the first line of defense of the innate immune system. In response to methicillin-resistant Staphylococcus aureus infection in the skin, hematopoietic stem, and progenitor cells (HSPCs) traffic to wounds and undergo extramedullary granulopoiesis, producing neutrophils necessary to resolve the infection. This prompted the engineering of a gelatin methacrylate (GelMA) hydrogel that encapsulates HSPCs within a matrix amenable to subcutaneous delivery. The authors study the influence of hydrogel mechanical properties to produce an artificial niche for granulocyte-monocyte progenitors (GMPs) to efficiently expand into functional neutrophils that can populate infected tissue. Lin-cKIT+ HSPCs, harvested from fluorescent neutrophil reporter mice, are encapsulated in GelMA hydrogels of varying polymer concentration and UV-crosslinked to produce HSPC-laden gels of specific stiffness and mesh sizes. Softer 5% GelMA gels yield the most viable progenitors and effective cell-matrix interactions. Compared to suspension culture, 5% GelMA results in a twofold expansion of mature neutrophils that retain antimicrobial functions including degranulation, phagocytosis, and ROS production. When implanted dermally in C57BL/6J mice, luciferase-expressing neutrophils expanded in GelMA hydrogels are visualized at the site of implantation for over 5 days. They demonstrate the potential of GelMA hydrogels for delivering HSPCs directly to the site of skin infection to promote local granulopoiesis.

Harnessing bioengineered myeloid progenitors for precision immunotherapies

Granulocytes and macrophages are the frontline defenders of the innate immune system. These myeloid cells play a crucial role in not only eliminating pathogens and tumor cells, but also regulating adaptive immune responses. In neonatal sepsis and post-chemotherapy agranulocytosis, the absence of these cells leaves the host highly vulnerable to infections. Beyond replacement to prevent or control neutropenic sepsis, engineered myeloid cells may offer distinct opportunities for cell therapies. For example, the mobility and specific homing capacities of neutrophils to sites of inflammation could be exploited to deliver biocidal agents, or anti-inflammatory healing signals during sepsis, autoimmunity, and organ transplantation. Additionally, myeloid cells can be engineered to express chimeric antigen receptors (CAR), carry chemotherapeutics, or enhance lymphoid tumor killing. However, traditional methods of cell isolation are incapable of providing sufficient cell numbers of these short-lived cells; their propensity for premature activation further complicates their cell engineering. Here, we review current and future biotherapeutic innovations that employ engineered multipotent myeloid progenitors derived from either self-renewing human induced pluripotent stem cells (hiPSC) or primary CD34+ hematopoietic stem-progenitors. We provide a roadmap for solving the challenges of sourcing, cost, and production of engineered myeloid cell therapies.

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.

Dissecting the process of human neutrophil lineage determination by using alpha-lipoic acid inducing neutrophil deficiency model

Granulocyte-monocyte progenitors (GMPs) differentiate into both neutrophils and monocytes. Recently, uni-potential neutrophil progenitors have been identified both in mice and humans using an array of surface markers. However, how human GMPs commit to neutrophil progenitors and the regulatory mechanisms of fate determination remain incompletely understood. In the present study, we established a human neutrophil deficiency model using the small molecule alpha-lipoic acid. Using this neutrophil deficiency model, we determined that the neutrophil progenitor commitment process from CD371⁺ CD115^– GMPs defined by CD34 and CD15 and discovered that critical signals generated by RNA splicing and rRNA biogenesis regulate the process of early commitment for human early neutrophil progenitors derived from CD371⁺ CD115^– GMPs. These processes were elucidated by single-cell RNA sequencing both in vitro and in vivo derived cells. Sequentially, we identified that the transcription factor ELK1 is essential for human neutrophil lineage commitment using the alpha-lipoic acid (ALA)-inducing neutrophil deficiency model. Finally, we also revealed differential roles for long-ELK1 and short-ELK1, balanced by SF3B1, in the commitment process of neutrophil progenitors. Taken together, we discovered a novel function of ALA in regulating neutrophil lineage specification and identified that the SF3B1-ELK axis regulates the commitment of human neutrophil progenitors from CD371⁺ CD115^– GMPs.

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ALA completely blocks the differentiation of human neutrophils derived from CD34⁺ stem cells in ex-vivo culture.

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CD34 and CD15 could be used to define the early differentiation stages of human neutrophil lineage determination.

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SF3B1-ELK1 signal axis regulates human neutrophil lineage determination.

Engraftment, Fate, and Function of HoxB8-Conditional Neutrophil Progenitors in the Unconditioned Murine Host

The development and use of murine myeloid progenitor cell lines that are conditionally immortalized through expression of HoxB8 has provided a valuable tool for studies of neutrophil biology. Recent work has extended the utility of HoxB8-conditional progenitors to the in vivo setting via their transplantation into irradiated mice. Here, we describe the isolation of HoxB8-conditional progenitor cell lines that are unique in their ability to engraft in the naïve host in the absence of conditioning of the hematopoietic niche. Our results indicate that HoxB8-conditional progenitors engraft in a β1 integrin-dependent manner and transiently generate donor-derived mature neutrophils. Furthermore, we show that neutrophils derived in vivo from transplanted HoxB8-conditional progenitors are mobilized to the periphery and recruited to sites of inflammation in a manner that depends on the C-X-C chemokine receptor 2 and β2 integrins, the same mechanisms that have been described for recruitment of endogenous primary neutrophils. Together, our studies advance the understanding of HoxB8-conditional neutrophil progenitors and describe an innovative tool that, by virtue of its ability to engraft in the naïve host, will facilitate mechanistic in vivo experimentation on neutrophils.

Targeting multiple cell death pathways extends the shelf life and preserves the function of human and mouse neutrophils for transfusion

Clinical outcomes from granulocyte transfusion (GTX) are disadvantaged by the short shelf life and compromised function of donor neutrophils. Spontaneous neutrophil death is heterogeneous and mediated by multiple pathways. Leveraging mechanistic knowledge and pharmacological screening, we identified a combined treatment, caspases-lysosomal membrane permeabilization-oxidant-necroptosis inhibition plus granulocyte colony-stimulating factor (CLON-G), which altered neutrophil fate by simultaneously targeting multiple cell death pathways. CLON-G prolonged human and mouse neutrophil half-life in vitro from less than 1 day to greater than 5 days. CLON-G-treated aged neutrophils had equivalent morphology and function to fresh neutrophils, with no impairment to critical effector functions including phagocytosis, bacterial killing, chemotaxis, and reactive oxygen species production. Transfusion with stored CLON-G-treated 3-day-old neutrophils enhanced host defenses, alleviated infection-induced tissue damage, and prolonged survival as effectively as transfusion with fresh neutrophils in a clinically relevant murine GTX model of neutropenia-related bacterial pneumonia and systemic candidiasis. Last, CLON-G treatment prolonged the shelf life and preserved the function of apheresis-collected human GTX products both ex vivo and in vivo in immunodeficient mice. Thus, CLON-G treatment represents an effective and applicable clinical procedure for the storage and application of neutrophils in transfusion medicine, providing a therapeutic strategy for improving GTX efficacy.

Granulocyte concentrates prepared from residual leukocyte units produced by the Reveos automated blood processing system

BACKGROUND

Granulocyte concentrates are mainly derived by apheresis technique from donors stimulated with granulocyte colony-stimulating factor and steroids. The automated blood processing system Reveos, which is now increasingly used across the world, separates whole blood into four components, including a residual leukocyte unit containing granulocytes. The aim of this study was to produce an alternative granulocyte concentrate from leukocyte units produced by the Reveos system, and to assess the function of the granulocytes.

METHODS

The number of granulocytes was measured in residual leukocyte units, derived from whole blood donations, with different volumes ranging from 10 to 40 ml. After deciding the optimal volume of the leukocyte unit (30 ml), ten ABO-matched units were pooled to form a granulocyte concentrate. The function of the granulocytes from residual leukocyte units was assessed by analyzing surface markers, phagocytosis of yeast, and production of reactive oxygen species.

RESULTS

Residual leukocyte units with a volume of 30 ml contained a median number of 0,7 × 10⁹ granulocytes, and granulocyte concentrates prepared from ten pooled 30 ml-leukocyte units contained a median number of 6,3 × 10⁹ granulocytes. Granulocytes derived from residual leukocyte units displayed surface markers associated with granulocyte function, and capability to phagocytose yeast and produce reactive oxygen species.

CONCLUSIONS

Granulocyte concentrates prepared from residual leukocyte units contain in vitro functional granulocytes and may be considered as an alternative product in acute situations before regular granulocyte concentrates from stimulated donors are available.

Transfusion Management in Pediatric Oncology Patients

Pediatric oncology patients will likely require numerous transfusions of blood products, including red blood cell, platelet, and plasma transfusions, during the course of their treatment. Although strong evidence-based guidelines for these products in this patient population do not exist, given the morbidities associated with the receipt of blood products, practitioners should attempt to use restrictive transfusion strategies.

Label-free separation of leukocyte subpopulations using high throughput multiplex acoustophoresis

Multiplex separation of mixed cell samples is required in a variety of clinical and research applications. Herein, we present an acoustic microchip with multiple outlets and integrated pre-alignment channel to enable high performance and label-free separation of three different cell or particle fractions simultaneously at high sample throughput. By implementing a new cooling system for rigorous temperature control and minimal acoustic energy losses, we were able to operate the system isothermally and sort suspensions of 3, 5 and 7 μm beads with high efficiencies (>95.4%) and purities (>96.3%) at flow rates up to 500 μL min-1 corresponding to a throughput of ∼2.5 × 106 beads per min. Also, human viable white blood cells were successfully fractionated into lymphocytes, monocytes and granulocytes with high purities of 96.5 ± 1.6%, 71.8 ± 10.1% and 98.8 ± 0.5%, respectively, as well as high efficiencies (96.8 ± 3.3%, 66.7 ± 3.2% and 99.0 ± 0.7%) at flow rates up to 100 μL min-1 (∼100 000 cells per min). By increasing the flow rate up to 300 μL min-1 (∼300 000 cells per min) both lymphocytes and granulocytes were still recovered with high purities (92.8 ± 1.9%, 98.2 ± 1 .0%), whereas the monocyte purity decreased to 20.9 ± 10.3%. The proposed isothermal multiplex acoustophoresis platform offers efficient fractionation of complex samples in a label-free and continuous manner at thus far unreached high sample throughput rates.

Ex vivo Manufactured Neutrophils for Treatment of Neutropenia-A Process Economic Evaluation

Neutropenia is a common side-effect of acute myeloid leukemia (AML) chemotherapy characterized by a critical drop in neutrophil blood concentration. Neutropenic patients are prone to infections, experience poorer clinical outcomes, and require expensive medical care. Although transfusions of donor neutrophils are a logical solution to neutropenia, this approach has not gained clinical traction, primarily due to challenges associated with obtaining sufficiently large numbers of neutrophils from donors whilst logistically managing their extremely short shelf-life. A protocol has been developed that produces clinical-scale quantities of neutrophils from hematopoietic stem and progenitor cells (HSPC) in 10 L single-use bioreactors (1). This strategy could be used to mass produce neutrophils and generate sufficient cell numbers to allow decisive clinical trials of neutrophil transfusion. We present a bioprocess model for neutrophil production at relevant clinical-scale. We evaluated two production scenarios, and the impact on cost of goods (COG) of multiple model parameters including cell yield, materials costs, and process duration. The most significant contributors to cost were consumables and raw materials, including the cost of procuring HSPC-containing umbilical cord blood. The model indicates that the most cost-efficient culture volume (batch size) is ~100 L in a single bioreactor. This study serves as a framework for decision-making and optimization strategies when contemplating the production of clinical quantities of cells for allogeneic therapy.

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.

Effect and clinical value of coagulation test on adverse reactions of blood transfusion in patients with major bleeding in ectopic pregnancy

Influence and clinical value of coagulation test on adverse reactions of blood transfusion in patients with major bleeding of ectopic pregnancy were analyzed. Six hundred and twenty-seven cases of ectopic pregnancy admitted to Zibo First Hospital from July 2014 to March 2017 were retrospectively analyzed. The 369 patients who had adverse reactions after blood transfusion were selected as the experimental group. Another 258 patients without adverse reaction after blood transfusion were selected as the control group. Blood samples were collected 8 h before and after blood transfusion in both groups, and blood test was performed including blood count (RBC), white blood cell count (WBC), platelet count (PLT), HB, hematocrit (HCT), as well as indicators of coagulation, including thrombin time (TT), prothrombin time (PT), activated partial thromboplastin time (APTT) and fibrinogen (FIB). There was no significant difference between the two groups in blood routine and blood coagulation test (P>0.05). After transfusion, the RBC, WBC, PLT, HB and HCT in the experimental group were significantly lower than those in the control group (P<0.05). TT, PT and APTT were higher than those in the control group (P<0.05), while FIB was significantly lower than that in the control group (P<0.001). The coagulation in the experimental group after blood transfusion was significantly worse than that in the control group. Coagulation test can be used as a marker of adverse reactions after transfusion in patients with massive bleeding in pregnancy, providing reference and guidance for clinical diagnosis and treatment.

Quantitative Simulations Predict Treatment Strategies Against Fungal Infections in Virtual Neutropenic Patients

The condition of neutropenia, i.e., a reduced absolute neutrophil count in blood, constitutes a major risk factor for severe infections in the affected patients. Candida albicans and Candida glabrata are opportunistic pathogens and the most prevalent fungal species in the human microbiota. In immunocompromised patients, they can become pathogenic and cause infections with high mortality rates. In this study, we use a previously established approach that combines experiments and computational models to investigate the innate immune response during blood stream infections with the two fungal pathogens C. albicans and C. glabrata. First, we determine immune-reaction rates and migration parameters under healthy conditions. Based on these findings, we simulate virtual patients and investigate the impact of neutropenic conditions on the infection outcome with the respective pathogen. Furthermore, we perform in silico treatments of these virtual patients by simulating a medical treatment that enhances neutrophil activity in terms of phagocytosis and migration. We quantify the infection outcome by comparing the response to the two fungal pathogens relative to non-neutropenic individuals. The analysis reveals that these fungal infections in neutropenic patients can be successfully cleared by cytokine treatment of the remaining neutrophils; and that this treatment is more effective for C. glabrata than for C. albicans.

How neutrophils kill fungi

Neutrophils play a critical role in the prevention of invasive fungal infections. Whereas mouse studies have demonstrated the role of various neutrophil pathogen recognition receptors (PRRs), signal transduction pathways, and cytotoxicity in the murine antifungal immune response, much less is known about the killing of fungi by human neutrophils. Recently, novel primary immunodeficiencies have been identified in patients with a susceptibility to fungal infections. These human 'knock-out' neutrophils expand our knowledge to understand the role of PRRs and signaling in human fungal killing. From the studies with these patients it is becoming clear that neutrophils employ fundamentally distinct mechanisms to kill Candida albicans or Aspergillus fumigatus.

Transfusion challenges in hematology oncology and hematopoietic stem cell transplant - Literature review and local experience

Transfusion medicine plays a vital role in the supportive care of patients receiving therapy for hematology, oncology and hematopoietic stem cell transplants (HSCT). With advances in therapy with more intensive chemotherapy or radiotherapy, patients usually develop cytopenias and need frequent transfusion support with packed red blood cells, granulocyte transfusion or platelets to support them until they recover from the effect of therapy. HSCT poses unique challenges for transfusion medicine, since transplant recipients may require substantial transfusion support due to cytopenias associated with toxic medications, decreased marrow reserve, infection or their malignancy. Transfusion support has many complications, mainly immune mediated and infectious complications. Jehovah's Witness patients deny transfusions of blood products as a therapeutic option and, consequently, management of their disease with chemotherapy and stem cell transplant after myeloablative therapy is quite challenging. This review describes the challenges of transfusion support in managing hemato-oncology and stem cell transplant patients and highlights a local experience in transplanting two Jehovah's Witness patients.

Dexamethasone promotes granulocyte mobilization by prolonging the half-life of granulocyte-colony-stimulating factor in healthy donors for granulocyte transfusions

BACKGROUND

Granulocyte transfusion (GTX) is a potential approach to correcting neutropenia and relieving the increased risk of infection in patients who are refractory to antibiotics. To mobilize enough granulocytes for transfusion, healthy donors are premedicated with granulocyte-colony-stimulating factor (G-CSF) and dexamethasone. Granulocytes have a short circulatory half-life. Consequently, patients need to receive GTX every other day to keep circulating granulocyte counts at an acceptable level. We investigated whether plasma from premedicated donors was capable of prolonging neutrophil survival and, if so, which factor could be held responsible.

STUDY DESIGN AND METHODS

The effects of plasma from G-CSF/dexamethasone-treated donors on neutrophil survival were assessed by annexin-V, CD16. and CXCR4 staining and nuclear morphology. We isolated an albumin-bound protein using α-chymotrypsin and albumin-depletion and further characterized it using protein analysis. The effects of dexamethasone and G-CSF were assessed using mifepristone and G-CSF-neutralizing antibody. G-CSF plasma concentrations were determined by Western blot and Luminex analyses.

RESULTS

G-CSF/dexamethasone plasma contained a survival-promoting factor for at least 2 days. This factor was recognized as an albumin-associated protein and was identified as G-CSF itself, which was surprising considering its reported half-life of only 4.5 hours. Compared with coadministration of dexamethasone, administration of G-CSF alone to the same GTX donors led to a faster decline in circulating G-CSF levels, whereas dexamethasone itself did not induce any G-CSF, demonstrating a role for dexamethasone in increasing G-CSF half-life.

CONCLUSION

Dexamethasone increases granulocyte yield upon coadministration with G-CSF by extending G-CSF half-life. This observation might also be exploited in the coadministration of dexamethasone with other recombinant proteins to modulate their half-life.

Update on granulocyte transfusions: accumulation of promising data, but still lack of decisive evidence

PURPOSE OF REVIEW

Inconsistent results regarding the clinical efficacy of granulocyte transfusions for the treatment or prophylaxis of life-threatening infections in neutropenic patients have been attributed to insufficient number of transfused neutrophils. Since the introduction of granulocyte colony-stimulating factor (G-CSF) to the granulocyte mobilization regimen in the 1990s, the number of transfused cells significantly increased, which directly translated to a significant increase in absolute neutrophil counts in the transfused patients.

RECENT FINDINGS

For therapeutic granulocyte transfusions, neither of the two randomized controlled studies in the G-CSF era could demonstrate a clear clinical benefit. However, a number of small studies or case series have suggested its clinical efficacy, including one that demonstrated the clinical response against drug-resistant invasive fusariosis. For prophylactic granulocyte transfusions, there have been scarce reports in the G-CSF era. A pulmonary reaction is the most significant adverse event after granulocyte transfusions, although its reported frequency varies among studies.

SUMMARY

Despite the expectation that the increased number of transfused neutrophils enables the clear demonstration of the clinical benefit, the role of therapeutic granulocyte transfusions remains controversial. Future directions may include: identifying the patient population who would benefit most from granulocyte transfusions; minimizing the risk of adverse events by identifying the risk factors and the prevention methods; and finding a way to prove the clinical benefit of granulocyte transfusions in therapeutic and prophylactic settings.

Thirty-minutes’ exposure to smartphone call triggers neutrophil activation in vitro

Background:

Despite accumulating evidence about the negative health effects of exposure to electromagnetic fields emitted by mobile phones, no information is available on the potential impact of radiofrequency (RF) waves on polymorphonuclear leukocytes biology.

Methods:

Two sequential whole blood tubes were collected from 16 ostensibly healthy volunteers. After placing the former tube of each subject in a plastic rack, 1 cm from a commercial smartphone (carrier frequency, 900 MHz), a call was placed on the smartphone and a communication lasting 30 min was manually activated. The latter blood tube of each volunteer was placed in another plastic rack, for an identical period of time, avoiding close contact with sources of RF waves. A complete blood count was then assessed in all whole blood samples, using Advia 2120.

Results:

The 30-min exposure of blood to RF waves did not induce significant variations of total and differential leukocyte counts. A significant decrease was however observed for many neutrophils parameters, with median percentage variation of −3.9% for the lobularity index (LI), −29.8% for the myeloperoxidase index (MPXI), −0.6% for the neutrophil cluster mean x (NEUTx) and −0.7% for the neutrophil cluster mean y (NEUTy), respectively. The percentage of blood samples with reduced values after exposure to RF waves was 81% for LI, 88% for NEUTx and 100% for both MPXI and NEUTy.

Conclusions:

The results of this study show that exposure to smartphone RF waves triggers activation of neutrophils in vitro, as mirrored by the significant variations observed in many activation parameters in Advia 2120.

Dose-Dependent Effect of Granulocyte Transfusions in Hematological Patients with Febrile Neutropenia

It is still under debate whether granulocyte transfusions (GTs) substantially increase survival in patients with febrile neutropenia. We retrospectively examined data relative to 96 patients with hematological malignancies receiving 491 GTs during 114 infectious episodes (IE). Patients were grouped according to the median doses of granulocytes transfused during the infectious episode (low-dose group: <1.5-x10⁸ cells/Kg; standard-dose group: 1.5–3.0x10⁸ cells/Kg and high-dose group: >3.0x10⁸ cells/Kg). The impact of clinical, microbiological and GT-related variables on the infection-related mortality (IRM) was investigated. The IRM was not influenced by the number of GTs or by the total amount of granulocytes received, whereas a dose-related effect of the median dose received for IE was detected at univariate analysis (IRM of 18.4% in the standard-dose group, 44.4% in the low-dose group and 48.4% in the high-dose group, p = 0.040) and confirmed at multivariate analysis (OR 3.7, IC 95% 1.5–8.9; 0.004 for patients not receiving standard doses of GTs). Moreover, patients receiving GTs at doses lower or greater than standard had increased risk for subsequent ICU admission and reduced overall survival. The dose-related effect of GTs was confirmed in bacterial but not in fungal infections. Preliminary findings obtained from a subgroup of patients candidate to GTs revealed that levels of inflammatory response mediators increase in a dose-related manner after GTs, providing a possible explanation for the detrimental effect exerted by high-dose transfusions. GTs can constitute a valuable tool to improve the outcome of infections in neutropenic patients, provided that adequate recipient-tailored doses are supplied. Further investigations of the immunomodulatory effects of GTs are recommended.

Impaired killing of Candida albicans by granulocytes mobilized for transfusion purposes: a role for granule components

Granulocyte transfusions are used to treat neutropenic patients with life-threatening bacterial or fungal infections that do not respond to anti-microbial drugs. Donor neutrophils that have been mobilized with granulocyte-colony stimulating factor (G-CSF) and dexamethasone are functional in terms of antibacterial activity, but less is known about their fungal killing capacity. We investigated the neutrophil-mediated cytotoxic response against C. albicans and A. fumigatus in detail. Whereas G-CSF/dexamethasone-mobilized neutrophils appeared less mature as compared to neutrophils from untreated controls, these cells exhibited normal ROS production by the NADPH oxidase system and an unaltered granule mobilization capacity upon stimulation. G-CSF/dexamethasone-mobilized neutrophils efficiently inhibited A. fumigatus germination and killed Aspergillus and Candida hyphae, but the killing of C. albicans yeasts was distinctly impaired. Following normal Candida phagocytosis, analysis by mass spectrometry of purified phagosomes after fusion with granules demonstrated that major constituents of the antimicrobial granule components, including major basic protein (MBP), were reduced. Purified MBP showed candidacidal activity, and neutrophil-like Crisp-Cas9 NB4-KO-MBP differentiated into phagocytes were impaired in Candida killing. Together, these findings indicate that G-CSF/dexamethasone-mobilized neutrophils for transfusion purposes have a selectively impaired capacity to kill Candida yeasts, as a consequence of an altered neutrophil granular content.

Role of granulocyte transfusions in invasive fusariosis: systematic review and single-center experience

BACKGROUND

Invasive Fusarium infection is relatively refractory to available antifungal agents. Invasive fusariosis (IF) occurs almost exclusively in the setting of profound neutropenia and/or systemic corticosteroid use. Treatment guidelines for IF are not well established, including the role of granulocyte transfusions (GTs) to counter neutropenia.

STUDY DESIGN AND METHODS

We conducted a systematic review, identifying IF cases where GTs were used as adjunctive therapy to antifungal agents and also report a single-center case series detailing our experience (1996-2012) of all IF cases treated with antifungal agents and GTs. In the systematic review cases, GTs were predominantly collected from nonstimulated donors whereas, in the case series, they were universally derived from dexamethasone- and granulocyte-colony-stimulating factor-stimulated donors.

RESULTS

Twenty-three patients met inclusion criteria for the systematic review and 11 for the case series. Response rates after GTs were 30 and 91% in the review and case series, respectively. Survival to hospital discharge remained low at 30 and 45%, respectively. Ten patients in the systematic review and three in the case series failed to achieve hematopoietic recovery and none of these survived. In the case series, donor-stimulated GTs generated mean "same-day" neutrophil increments of 3.35 × 10(9)  ± 1.24 × 10(9) /L and mean overall posttransfusion neutrophil increments of 2.46 × 10(9)  ± 0.85 × 10(9) /L. Progressive decrements in neutrophil response to GTs in two cases were attributed to GT-related HLA alloimmunization.

CONCLUSION

In patients with IF, donor-stimulated GTs may contribute to high response rates by effectively bridging periods of neutropenia or marrow suppression. However, their utility in the absence of neutrophil recovery remains questionable.