Impact of hydroxyethyl starch and modified fluid gelatin on granulocyte phenotype and function

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.

Effect of Arginine Vasopressin on Human Neutrophil Function Under Physiological and Sepsis-Associated Conditions

This study examines how different concentrations of arginine vasopressin (AVP) and its preservative chlorobutanol (ClB) impact the immune functions of human polymorphonuclear neutrophils (PMNs), which are crucial in the immune response, particularly in sepsis. Using a model to simulate the physiological, sepsis-related, and therapeutic AVP levels in plasma, we analysed how AVP and ClB affect PMN activities, including reactive oxygen species (ROS) production, NETosis, antigen expression, and migration. PMNs were isolated from whole human blood and assessed using flow cytometry and live cell imaging. The results indicated that neither AVP nor ClB significantly affected PMN viability, antigen expression, NETosis, or ROS production in response to N-Formylmethionine-leucyl-phenylalanine, or fMLP, and tumour necrosis factor alpha. In the migration assays, concentration-dependent effects were observed. At physiological AVP levels, PMN migration showed no reduction, while the sepsis-associated AVP levels initially reduced migration before returning to the baseline or even increasing. The therapeutic AVP concentrations showed similar migration to that in the controls, while high concentrations progressively inhibited migration. ClB, regardless of its concentration, enhanced PMN migration. These findings suggest that AVP during sepsis may impair PMN migration, potentially contributing to tissue damage and systemic complications. This highlights AVP's role as a possible immune modulator in complex immune responses.

Neutrophils in the Spotlight-An Analysis of Neutrophil Function and Phenotype in ARDS

Acute respiratory distress syndrome (ARDS) is a complex disease pattern in which pathogenesis polymorphonuclear neutrophil granulocytes (PMN) play a key role. In previous experiments, we could show that interaction with collagen III (an important component of pulmonary tissue) is a possible trigger of neutrophil reactive oxygen species (ROS) production. To investigate possible correlations, further elucidate ARDS pathophysiology, and maybe find pharmacological targets, we evaluated PMNs from blood (circulating PMNs: cPMNs) and tracheal secretion (tPMNs) from patients with and without ARDS with regard to function and phenotype. Blood samples and tracheal secretions were obtained from intensive care patients with and without ARDS. Isolation of cPMN was performed by density-gradient gravity sedimentation without centrifugation. For tPMN isolation, endotracheal aspirate was filtered, and tPMNs were separated from the remaining aspirate using a particle filter. Specific surface epitopes (CD66b, CD62L, fMLP-receptor, LOX-1, CD49d, CD29, CD11b) of the isolated PMN cells were labeled with antibody-coupled dyes and analyzed by flow cytometry. Neutrophil ROS production before and after activation with N-formyl-methyl-leucyl-phenylalanine (fMLP) and tumor necrosis factor α (TNFα) was quantified using rhodamine-123. In addition, a qualitative cytological hematoxylin-eosin (HE) staining was performed with a portion of the secretion. tPMNs were observed in both bloody and mucosal tracheal secretions from ARDS patients. The epitope distribution on cPMNs and tPMNs differed significantly in patients with and without ARDS: tPMNs generally showed increased expression of CD66b, LOX-1 and fMLP-receptor compared to cPMNs, and decreased expression of CD62L. The CD49d levels of all cPMNs were at the same level as tPMNs in ARDS, whereas CD49d expression was increased on tPMNs without ARDS. ROS production was significantly stimulated by fMLP/TNFα in cPMNs regardless of the patient group, while it was similarly increased in tPMNs with and without stimulation. Increased expression of CD66b, LOX-1 and fMLP-receptor on tPMNs indicated a higher activity status compared to cPMNs. Increased CD49d expression on tPMNs without ARDS marks different PMN surface changes in lung disease. PMNs appear to be in a more activated state in lung secretions than in blood, as indicated by higher CD66b and lower CD62L expression, higher constitutive ROS production and lower excitability with fMLP and TNFα. In the context of possible CD49d-triggered ROS production, it is noteworthy that CD49d is downregulated in secretion from patients with ARDS compared to patients without. This phenotypic and functional PMN characterization can provide valuable diagnostic and therapeutic information for the intensive care treatment of ARDS patients.

Impact of Nitric Oxide on Polymorphonuclear Neutrophils' Function

BACKGROUND

There is increasing evidence that nitric oxide (nitrogen monoxide, NO) significantly influences immune cellular responses, including those from polymorphonuclear leukocytes (PMNs).

OBJECTIVE

The aim of this study was to examine a possible effect of NO on PMNs' function (chemotaxis, production of reactive oxygen species (ROS), and NETosis) using live cell imaging. Moreover, we investigated PMN surface epitope and neutrophil oxidative burst under the influence of NO by flow cytometric analysis.

METHODS

Whole blood samples were obtained from healthy volunteers, and PMNs were isolated by density centrifugation. Live cell imaging using type I collagen matrix in µSlide IBIDI chemotaxis chambers was conducted in order to observe N-formyl-L-methionyl-L-leucyl-phenylalanine (fMLP)-stimulated PMN chemotaxis, ROS production, and NETosis. In the test group, NO was continuously redirected into the climate chamber of the microscope, so the chemotaxis chambers were surrounded by NO. The same experimental setup without NO served as a control. In addition, isolated PMNs were incubated with nitrogen monoxide (NO) or without (the control). Subsequently, flow cytometry was used to analyze neutrophil antigen expression and oxidative burst.

RESULTS

Our live cell imaging results demonstrated a migration-promoting effect of NO on PMNs. We observed that in the case of prior stimulation by fMLP, NO has no effect on the time course of neutrophil ROS production and NET release. However, flow cytometric analyses demonstrated an increase in ROS production after pretreatment with NO. No NO-dependent differences for the expression of CD11b, CD62L, or CD66b could be observed.

CONCLUSIONS

We were able to demonstrate a distinct effect of NO on PMNs' function. The complex interaction between NO and PMNs remains a major research focus, as the exact mechanisms and additional influencing factors remain elusive. Future studies should explore how varying NO concentrations and the timing of NO exposure relative to PMN activation affect its influence.

Effects of Pressure, Hypoxia, and Hyperoxia on Neutrophil Granulocytes

Background: The application of normo- and hyperbaric O2 is a common therapy option in various disease patterns. Thereby, the applied O2 affects the whole body, including the blood and its components. This study investigates influences of pressure and oxygen fraction on human blood plasma, nutrient media, and the functions of neutrophil granulocytes (PMNs). Methods: Neutrophil migration, reactive oxygen species (ROS) production, and NETosis were examined by live cell imaging. The treatment of various matrices (Roswell Park Memorial Institute 1640 medium, Dulbecco's Modified Eagle's Medium, H2O, human plasma, and isolated PMNs) with hyperbaric oxygen (HBO) was performed. In addition, the expression of different neutrophil surface epitopes (CD11b, CD62L, CD66b) and the oxidative burst were investigated by flow cytometry (FACS). The application of cold atmospheric plasma (CAP) to normoxic and normobaric culture media served as a positive control. Soluble reaction products such as H2O2, reactive nitrogen species (RNS: NO2- and NO3-), and ROS-dependent dihydrorhodamine oxidation were quantified by fluoro- and colorimetric assay kits. Results: Under normobaric normoxia, PMNs migrate slower and shorter in comparison with normobaric hyper- or hypoxic conditions and hyperbaric hyperoxia. The pressure component has less effect on the migration behavior of PMNs than the O2 concentration. Individual PMN cells produce prolonged ROS at normoxic conditions. PMNs showed increased expression of CD11b in normobaric normoxia, lower expression of CD62L in normobaric normoxia, and lower expression of CD66b after HBO and CAP treatment. Treatment with CAP increased the amount of ROS and RNS in common culture media. Conclusions: Hyperbaric and normobaric O2 influences neutrophil functionality and surface epitopes in a measurable way, which may have an impact on disorders with neutrophil involvement. In the context of hyperbaric experiments, especially high amounts of H2O2 in RPMI after hyperbaric oxygen should be taken into account. Therefore, our data support a critical indication for the use of normobaric and hyperbaric oxygen and conscientious and careful handling of oxygen in everyday clinical practice.

A study on beneficial impact of the use of medium-molecular-weight hydroxyethyl starch in granulocyte apheresis using continuous-flow cell separator Spectra Optia: A retrospective single-center study at a tertiary care oncology center

INTRODUCTION

Granulocyte transfusion is one of the best therapeutic modalities in prolonged neutropenic patients with severe bacterial/fungal infections. Granulocyte harvest using conventional acid citrate dextrose (ACD) anticoagulant (ACD-A) by apheresis is not satisfactory in comparison to the use of hydroxyethyl starch (HES), but the latter is associated with various adverse events, especially with high-molecular-weight HES.

AIMS AND OBJECTIVE

This study aimed to assess the beneficial impact of the use of medium-molecular-weight (MMW)-HES and trisodium citrate combination over ACD-A in granulocyte apheresis when using Spectra Optia.

MATERIALS AND METHODS

This was a retrospective study comparing granulocyte harvest results with the use of ACD or HES and trisodium citrate combination. All the donors in both the groups received single 600 μg of granulocyte colony-stimulating factor subcutaneous injection followed by 8 mg of dexamethasone tablet 10-12 h and omnacortil 60 mg orally 3 h before harvest. A number of adverse incidents, if any, were observed and noted. Donor/procedure parameters were compared using Mann-Whitney U-test/unpaired t-test.

RESULTS

Granulocyte yield (mean: 3.29 × 1010/unit vs. 4.5 × 1010/unit in the ACD and HES groups, respectively, P ≤ 0.0001) was significantly better in the HES group. The collection efficiency was also better in the HES group (mean: 15.86% vs. 26.70% in the ACD and HES groups, respectively, P ≤ 0.0001) in the ACD and HES groups, respectively. There was no significant adverse event noted in any of these two groups.

CONCLUSION

In our study, granulocytes with optimum yield can be easily harvested with Spectra Optia cell separator using 6% HES (MMW) and trisodium citrate combination with standard 12-h interval gap between mobilization and harvest. This strategy can also have no or minimal extra cost burden to patients.

Obesity Correlates with Chronic Inflammation of the Innate Immune System in Preeclampsia and HELLP Syndrome during Pregnancy

HELLP syndrome is characterized by hemolysis, elevated liver enzymes, and a low platelet count and poses an increased risk to the pregnant woman and the unborn child. Individual risk factors such as obesity may alter immunocompetence and influence the course of preeclampsia (PE) or HELLP syndrome. Blood samples were collected from 21 pregnant women (7 healthy, 6 with PE, and 8 with HELLP syndrome) and polymorphonuclear neutrophils (PMNs) were subsequently isolated. Production of radical oxygen species (ROS), cell movement, and NETosis were assessed by live-cell imaging. Surface protein expression and oxidative burst were analyzed by flow cytometry. PE and HELLP patients had significantly higher BMI compared to the healthy control group. Depending on the expression of CD11b, CD62L, and CD66b on PMNs, a surface protein activation sum scale (SPASS) was calculated. PMNs from patients with high SPASS values showed prolonged and more targeted migration with delayed ROS production and NETosis. Obesity is associated with a chronic inflammatory state, which in combination with immunological triggers during pregnancy could modulate PMN functions. Pregnant women with higher BMI tend to have higher SPASS values, indicating activation of the innate immune system that could co-trigger PE or HELLP syndrome.

Granulocyte concentrate splitting does not affect phenotype and function

BACKGROUND

More granulocyte concentrates (GCs) could be produced for more patients from the same donor if apheresis bags were split and stored for longer periods of time. Hence, we tested the hypothesis that splitting and extension of storage of GCs do not impair granulocyte function or viability.

STUDY DESIGN AND METHODS

Granulocyte apheresis concentrates were produced using modified fluid gelatin as a separation enhancer, split into two portions, and stored for 24 and 48 h. Granulocyte function, represented by cell migration, reactive oxygen species (ROS) production, and neutrophil extracellular trap formation (NETosis), was measured by live-cell imaging. ROS production, adhesive surface protein expression, and viability were measured by flow cytometry.

RESULTS

Splitting had no effect on any of the tested parameters. After 24 h of storage, live-cell imaging showed no significant difference in migration, time to maximum ROS production, time to half-maximum NETosis, viability, or CD11b expression, but ROS production induced by phorbol 12-myristate 13-acetate (PMA) decreased from an initial median fluorescence intensity of 1775-590 artificial units. After 48 h, PMA-induced ROS production, viability, and migration declined, as reflected by decreases in median total distance (119 vs. 63.5 μm) and median Euclidean distance (30.75 vs. 14.3 μm).

CONCLUSION

Splitting GC products has no effect on granulocyte viability or function, but extended storage >24 h does compromise granulocyte function. The findings confirm that GCs should be transfused within 24 h of collection. Longer storage cannot be recommended.

Paralytic Impact of Centrifugation on Human Neutrophils

Centrifugation is a common step in most of the popular protocols for the isolation of neutrophils from whole blood. Inconsistent results from previous studies on neutrophils may originate from an underestimation of the centrifugation effect, as in consequence impaired, not native cells, being investigated. We hypothesize, that centrifugation significantly impairs major neutrophil functions. However, there is no data yet whether the application of g-force itself or the product of g-force and duration of centrifugation (="g-time") defines the impact on neutrophils. Neutrophils were isolated from whole blood via centrifugation with different g-times and subsequently analyzed via live cell imaging for migration, as well as via flow cytometry for oxidative burst and surface antigen expression. Chemotactic migration was significantly reduced with increasing g-time. Oxidative burst decreased likewise the higher the g-time applied. Expression of CD11b was no longer upregulated in response to an n-formylmethionine-leucyl-phenylalanine (fMLP) stimulus in neutrophils having experienced high g-time during the isolation process. We conclude that centrifugation "paralyzes" neutrophils in the form of a significant decrease in functionality. Future investigations on neutrophil granulocytes should reduce the g-time load as far as possible.

Neutrophils-From Bone Marrow to First-Line Defense of the Innate Immune System

Neutrophils (polymorphonuclear cells; PMNs) form a first line of defense against pathogens and are therefore an important component of the innate immune response. As a result of poorly controlled activation, however, PMNs can also mediate tissue damage in numerous diseases, often by increasing tissue inflammation and injury. According to current knowledge, PMNs are not only part of the pathogenesis of infectious and autoimmune diseases but also of conditions with disturbed tissue homeostasis such as trauma and shock. Scientific advances in the past two decades have changed the role of neutrophils from that of solely immune defense cells to cells that are responsible for the general integrity of the body, even in the absence of pathogens. To better understand PMN function in the human organism, our review outlines the role of PMNs within the innate immune system. This review provides an overview of the migration of PMNs from the vascular compartment to the target tissue as well as their chemotactic processes and illuminates crucial neutrophil immune properties at the site of the lesion. The review is focused on the formation of chemotactic gradients in interaction with the extracellular matrix (ECM) and the influence of the ECM on PMN function. In addition, our review summarizes current knowledge about the phenomenon of bidirectional and reverse PMN migration, neutrophil microtubules, and the microtubule organizing center in PMN migration. As a conclusive feature, we review and discuss new findings about neutrophil behavior in cancer environment and tumor tissue.

Granulocyte transfusions made with modified fluid gelatin in pediatric and adolescent patients with prolonged neutropenia

BACKGROUND

Granulocyte transfusions (GT) are used to treat progressive systemic or local infections in prolonged neutropenic patients with antibiotic or antifungal resistance. Granulocytes are most commonly collected from whole blood by apheresis using hydroxyethyl starch (HES) as the red blood cell (RBC) sedimentation agent. This is the first study on the safety and efficacy of transfusing granulocytes collected with modified fluid gelatin (MFG) instead of HES to pediatric patients.

METHODS

Clinical data from 46 pediatric and adolescent patients receiving at least one MFG-based granulocyte transfusion and in total 295 granulocyte concentrates from July 2013 to August 2019 at our local university medical center were evaluated retrospectively.

RESULTS

Forty-one patients (89%) survived at least 21 days after their last granulocyte transfusion. These survivors had lower CRP values and higher leukocyte counts after GT than non-survivors (mean delta of -5.34 mg/dl vs. -11.99 mg/dl and + 0.62 × 10³ /μl vs. +0.18 × 10³ /μl of all GT, respectively). The neutrophil corrected count increment (CCI) was 68.72 mm² /ml in survivors versus 28.00 mm² /ml in non-survivors. There were no major or severe adverse events.

CONCLUSION

This study suggests that modified fluid gelatin is a safe and effective alternative to hydroxyethyl starch for the collection of granulocytes for transfusion to prolonged neutropenic patients with progressive systemic or local infections refractory to antibiotic or antifungal therapy.

Granulocyte collection by polymorphonuclear cell-targeting apheresis with medium-molecular-weight hydroxyethyl starch

Granulocyte transfusion (GTX) is a therapeutic option for patients with prolonged neutropenia suffering from severe infections. Efficient granulocyte collection by apheresis from donors requires clear separation of granulocytes from red blood cells (RBCs), and infusion of high-molecular-weight (MW) hydroxyethyl starch (HES) facilitates RBC sedimentation. Recent research has shown that apheresis with medium-MW HES may prevent adverse effects of high-MW HES on donors, but the rationale for collection with medium-MW HES has yet to be evaluated. To validate the use of medium-MW HES, we first performed experiments with whole blood samples to determine how efficiently high-, medium- and low-MW HES separated granulocytes from RBCs, and found that medium-MW HES was just as efficient as high-MW HES. We also reviewed clinical data of granulocyte apheresis at our institution to evaluate granulocyte yields. Retrospective analysis of granulocyte collection revealed that apheresis with medium-MW HES yielded sufficient granulocytes for GTX and that donor anemia reduced collection efficiency. These results collectively may help us to establish a safer method for apheresis targeting polymorphonuclear granulocytes as an alternative to high-MW HES.

Propofol Ameliorates Exaggerated Human Neutrophil Activation in a LPS Sepsis Model

Background

Sepsis is a leading cause of morbidity and mortality worldwide. Many patients suffering from sepsis are treated on intensive care units and many of them require mechanical ventilation under sedation or general anesthesia. Propofol, a drug used for these purposes, is known to interact with polymorphonuclear granulocytes (PMNs). Therefore, the aim of this study was to investigate the influence of propofol on PMN functions after experimental Gram-negative induced sepsis using lipopolysaccharide (LPS) stimulation.

Methods

A total of 34 granulocyte-enriched samples were collected from healthy subjects. PMNs were isolated by density gradient centrifugation and incubated simultaneously with either 6 µg/mL or 60 µg/mL propofol, or none (control). Additionally, the experimental sepsis samples were incubated with either 40 pg/mL or 400 pg/mL LPS. Live cell imaging was conducted in order to observe granulocyte chemotactic migration, ROS production, and NETosis. Flow cytometry was used to analyze viability and antigen expression.

Results

Propofol led to significantly reduced PMN track length (p < 0.001) and track speed (p < 0.014) after LPS-induced sepsis in a dose-dependent manner. NETosis (p = 0.018) and ROS production (p = 0.039) were accelerated by propofol without LPS incubation, indicating improved immune function. Propofol also ameliorated LPS-induced increased NETosis and ROS-production. Antigen expression for CD11b, CD62l and CD66b was unaffected by propofol.

Conclusion

Propofol improves LPS-induced exaggerated PMN activation in an ex vivo model. Beneficial effects due to restored immune function in septic patients might be possible, but needs further investigation.

Cold Atmospheric Plasma Promotes the Immunoreactivity of Granulocytes In Vitro

Cold atmospheric plasma (CAP) reduces bacteria and interacts with tissues and cells, thus improving wound healing. The CAP-related induction of neutrophils was recently described in stained sections of wound tissue in mice. Consequently, this study aimed to examine the functionality of human polymorphonuclear cells (PMN)/granulocytes through either a plasma-treated solution (PTS) or the direct CAP treatment with different plasma modes and treatment durations. PTS analysis yielded mode-dependent differences in the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) after CAP treatment. Live-cell imaging did not show any chemo-attractive or NETosis-inducing effect on PMNs treated with PTS. The time to maximum ROS production (TmaxROS) in PMNs was reduced by PTS and direct CAP treatment. PMNs directly treated with CAP showed an altered cell migration dependent on the treatment duration as well as decreased TmaxROS without inducing apoptosis. Additionally, flow cytometry showed enhanced integrin and selectin expression, as a marker of activation, on PMN surfaces. In conclusion, the modification of PMN immunoreactivity may be a main supporting mechanism for CAP-induced improvement in wound healing.

The influence of extracellular tissue on neutrophil function and its possible linkage to inflammatory diseases

BACKGROUND

Migration, production of reactive oxygen species (ROS), release of myeloperoxidase (MPO), and NETosis are functional immunological reactions of elementary importance for polymorphonuclear neutrophils (PMN). Unregulated inflammatory response of PMN within tissues plays a key role in the pathophysiology of several diseases. However, little is known about the behavior of PMN after migration through blood vessel walls. Therefore, we investigated the influence of the extracellular matrix (ECM) on PMN function.

MATERIALS AND METHODS

We established an in vitro chemotaxis model of type I and III collagen, fibrin, and herbal agarose tissues using µ-slide chemotaxis devices and N-formylmethionine-leucyl-phenylalanine (fMLP). PMN within the matrices were assessed with a fluorescent time-lapse microscope for live-cell imaging.

RESULTS

PMN function was obviously influenced by the ECM. Type III collagen had an inhibitory effect on PMN migration regarding track length, direction, and targeting. Type III collagen also had an accelerating effect on neutrophil ROS production. Agarose had an inhibitory effect on MPO release and fibrin a retarding effect on NETosis.

CONCLUSION

Because of the high abundance of type III collagen in lung and skin matrices, the interaction of PMN with the respective matrix could be an important mechanism in the pathophysiology of acute respiratory distress syndrome and pyoderma gangrenosum.

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.

Potential Impact of Local Anesthetics Inducing Granulocyte Arrest and Altering Immune Functions on Perioperative Outcome

Introduction

Local anesthetics (LAs) are frequently used during anesthesia; however, they may influence granulocyte function which in turn could modify immune responses in the perioperative period. Therefore, the aim of this study was to investigate the impact of clinically used doses of bupivacaine and lidocaine on granulocyte function with regard to migration, reactive oxygen species (ROS) production, neutrophil extracellular traps (NETosis) formation, and viability.

Methods

A total of 38 granulocyte-enriched samples from healthy subjects were obtained by whole blood lysis. Polymorphonuclear neutrophil (PMN) samples were incubated simultaneously with different concentrations of either bupivacaine (0.03–3.16 mmol/L) or lidocaine (0.007–14.21 mmol/L), or without drug (control). Live cell imaging was conducted in order to observe granulocyte chemotaxis, migration, ROS production, and NETosis. Flow cytometry was used to analyze viability and antigen expression.

Results

The track length (TL) of PMNs exposed to bupivacaine concentrations of 0.16 mmol/L and above significantly decreased compared to the control. Low concentrations of lidocaine were associated with slight but significant increases in TL, whereas this changed with concentrations above 1.4 mmol/L, showing a significant decrease in TL. PMN incubated with bupivacaine concentrations of 1.58 mmol/L and above or lidocaine concentrations of at least 3.6 mmol/L showed no migration or chemotaxis at all. Time to onset of maximal ROS production and time for half-maximal NETosis decreased in a dose-dependent manner for both substances. Equipotency in NETosis induction was reached by bupivacaine (1.1 mmol/L) at significantly lower concentrations than lidocaine (7.96 mmol/L). Cell viability and oxidative burst were unaffected by LAs.

Conclusion

Local anesthetics in clinically used doses ameliorate granulocyte defense mechanisms, thus indicating their potentially decisive effect during the perioperative period.

Polymorphonuclear Cell Chemotaxis and Suicidal NETosis: Simultaneous Observation Using fMLP, PMA, H7, and Live Cell Imaging

Chemotaxis and the formation of suicidal neutrophil extracellular traps (suicidal NETosis) are key functions of polymorphonuclear cells (PMNs). Neutrophil extracellular traps in particular are known to be significantly involved in the severity of inflammatory and immunological disorders such as rheumatoid arthritis and Crohn's disease. Therefore, detailed knowledge of PMNs is essential for analyzing the mechanisms involved in, and developing new therapies for, such diseases. To date, no standard method to analyze these cell activities has been established. This study used in vitro live cell imaging to simultaneously observe and analyze PMN functions. To demonstrate this, the effects of phorbol-12-myristat-13-acetat (PMA, 0.1-10 nM), N-formylmethionine-leucyl-phenylalanine (fMLP, 10 nM), and protein kinase C inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7) on PMN chemotaxis and suicidal NETosis were studied. PMA (1 nM-10 nM) resulted in significant concentration-dependent behavior in chemotaxis and an earlier onset of maximum oxidative burst and NET formation of up to 44%. When adding H7, PMA-triggered PMN functions were reduced, demonstrating that all three functions rely mostly on protein kinase C (PKC) activity, while PKC is not essential for fMLP-induced PMN activity. Thus, the method here described can be used to objectively quantify PMN functions and, especially through the regulation of the PKC pathway, could be useful in further clinical studies of immunological disorders.

Therapeutic Anticoagulation with Argatroban and Heparins Reduces Granulocyte Migration: Possible Impact on ECLS-Therapy?

Introduction

Anticoagulants such as argatroban and heparins (low-molecular-weight and unfractionated) play an immense role in preventing thromboembolic complications in clinical practice. Nevertheless, they can also have a negative effect on the immune system. This study is aimed at investigating the influence of these substances on polymorphonuclear neutrophils (PMNs), whose nonspecific defense mechanisms can promote thrombogenesis.

Methods

Blood samples from 30 healthy volunteers were investigated, whereby PMNs were isolated by density gradient centrifugation and incubated with 0.8 μg/mL of argatroban, 1.0 U/mL of low-molecular-weight heparin (LMWH), 1.0 U/mL of unfractionated heparin (UFH), or without drug (control). A collagen-cell mixture was prepared and filled into 3D μ-slide chemotaxis chambers (IBIDI® GmbH, Germany). Stimulation was initiated by using a chemokine gradient of n-formyl-methionine-leucyl-phenylalanine (fMLP), and microscopic observation was conducted for 4.5 hours. The cells' track length and track straightness, as well as the number of attracted granulocytes, level of ROS (reactive oxygen species) production, and NET (neutrophil extracellular traps) formation, were analyzed and categorized into migration distances and time periods.

Results

All three anticoagulants led to significantly reduced PMN track lengths, with UFH having the biggest impact. The number of tracks observed in the UFH group were significantly reduced compared to the control group. Additionally, the UFH group demonstrated a significantly lower track straightness compared to the control. ROS production and NET formation were unaffected.

Conclusion

Our data provide evidence that anticoagulants have an inhibitory effect on the extent of PMN migration and chemotactic migration efficiency, thus indicating their potential immune-modulatory and prothrombotic effects.