Autoimmune and other acquired neutropenias

Co-infection of nervous necrosis virus and Vibrio harveyi increased mortality and worsened the disease severity in the orange-spotted grouper (Epinephelus coioides)

Co-infections of different pathogenic microorganisms usually cause complex effects, and receive more attention. Red-grouper nervous necrosis virus (RGNNV) and Vibrio are the common viral and bacterial pathogens of fish, and are often detected simultaneously in diseased fish. However, the understanding of co-infection of RGNNV and Vibrio is still unclear. In this study, we have established a grouper (Epinephelus coioides) model of the co-infection of RGNNV and Vibrio harveyi (V. harveyi). Compared with single pathogen infection, co-infection of RGNNV and V. harveyi significantly caused more severe pathologic changes with higher mortality (P < 0.05), and promoted the proliferation of the pathogens by RNA-FISH and qRT-PCR (P < 0.05), demonstrating a synergistic effect of RGNNV and V. harveyi in grouper. Furthermore, we found that V. harveyi inhibited the induction and migration of neutrophils by RGNNV, resulting the obviously reduced neutrophils of co-infection groups (P < 0.05). In addition, transcriptome analysis showed that differentially expressed genes (DEGs) of brain tissues of different experimental groups were enriched in immune signaling pathways, such as JAK-STAT signaling, NF-κB signaling and TNF signaling pathways. For the liver and spleen tissues, the DEGs of different experimental groups were enriched in metabolism-related pathways, such as glycolysis/gluconeogenesis and glycerolipid metabolism. Further analysis of the selected DEGs, co-infection of RGNNV and V. harveyi significantly suppressed the host immune response and up-regulated host glucose and lipid metabolism, compared with single-pathogen infection. Taken together, the RGNNV and V. harveyi make synergic reaction in grouper, possibly due to the down regulation of host immune response and up regulation of metabolism to facilitate the replication of both pathogens. These results provide new insights into the pathogenesis of multiple pathogens, and contribute to develop new therapies.

Secondary Neutropenias

Neutrophils are a critical component of immunity, particularly against bacteria and other pathogens, but also in inflammation and tissue repair. As a consequence, individuals with neutropenia, defined by a reduction in absolute neutrophil counts, exhibit a strong propensity to severe infections that typically present with muted symptoms. Neutropenias encompass a heterogeneous set of disorders, comprising primary neutropenias, in which specific genes are mutated, and the more common secondary neutropenias, which have diverse non-genetic causes. These include hematological and other cancers, involving both direct effects of the cancer itself and indirect impacts via the chemotherapeutic, biological agents and cell-based approaches used for treatment. Other significant causes of secondary neutropenias are non-chemotherapeutic drugs, autoimmune and other immune diseases, infections and nutrient deficiencies. These collectively act by impacting neutrophil production in the bone marrow and/or destruction throughout the body. This review describes the biological and clinical manifestations of secondary neutropenias, detailing their underlying causes and management, with a discussion of alternative and emerging therapeutic approaches.

T cell and autoantibody profiling for primary immune regulatory disorders

Background

Limited clinical tools exist for characterizing primary immune regulatory disorders (PIRD), which are often diagnoses of exclusion. Increased CD4+CXCR5+PD1+ circulating T follicular helper (cTfh) cell percentages have been identified as a marker of active disease in some, but not all, autoimmune disorders.

Objective

To develop a diagnostic approach that combines measurements of cellular and serologic autoimmunity.

Methods

We recruited 71 controls and 101 pediatric patients with PIRD with autoimmunity. Flow cytometry was used to measure CD4+CXCR5+ T cells expressing the chemokine receptors CXCR3 and/or CCR6. IgG and IgA autoantibodies were quantified in 56 patients and 20 controls using a microarray featuring 1616 full-length, conformationally intact protein antigens. The 97.5th percentile in the controls serves as the upper limit of normal for percentages of cTfh cells, CD4+CXCR5+ T cells expressing CXCR3 and/or CCR6, and autoantibody intensity and number.

Results

We found that 27.7% of patients had increased percentages of CD4+CXCR5+PD1+ cTfh cells and 42.5% had increased percentages of CD4+CXCR5+ cells expressing CXCR3 and/or CCR6. Patients had significantly more diverse IgG and IgA autoantibodies than controls and 37.5% had increased numbers of high-titer autoantibodies. Integrating measurements of cTfh cells, CD4+CXCR5+ T cells with CXCR3 and/or CCR6, and numbers of high-titer autoantibodies had 71.4% sensitivity (95% CI: 0.5852 - 0.8158) and 85% specificity (95% CI: 0.6396 - 0.9476) for patients with PIRD compared to controls.

Conclusion

By integrating CD4+ T cell phenotyping and total burden of autoantibodies, this approach provides additional tools for the diagnosis of PIRD lacking clinical diagnostic criteria.

A Case of Autoimmune Neutropenia That Responded to Rituximab

Autoimmune neutropenia (AIN) refers to the immune-mediated destruction of neutrophils. It is a rare condition with an estimated prevalence of less than 1 case per 100,000 per year. Typical treatment involves supportive care with granulocyte colony-stimulating factor (G-CSF) and management of secondary infections with antibiotics. Other therapies targeted at the immune system such as steroids, intravenous immunoglobulin (IVIG), and rituximab have not been thoroughly evaluated, but recently rituximab has shown promising results in one case series. We present a 76-year-old man with the diagnosis of antineutrophil antibody-negative AIN and concurrent immune thrombocytopenic purpura (ITP), whose AIN was treated initially with G-CSF which had a short-lived effect, then treated with rituximab which induced a lasting remission. We then review this case in context of other cases described in the literature, given the paucity of available publications.

Chronic neutropenia in childhood: experience of a tertiary center

OBJECTIVE

To assess the prevalence of chronic neutropenia (CN) and the clinical profile of patients with CN aged up to 18 years, followed in the pediatric hematology, rheumatology, or immunology outpatient clinic of a tertiary medical center from May 1, 2018, to 30 April 2019.

METHODS

Retrospective observational study carried out by collecting data from the patient's medical charts. CN was defined as absolute neutrophil count (ANC) below 1.5 × 109/L lasting over three months. Autoimmune neutropenia (AIN) was defined by clinical criteria and an over twofold increase in ANC after glucocorticoid stimulation. AIN was considered secondary when associated with autoimmune or immunoregulatory disorders. Wilcoxon and Fisher's exact tests were used to compare variables; the significance level was 5 %.

RESULTS

A total of 1,039 patients were evaluated; 217 (20 %) presented CN. Twenty-one (2 %) had AIN, classified as primary in 57 % of the cases. The average age at the onset of symptoms was 38.6 months. During follow-up, patients had 4.2 infections on average; frequency was higher among patients with secondary AIN (p = 003). Isolated neutropenia occurred in 43 % of the patients with AIN. Neutropenia resolved in eight (38 %) of the 21 patients with AIN within 19.6 months on average. Eight patients with secondary AIN met the criteria for Inborn Errors of Immunity.

CONCLUSION

AIN prevalence was 2 %. Most cases were first evaluated by a pediatric immunologist or rheumatologist rather than a pediatric hematologist. This study highlights the need for a multidisciplinary approach involving a pediatric immunologist, rheumatologist, and hematologist.

Bi-isotype immunoglobulins enhance antibody-mediated neutrophil activity against Plasmodium falciparum parasites

Background

Malaria remains a major global health priority, and monoclonal antibodies (mAbs) are emerging as potential new tools to support efforts to control the disease. Recent data suggest that Fc-dependent mechanisms of immunity are important mediators of protection against the blood stages of the infection, but few studies have investigated this in the context of mAbs. We aimed to isolate mAbs agnostic to cognate antigens that target whole merozoites and simultaneously induce potent neutrophil activity measured by the level of reactive oxygen species (ROS) production using an antibody-dependent respiratory burst (ADRB) assay.

Methods

We used samples from semi-immune adults living in coastal Kenya to isolate mAbs that induce merozoite-specific ADRB activity. We then tested whether modifying the expressed IgG1 isotype to an IgG-IgA Fc region chimera would enhance the level of ADRB activity.

Results

We isolated a panel of nine mAbs with specificity to whole merozoites. mAb J31 induced ADRB activity in a dose-dependent fashion. Compared to IgG1, our modified antibody IgG-IgA bi-isotype induced higher ADRB activity across all concentrations tested. Further, we observed a negative hook effect at high IgG1 mAb concentrations (i.e., >200 µg/mL), but this was reversed by Fc modification. We identified MSP3.5 as the potential cognate target of mAb J31.

Conclusions

We demonstrate an approach to engineer mAbs with enhanced ADRB potency against blood-stage parasites.

Dying to Defend: Neutrophil Death Pathways and their Implications in Immunity

Neutrophils, accounting for ≈70% of human peripheral leukocytes, are key cells countering bacterial and fungal infections. Neutrophil homeostasis involves a balance between cell maturation, migration, aging, and eventual death. Neutrophils undergo different death pathways depending on their interactions with microbes and external environmental cues. Neutrophil death has significant physiological implications and leads to distinct immunological outcomes. This review discusses the multifarious neutrophil death pathways, including apoptosis, NETosis, pyroptosis, necroptosis, and ferroptosis, and outlines their effects on immune responses and disease progression. Understanding the multifaceted aspects of neutrophil death, the intersections among signaling pathways and ramifications of immunity will help facilitate the development of novel therapeutic methods.

A Case of Late-Onset Neutropenia in Relapsing-Remitting Multiple Sclerosis Following Ocrelizumab Therapy

Ocrelizumab, a monoclonal antibody, has proven effective in treating both primary progressive and relapsing-remitting multiple sclerosis. Common adverse effects observed in clinical studies include flushing, sore throat, pruritus, and rash. This abstract discusses a case of severe, late-onset neutropenia in a patient with relapsing-remitting multiple sclerosis undergoing ocrelizumab treatment. The neutropenia emerged 46 days following the patient's most recent ocrelizumab dose. The patient responded well to treatment with intravenous meropenem and filgrastim. This rare and unforeseen adverse effect highlights the importance of regular blood monitoring for early detection of severe neutropenia in patients treated with ocrelizumab.

BPI23-Fcγ alleviates lethal multi-drug-resistant Acinetobacter baumannii infection by enhancing bactericidal activity and orchestrating neutrophil function

Antibiotic resistance has become a major threat, contributing significantly to morbidity and mortality globally. Administering non-antibiotic therapy, such as antimicrobial peptides, is one potential strategy for effective treatment of multi-drug-resistant Gram-negative bacterial infections. Bactericidal/permeability-increasing protein (BPI) derived from neutrophils has bactericidal and endotoxin-neutralizing activity. However, the protective roles and mechanisms of BPI in multi-drug-resistant bacterial infections have not been fully elucidated. In this study, a chimeric BPI23-Fcγ recombined protein comprising the functional N terminus of BPI and Fcγ was constructed and expressed by adenovirus vector 5 (Ad5). Ad5-BPI23-Fcγ or recombinant BPI23-Fcγ protein significantly improved the survival of mice with pneumonia induced by a minimal lethal dose of multi-drug-resistant Acinetobacter baumannii or Klebsiella pneumoniae by ameliorating lung pathology and reducing pro-inflammatory cytokines. Transfection with Ad5-BPI23-Fcγ significantly decreased the bacterial load and endotoxaemia, which was associated with enhanced bactericidal ability and elevated the phagocytic activity of neutrophils in vitro and in vivo. In addition, Ad5-BPI23-Fcγ transfection significantly increased the recruitment of neutrophils to lung, increased the proportion and number of neutrophils in peripheral blood, and promoted the maturation of bone marrow (BM) neutrophils after drug-resistant A. baumannii infection. BPI23-Fcγ and neutrophils synergistically enhanced bactericidal activity and decreased pro-inflammatory cytokines. These results demonstrated that the chimeric BPI23-Fcγ protein protected mice from pneumonia induced by multi-drug-resistant A. baumannii infection by direct bactericidal effects and promotion of neutrophil recruitment, phagocytosis and maturation. Chimeric BPI23-Fcγ may be a promising candidate as a non-antibiotic biological agent for multi-drug-resistant A. baumannii infection.

Isolation methods determine human neutrophil responses after stimulation

Studying neutrophils is challenging due to their limited lifespan, inability to proliferate, and resistance to genetic manipulation. Neutrophils can sense various cues, making them susceptible to activation by blood collection techniques, storage conditions, RBC lysis, and the isolation procedure itself. Here we assessed the impact of the five most used methods for neutrophil isolation on neutrophil yield, purity, activation status and responsiveness. We monitored surface markers, reactive oxygen species production, and DNA release as a surrogate for neutrophil extracellular trap (NET) formation. Our results show that neutrophils isolated by negative immunomagnetic selection and density gradient methods, without RBC lysis, resembled untouched neutrophils in whole blood. They were also less activated and more responsive to milder stimuli in functional assays compared to neutrophils obtained using density gradients requiring RBC lysis. Our study highlights the importance of selecting the appropriate method for studying neutrophils, and underscores the need for standardizing isolation protocols to facilitate neutrophil subset characterization and inter-study comparisons.

Clinical significance of human neutrophil antigen-1 antibodies in children with neutropenia

Primary autoimmune neutropenia in young children is characterized by chronic neutropenia and positivity for antibodies against human neutrophil antigens (HNAs). This study analyzed the clinical characteristics of 402 children with neutropenia to identify differences between those with and without HNA-1 antibodies (HNA1abs). HNAabs in sera were detected by granulocyte immunofluorescence testing using flow cytometry. Relative fluorescence intensity (RFI) values were used to divide patients into positive (PG, n = 302), borderline (BG, n = 34), and negative (NG, n = 66) groups. The antibodies reacted to HNA-1a alone (59%), HNA-1b alone (1%), and HNA-1a/1b (40%). The PG had a significantly lower absolute neutrophil count before definitive diagnosis and a 1.6- to 2-times greater risk of hospitalization during neutropenia than the other groups. The median duration of neutropenia was longest in the PG at 25 months, followed by 20 months in the BG and 14 months in the NG. This large-scale cohort characterizes clinically distinct groups using the RFI value for HNA1abs in young children with neutropenia. Detection of HNA1abs may aid in understanding the clinical characteristics of children with neutropenia.

Mycobacterium tuberculosis in a Trap: The Role of Neutrophil Extracellular Traps in Tuberculosis

Mycobacterium tuberculosis complex causes tuberculosis (TB), a disease that causes pulmonary inflammation but can also affect other tissues. Despite macrophages having a defined role in TB immunopathogenesis, other innate immune cells, such as neutrophils, are involved in this process. These cells have high phagocytic ability and a microbial-killing machine comprised of enzymes, antimicrobial peptides, and reactive oxygen species. In the last two decades, a new neutrophil immune response, the neutrophil extracellular traps (NETs), has been intensely researched. NETs comprise DNA associated with histones, enzymes, and antimicrobial peptides. These structures are related to antimicrobial immune response and some immuno-pathogenesis mechanisms. This mini review highlights the role of NETs in tuberculosis and how they can be helpful as a diagnostic tool and/or therapeutic target.

The promise of novel treatments for severe chronic neutropenia

INTRODUCTION

Severe chronic neutropenia, i.e. absolute neutrophil count (ANC) less than 0.5 × 109/L, is a serious health problem because it predisposes patients to recurrent bacterial infections. Management radically changed with the discovery that granulocyte colony-stimulating factor (G-CSF) could be used to effectively treat most patients; therapy required regular subcutaneous injections. In the early days of G-CSF therapy, there were concerns that it might somehow overstimulate the bone marrow and cause myelodysplasia (MDS) or acute myeloid leukemia (AML). Detailed research records from the Severe Chronic Neutropenia International Registry (SCNIR) indicate that this is a relatively low-risk event. The research records suggest that certain patient groups are primarily at risk. Presently, allogeneic hematopoietic stem cell therapy serves as an alternate form of therapy.

AREAS COVERED

Due to these concerns and the desire for an easy-to-take oral alternative, several new treatments are under investigation. These treatments include neutrophil elastase inhibitors, SGLT-2 inhibitors, mavorixafor - an oral CXCR4 inhibitor, gene therapy, and gene editing.

EXPERT OPINION

All of these alternatives to G-CSF are promising. The risks, relative benefits, and costs are yet to be determined.

Value-Based Care for Healthy Children With First Episode of Febrile Neutropenia

OBJECTIVES

There is a lack of guidance on the management of febrile neutropenia in otherwise healthy children, including the need for hospitalization and antibiotic administration, leading to significant practice variation in management. The aim of this initiative was to decrease the number of unnecessary hospitalizations and empirical antibiotics prescribed by 50% over a 24-month period for well-appearing, previously healthy patients older than 6 months presenting to the emergency department with a first episode of febrile neutropenia.

METHODS

A multidisciplinary team of stakeholders was assembled to develop a multipronged intervention strategy using the Model for Improvement. A guideline for the management of healthy children with febrile neutropenia was created, coupled with education, targeted audit and feedback, and reminders. Statistical control process methods were used to analyze the primary outcome of the percentage of low-risk patients receiving empirical antibiotics and/or hospitalization. Balancing measures included missed serious bacterial infection, emergency department (ED) return visit, and a new hematologic diagnosis.

RESULTS

Over the 44-month study period, the mean percentage of low-risk patients hospitalized and/or who received antibiotics decreased from 73.3% to 12.9%. Importantly, there were no missed serious bacterial infections, no new hematologic diagnoses after ED discharge, and only 2 ED return visits within 72 hours without adverse outcomes.

CONCLUSIONS

A guideline for the standardized management of febrile neutropenia in low-risk patients increases value-based care through reduced hospitalizations and antibiotics. Education, targeted audit and feedback, and reminders supported sustainability of these improvements.

The European Guidelines on Diagnosis and Management of Neutropenia in Adults and Children: A Consensus Between the European Hematology Association and the EuNet-INNOCHRON COST Action

Neutropenia, as an isolated blood cell deficiency, is a feature of a wide spectrum of acquired or congenital, benign or premalignant disorders with a predisposition to develop myelodysplastic neoplasms/acute myeloid leukemia that may arise at any age. In recent years, advances in diagnostic methodologies, particularly in the field of genomics, have revealed novel genes and mechanisms responsible for etiology and disease evolution and opened new perspectives for tailored treatment. Despite the research and diagnostic advances in the field, real world evidence, arising from international neutropenia patient registries and scientific networks, has shown that the diagnosis and management of neutropenic patients is mostly based on the physicians' experience and local practices. Therefore, experts participating in the European Network for the Innovative Diagnosis and Treatment of Chronic Neutropenias have collaborated under the auspices of the European Hematology Association to produce recommendations for the diagnosis and management of patients across the whole spectrum of chronic neutropenias. In the present article, we describe evidence- and consensus-based guidelines for the definition and classification, diagnosis, and follow-up of patients with chronic neutropenias including special entities such as pregnancy and the neonatal period. We particularly emphasize the importance of combining the clinical findings with classical and novel laboratory testing, and advanced germline and/or somatic mutational analyses, for the characterization, risk stratification, and monitoring of the entire spectrum of neutropenia patients. We believe that the wide clinical use of these practical recommendations will be particularly beneficial for patients, families, and treating physicians.

Neutrophil intrinsic and extrinsic regulation of NETosis in health and disease

Neutrophil extracellular traps (NETs) evolved to protect the host against microbial infections and are formed by a web-like structure of DNA that is decorated with antimicrobial effectors. Due to their potent inflammatory functions, NETs also cause tissue damage and can favor and/or aggravate inflammatory diseases. This multipronged activity of NETs requires that the induction, release, and degradation of NETs are tightly regulated. Here we describe the key pathways that are intrinsic to neutrophils and regulate NETosis, and we review the most recent findings on how neutrophil extrinsic factors participate in the formation of NETs. In particular, we emphasize how bystander cells contribute to modifying the capacity of neutrophils to undergo NETosis. Finally, we discuss how these neutrophil extrinsic processes can be harnessed to protect the host against the excessive inflammation elicited by uncontrolled NET release.

Resource Use and Costs Related to Hematological Complications of Chemotherapy: Cost of Illness Study Based on Data from Balkan Country with Recent History of Socioeconomic Transition

Background

The administration of chemotherapy positively correlates with diverse adverse drug reactions, including the significant impact of hematological hazards such as anemia, leukopenia-neutropenia, thrombocytopenia, and pancytopenia. This pilot pharmacoeconomic study aimed to estimate the total direct costs of treating hematological toxicity induced by chemotherapy and its main determinants.

Methods

The study was conducted as a retrospective cost of illness study using the "from bottom to the top" approach from the perspective of the Republic Health Insurance Fund. This study included 88 patients treated due to developing at least one episode of one of the types of hematological complications of cytostatics in 2018 at the Oncology Clinic of the University Clinical Center Kragujevac, Kragujevac, the Republic of Serbia.

Results

Among cancer patients who developed haematological toxicity, treating pancytopenia was most demanding in a pharmacoeconomic manner compared to neutropenia and thrombocytopenia, with an estimated value of direct costs of 264,14, 178,19 and 157,76 euros per patient per year respectively. Regarding total direct costs, the main determinants were the costs of drugs, their parenteral administration, and costs due to hospitalization.

Conclusion

Due to the rising cancer incidence and obligatory hospital treatment of hematological toxicity induced by chemotherapy, the identification of the pharmacoeconomic aspects of the treatment of these complications is needed. Future research should focus on the development of new modalities of treatment regarding patient characteristics anticipating high costs.

Pediatric Benign Neutropenia: Assessing Practice Preferences in Canada

Pediatric benign neutropenia is a self-limited condition with a benign clinical course. An approach to this condition is not well-defined in the literature. Our objective was to use a case-based survey to elucidate trends in the diagnosis and management of benign neutropenia among pediatric hematology/oncology practitioners in Canada. We received 46 completed surveys (response rate 66%). At initial presentation with fever and neutropenia, 67% of respondents recommended partial septic workup but 11% recommended no investigations. Nearly 70% recommended admission for empiric intravenous antibiotics, while 24% would discharge home without antibiotics. In a patient with fever and known neutropenia, respondents were more likely to pursue outpatient antibiotic therapy. For investigation of chronic neutropenia, most respondents (60%) do not use antineutrophil antibody testing. Common indications for bone marrow biopsy were severe infection, prolonged neutropenia, or before initiating granulocyte colony stimulating factor. Indications for granulocyte colony stimulating factor were based on severity and frequency of infection. Most respondents (84%) would not recommend antibiotic prophylaxis. Results demonstrate the considerable variability in management of benign neutropenia among pediatric hematology/oncology practitioners in Canada and highlight the need for prospective studies to establish diagnostic criteria for benign neutropenia and evaluate management of fever in this population.

Neutropenia in Patients With Clozapine-Treated Schizophrenia: An Effect of Clozapine or a Consequence of SARS-CoV-2 Infection? A Systematic Review

BACKGROUND

Clozapine is the only approved antipsychotic for treatment-resistant schizophrenia. Despite its therapeutic benefits, it is still widely underused, mainly because of its potential to cause agranulocytosis and neutropenia. Prescribing clozapine in COVID-19-positive patients became more challenging because of this potential side effect. This article is a review of literature on the risk of neutropenia associated with clozapine treatment in patients with COVID-19.

AREAS OF UNCERTAINTY

In clozapine-treated COVID-19-positive patients, neutropenia was reported in some cases; is it a consequence of clozapine treatment or of SARS-Co2 infection?

DATA SOURCES

Data were extracted from 2 databases: PubMed/MEDLINE and Google Scholar. We selected all original reports, from March 2020 until May 2022, on neutropenia associated with clozapine treatment in positive COVID-19 patients. Eleven studies were selected for the final analysis.

THERAPEUTIC ADVANCES

Before the COVID-19 pandemic, neutropenia in clozapine-treated patients was reported in 3.8% of cases. During the pandemic, neutropenia rates seemed to be higher. As per the cause of neutropenia, studies reported contradictory results. We aim to clarify rates and causes of neutropenia in clozapine-treated COVID-19-positive patients.

RESULTS

Three hundred eighty-eight articles were initially selected from the 2 databases. After excluding duplicates, unrelated articles, reviews, and guidelines, 11 studies were analyzed, all centered on clozapine treatment, COVID-19 infection, and associated neutropenia.

CONCLUSIONS

Clozapine treatment in COVID-19-positive patients may be associated with a transient reduction of absolute neutrophils count, in some cases reaching neutropenia levels. Neutropenia rates reported in SARS-CoV-2-infected patients are higher than the prepandemic reports; therefore, we assume that the cause might be a result of the immunological interference between clozapine and SARS-CoV-2. Clozapine treatment needs to be continued whenever possible, with dose adjustments in relation to blood test results.

The role of neutrophils in antibody-driven autoimmune cytopenias

Autoimmune cytopenias are a consequence of autoantibodies that target blood cell lineages and mark them for their accelerated destruction, mostly through phagocytosis by monocytes and macrophages and complement activation. Neutrophils, although equipped with Fc and complement receptors and effector mechanisms that are critical in other autoimmune conditions, remained long overlooked. Recent reports, however, propose a new and possibly critical role of neutrophils. In this review, we gathered available evidence on the contribution of neutrophils to the development, onset, and consequences of autoantibody-dependent cytopenias.

Outcomes for patients with severe chronic neutropenia treated with granulocyte colony-stimulating factor

Severe chronic neutropenia (SCN), defined as blood neutrophils < 0.5 x 109/L for more than 3 months, is an uncommon hematological condition associated with recurrent and severe bacterial infections. After short-term clinical trials showed the benefits of granulocyte colony-stimulating factor (G-CSF) treatment for SCN, the Severe Chronic Neutropenia International Registry (SCNIR) opened to determine the long-term benefits and safety of this treatment. This report summarizes findings from more than 16 000 patient-years of prospective observations for patients with congenital and acquired SCN. We observed that adverse outcomes depend on the underlying etiology. MDS and AML occur infrequently and largely in patients with congenital neutropenias. Having cyclic or chronic autoimmune/idiopathic neutropenia portends a favorable prognosis. A few patients with idiopathic neutropenia evolve to develop lymphoid malignancies, but they do not appear to be at increased risk of myeloid malignancies, even with very long-term G-CSF therapy. Progression to systemic autoimmune diseases, bone marrow failure, aplastic anemia, or non-myeloid malignancies are not expected consequences of SCN or treatment with G-CSF.

Clozapine and Neutropenia in Patients with Schizophrenia and SARS-CoV-2 Infection

BACKGROUND

Clozapine (CLZ) is used for treatment-resistant schizophrenia (TRS). Adverse reactions to clozapine include neutropenia. In March 2020, WHO declared the COVID-19 pandemic and after, psychiatrists raised concerns regarding continuation of clozapine, due to multiple restrictions. We aimed to provide a study on the association between neutropenia and clozapine in patients with schizophrenia and COVID-19.

AIM

To assess the neutrophil count in patients with schizophrenia treated with clozapine and infected with COVID-19.

METHODS

The study patients with schizophrenia, according to DSM-5, admitted to the Clinical Hospital of Psychiatry and Neurology Brasov, Romania, between April 2020 and October 2021. The inclusion criteria included positive RT-PCR (real-time PCR) test for COVID-19 and treatment with clozapine. We assessed three values of ANC (absolute neutrophil count): before COVID-19 infection (last ANC obtained at mandatory check), during infection and 1 month after resolution (first negative PCR test).

RESULTS

Of the 105 cases, 95 did not have neutropenia. Fifty-nine patients were males (62.1%), mean age was 43.5 years (SD = 12.1) with an average of clozapine treatment of 52.4 months (SD = 11.9). At baseline, they had a small reduction in the ANC mean value (4.41 × 109/l; SD = 2.22) which did not constitute a statistically significant decline from the prior to COVID-19 mean value of 4.66 × 109/l (SD = 2.34; p = 0.45). Values were also normal in the first month after negative PCR testing (4.45 × 109/l; SD = 2.35; p = 0.91). A total of 10 patients (9.5%) had neutropenia. The age, dose of clozapine and duration of treatment were not statistically different compared to the group without neutropenia.

CONCLUSION

Psychiatrists and other health professionals should keep in mind that neutrophil count may decrease during COVID-19 infection in patients taking clozapine and in some cases, neutropenia may even occur. We assumed that neutropenia could be caused by COVID-19 and clozapine interaction.

Severe late-onset neutropenia induced by ocrelizumab in a multiple sclerosis patient: A case report

Ocrelizumab is a recombinant humanized antibody targeted against CD-20 molecule, which was approved for the treatment of relapsing and primary progressive multiple sclerosis. Common adverse events of ocrelizumab include infusion-related reactions like rash, pruritus, and flushing. Late-onset neutropenia (LON) is a rarely reported complication of ocrelizumab therapy. We report a case of severe late-onset neutropenia in a patient with primary progressive multiple sclerosis treated with ocrelizumab with neutropenia occurring 3 months after the last dose received treated with empirical broad-spectrum intravenous antibiotics and filgrastim. Severe late-onset neutropenia is a rare unpredictable adverse event and outlines the importance of regular routine blood workup for detecting severe neutropenia early in its course.

Diagnosis and therapeutic decision-making for the neutropenic patient

Determining the cause of a low neutrophil count in a pediatric or adult patient is essential for the hematologist's clinical decision-making. Fundamental to this diagnostic process is establishing the presence or lack of a mature neutrophil storage pool, as absence places the patient at higher risk for infection and the need for supportive care measures. Many diagnostic tests, eg, a peripheral blood smear and bone marrow biopsy, remain important tools, but greater understanding of the diversity of neutropenic disorders has added new emphasis on evaluating for immune disorders and genetic testing. In this article, a structure is provided to assess patients based on the mechanism of neutropenia and to prioritize testing based on patient age and hypothesized pathophysiology. Common medical quandaries including fever management, need for growth factor support, risk of malignant transformation, and curative options in congenital neutropenia are reviewed to guide medical decision-making in neutropenic patients.

The Neutrophil

Neutrophils are immune cells with unusual biological features that furnish potent antimicrobial properties. These cells phagocytose and subsequently kill prokaryotic and eukaryotic organisms very efficiently. Importantly, it is not only their ability to attack microbes within a constrained intracellular compartment that endows neutrophils with antimicrobial function. They can unleash their effectors into the extracellular space, where, even post-mortem, their killing machinery can endure and remain functional. The antimicrobial activity of neutrophils must not be misconstrued as being microbe specific and should be viewed more generally as biotoxic. Outside of fighting infections, neutrophils can harness their noxious machinery in other contexts, like cancer. Inappropriate or dysregulated neutrophil activation damages the host and contributes to autoimmune and inflammatory disease. Here we review a number of topics related to neutrophil biology based on contemporary findings.

Considerations of HLA, Renal Failure, Valproic Acid Use, and Current Treatment Guidelines in Clozapine-Induced Agranulocytosis

Clozapine, the choice atypical antipsychotic for refractory schizophrenia, schizoaffective disorder, and bipolar disorder, has been shown to reduce positive and negative symptoms of schizophrenia. Clozapine, though beneficial in reducing the need for hospitalization, rehabilitation, and health care costs, is known as a drug of last resort due to its potential adverse event of clozapine-induced agranulocytosis, which holds a case fatality rate between 4.2 and 16%. Herein, we describe a female patient with longstanding schizoaffective disorder and chronic kidney disease who suffered from clozapine-induced agranulocytosis after failing two other atypical antipsychotics. Retrospective considerations of this case and management highlight risk factors such as HLA status, renal failure, and concurrent valproic acid use which presently do not have official screening, guidelines, or restrictions in place when prescribing clozapine. Additionally, there are no specific clozapine-induced agranulocytosis management recommendations such as G-CSF/filgrastim dose, timing of bone marrow aspirate and biopsy, and use of concomitant valproate. We propose that further comprehensive official screening, monitoring, and guidelines in the prescribing of clozapine, and further guidelines in the treatment of clozapine induced agranulocytosis, could increase the cost-effectiveness of clozapine treatment, and decrease the incidence, and morbidity of this feared adverse event.

Are Patients With Autoimmune Cytopenias at Higher Risk of COVID-19 Pneumonia? The Experience of a Reference Center in Northern Italy and Review of the Literature

During COVID-19 pandemic the care of onco-hematologic and autoimmune patients has raised the question whether they are at higher risk of infection and/or worse outcome. Here, we describe the clinical course of COVID-19 pneumonia in patients with autoimmune cytopenias (AIC) regularly followed at a reference center in Northern Italy. The study period started from COVID-19 outbreak (February 22, 2020) until the time of writing. Moreover, we provide a review of the literature, showing that most cases reported so far are AIC developed during or secondary to COVID-19 infection. At variance, data about AIC pre-existing to COVID infection are scanty. The 4 patients here described (2 autoimmune hemolytic anemias, AIHA, 1 Evans syndrome, and 1 immune thrombocytopenia) with COVID-19 pneumonia belong to a large cohort of 500 AIC patients, making this study nearly population-based. The observed frequency (4/501; 0.7%) is only slightly superior to that of the general population admitted to hospital/intensive care unit (0.28/0.03%, respectively) in Lombardy in the same period of observation. All cases occurred between March 21 and 25, whilst no more AIC were recorded later on. Although different in intensity of care needed, all patients recovered from COVID-19 pneumonia, with apparently no detrimental effect of previous/current immunomodulatory treatments. AIHA relapse occurred in two patients, but promptly responded to therapy. With limitations due to sample size, these results suggest a favorable outcome and a lower-than-expected incidence of COVID-19 pneumonia in patients with previously diagnosed AIC, and allow speculating that immunomodulatory drugs used for AIC may play a beneficial rather than a harmful effect on COVID-19 infection.

Primary autoimmune neutropenia of infancy and childhood in a cohort of patients from western Romania

Neutropenia is commonly diagnosed in pediatric clinics. Due to the special vulnerability of neutropenic patients, the assessment of the etiopathogenic background of neutropenia is mandatory. In this retrospective cross-sectional cohort study, we aimed to establish the status of primary autoimmune neutropenia (AIN) from the point of view of its clinical and biological features and its outcome in a cohort of pediatric patients. We recorded all of the 3,488 cases consecutively admitted to our hospital for different diagnoses but presenting neutropenia, during a period of 3 years (January 2016 to December 2018). We had to exclude 224 patients from the analysis due to incomplete data. Our study focused on patients with AIN or chronic benign neutropenia of infancy and childhood. In these patients, a granulocyte antibody screening by granulocyte immunofluorescence test (GIFT) and the granulocyte agglutination test (GAT) were performed. Regarding their pathogenic background, 0.1% of the patients presenting neutropenia were congenital forms, the rest being acquired forms. Primary AIN was encountered in 18 cases, representing approximately 0.5%. The median age at onset for primary AIN was 7.5 months. Male/female ratio in AIN was 1.94. In 72% of the patients with AIN, neutropenia was severe during the course of disease. In 3 patients, both GIFT and GAT were positive and in 8 patients, only GIFT was positive. For the remaining 7 patients (39%), both GIFT and GAT revealed negative results. 50% of the patients needed hospitalization, but only 3 patients presented severe infections. On-demand G-CSF was administered in 22% of the patients. Our study provides insight with regard to neutropenia, showing the high frequency and etiological diversity in childhood. Primary AIN is usually diagnosed by exclusion of the other causes of neutropenia. GIFT and GAT are useful, but rarely available diagnostic tools for the confirmation of primary AIN.

Neutropenia Is Not Associated With the Outcomes in Patients With Kawasaki Disease

Objective: To investigate the outcomes of coronary artery lesions (CALs) and intravenous immunoglobulin (IVIG) resistance in patients with and without neutropenia during the disease course and to explore the relationships between Δ absolute neutrophils count (ΔANC) and the outcomes. Methods: We retrospectively reviewed the medical records of patients hospitalized in Children's Hospital of Soochow University with a main diagnosis of KD during January 2019 and December 2019. 1:4 propensity score matching was carried out to adjust the baseline characteristics. Smoothed plots and threshold effect analyses were performed to reveal the relationships between ΔANC and the outcomes. Results: Of the 438 patients enrolled, 75 (17.1%) were neutropenia cases and 363 (82.9%) were non-neutropenia cases. Patients with neutropenia were younger, had lower levels of initial ANC, white blood cell (WBC) count and C-reactive protein (CRP). Propensity score matching included 75 neutropenia and 247 non-neutropenia patients. No significant difference was found between neutropenia and non-neutropenia groups regarding CALs, coronary artery aneurysms, irregular coronary lumen, IVIG resistance and days of fever duration. There was a non-linear relationship between ΔANC and IVIG resistance. However, threshold effect analysis showed the incidence of IVIG resistance decreased with increasing ΔANC before the turning point (ΔANC = 1.6) (OR = 0.65, 95% CI = 0.50-0.8.4 P = 0.001). On the other hand, there was a linear relationship between ΔANC and CALs, even after adjusting the confounders (OR = 1.06, 95% CI = 1.02-1.11, P = 0.008). Conclusions: Neutropenia after IVIG was not exactly associated with the outcomes. However, ΔANC was in relation to CALs and IVIG resistance.

Evans' Syndrome: From Diagnosis to Treatment

Evans' syndrome (ES) is defined as the concomitant or sequential association of warm auto-immune haemolytic anaemia (AIHA) with immune thrombocytopenia (ITP), and less frequently autoimmune neutropenia. ES is a rare situation that represents up to 7% of AIHA and around 2% of ITP. When AIHA and ITP occurred concomitantly, the diagnosis procedure must rule out differential diagnoses such as thrombotic microangiopathies, anaemia due to bleedings complicating ITP, vitamin deficiencies, myelodysplastic syndromes, paroxysmal nocturnal haemoglobinuria, or specific conditions like HELLP when occurring during pregnancy. As for isolated auto-immune cytopenia (AIC), the determination of the primary or secondary nature of ES is important. Indeed, the association of ES with other diseases such as haematological malignancies, systemic lupus erythematosus, infections, or primary immune deficiencies can interfere with its management or alter its prognosis. Due to the rarity of the disease, the treatment of ES is mostly extrapolated from what is recommended for isolated AIC and mostly relies on corticosteroids, rituximab, splenectomy, and supportive therapies. The place for thrombopoietin receptor agonists, erythropoietin, immunosuppressants, haematopoietic cell transplantation, and thromboprophylaxis is also discussed in this review. Despite continuous progress in the management of AIC and a gradual increase in ES survival, the mortality due to ES remains higher than the ones of isolated AIC, supporting the need for an improvement in ES management.

The cost of a "benign" condition: Healthcare utilization and infectious outcomes in young children with primary autoimmune neutropenia

BACKGROUND

Autoimmune neutropenia (AIN) is a common cause of chronic neutropenia in childhood. Despite an expected benign clinical course, many patients undergo extensive evaluation. Data on healthcare utilization and rates of bloodstream infections in young patients with AIN are limited.

METHODS

All patients with a diagnosis code of leukopenia, neutropenia, or AIN followed within the outpatient hematology clinic of a single institution from 2014 to 2016 were identified. Patients aged ≤5 years with absolute neutrophil count (ANC) ≤500/µL persisting for ≥3 months, a clinical diagnosis of AIN, and documented resolution of neutropenia were included. Data on clinical management, including infectious outcomes and emergency center (EC) encounters, were collected.

RESULTS

Forty-three patients with AIN (18 male [42%], median age at diagnosis 12 months) met eligibility criteria. Children were followed by hematology for a median duration of 18 (range, 2-85) months. Diagnostic evaluations were variable. Thirty patients (70%) had ≥ 1 EC encounters for evaluation of isolated fever with a total of 113 EC encounters for the overall cohort. Patients with ANC < 500/µL and isolated fever were admitted for observation, which resulted in 24 hospitalizations in 16 patients. Of 138 blood cultures drawn, two were positive, both later determined to be contaminants.

CONCLUSION

At a large tertiary care center, no bloodstream infections were identified in a cohort of 43 children with AIN presenting to the EC for assessment of fever. A less-intensive, more cost-effective management paradigm, which continues to prioritize patient safety, among young children with AIN is needed.

Isolated Chronic and Transient Neutropenia

Neutrophils are a critical part of the body’s defense system to prevent serious bacterial and fungal infections. Neutropenia is a term which is defined by the absolute neutrophil counts (ANC) < 1,500 cells/µL, and it becomes clinically significant when the level falls below 500 cells/µL. The risk of morbidity and mortality increases considerably when the levels fall below 200. In some ethnicities, the neutropenia is chronic and is frequently seen on routine outpatient visits. On the other hand, transient neutropenia is associated with a transient drop in the neutrophil count and many of the underlying causes are reversible. Patients and their families, as well as some clinicians, express great concern for neutropenia, leading to a multitude of tests and emergency room visits. In this review, we discuss the causes of both chronic and transient neutropenia. Also, we have given special emphasis on the mechanism of neutropenia and management of transient neutropenia.

Comparison of Neutropenia Associated with Ceftaroline or Ceftriaxone in Patients Receiving at Least 7 Days of Therapy for Severe Infections

STUDY OBJECTIVE

Ceftarolinefosamil is a cephalosporin with broad clinical utility; however, limited data suggest that prolonged ceftaroline exposure may be associated with neutropenia. The objective was to determine drug and patient factors associated with neutropenia in patients receiving ceftaroline or ceftriaxone for deep-seated infections.

DESIGN

Retrospective, ratio-matched cohort study.

SETTING

Four acute-care hospitals within an urban health care system.

PATIENTS

A total of 176 hospitalized adults who received definitive ceftaroline (44 patients) or ceftriaxone (132 patients) therapy for at least 7 days between January 2013 and April 2017 for any of the following indications: bone and joint infections (BJI), infective endocarditis (IE), or bloodstream infections (BSI).

MEASUREMENTS AND MAIN RESULTS

The primary outcome was development of neutropenia while receiving cephalosporin therapy, defined as an absolute neutrophil count (ANC) <1500 cells/mm3 . Neutropenia severity and patient characteristics were described and compared between the ceftaroline and ceftriaxone groups. The median (interquartile range [IQR]) antibiotic prescription duration was 41 (29-44) days for the ceftaroline group and 40 (28-44) days for the ceftriaxone group (p=0.9). Cephalosporin indications were 112 (64%) BJI, 27 (15%) BSI, 16 (9%) IE, and 21 (12%) multiple infections; ceftaroline was more commonly used in BJI (p=0.03), and ceftriaxone was more commonly used in IE (p=0.01). Neutropenia developed in 16 (9%) patients: 8 (18%) in the ceftaroline group and 8 (6%) in the ceftriaxone group (p=0.03). Median (IQR) onset to neutropenia was 22 (15-28) days, and median (IQR) change in ANC was 2.86 (1.50-4.08) cells/mm3 ; most cases of neutropenia were mild (12 patients [75%]). The median (IQR) time to mild or moderate-severe neutropenia was not significantly different (p=0.68): 22 (14-28) and 22 (21-36) days, respectively. Treatment was discontinued in 4 (25%) patients due to neutropenia. Ceftaroline use was independently associated with neutropenia (adjusted odds ratio 3.2, 95% confidence interval 1.2-10.5) after adjusting for lower body mass index strata (18.5-25 kg/m2 ).

CONCLUSION

Prolonged ceftaroline use was an independent risk factor for developing mild neutropenia. Clinicians should be cognizant of ANC monitoring in scenarios where prolonged ceftaroline courses are prescribed.

Benign ethnic neutropenia

Benign ethnic neutropenia (BEN) is one of the most common causes of chronic neutropenia seen in individuals of African, Middle Eastern and West Indian descent, affecting many individuals worldwide. Despite its prevalence, many physicians are not familiar with this benign condition, resulting in unnecessary evaluation and testing for neutropenia in otherwise healthy individuals. Clinically, patients with BEN are at no increased risk of infection despite their neutropenia. Implications of this condition are highlighted in those patients receiving therapies that have a known side effect of neutropenia, most commonly chemotherapy agents. Studies have suggested that disparities in survival among those patients receiving chemotherapy between patients of European decent and African decent may be attributed to measured neutropenia in these populations, questioning whether BEN could be an influential factor. This review encompasses all aspects of benign ethnic neutropenia, providing information about this condition and helping to guide clinical decision-making as to when an aggressive work up and referral are indicated and when it is appropriate to monitor. Additionally, we review the role of genetic studies in identifying the genes related to BEN, summarize the theories that offer the most accepted mechanisms behind the condition, and address the importance of pursuing larger studies to assess the implication of BEN in oncology patients as well as patients taking neutropenia-causing medications.

White blood cell subpopulation changes and prevalence of neutropenia among Arab diabetic patients attending Dasman Diabetes Institute in Kuwait

BACKGROUND

The effects of diabetes mellitus on the differential white blood cell count are not widely studied in the Arab populations. The objective of this cross-sectional, retrospective study is to assess the influence of chronic diabetes mellitus on white blood cell counts, absolute neutrophil (ANC) and lymphocyte counts (ALC) as well as the prevalence of benign ethnic neutropenia among Arabs attending the Dasman Diabetes Institute (DDI) in Kuwait.

METHODS AND FINDINGS

1,580 out of 5,200 patients registered in the DDI database qualified for our study. Age, gender, HbA1c and creatinine levels, estimated glomerular filtration rate as well as average WBC, ANC and ALC levels, presence of diabetes-associated complications and anti-diabetic medications were analyzed. Our results showed the mean value of the WBC was 7.6 ± 1.93 x 109/L (95% CI: 2.95-17.15). The mean ANC was 4.3 x 109/L (95% CI: 0.97-10.40) and mean ALC was 2.5 x 109/L (95% CI: 0.29-10.80). Neutropenia (ANC: <1.5 x 109/L) was detected in fifteen patients (0.94%). Six patients (0.4%) fulfilled the definition of lymphopenia (ALC < 1 x109/L). Patients with an HbA1c ≥ 7% and those taking at least 3 anti-diabetic medications showed higher values for ANC and ALC. Patients with diabetes-associated neuropathy or nephropathy displayed higher mean ANC values. Our study was limited by overrepresentation of patients over 50 years old compared to those under 50 as well as selection bias given its retrospective nature.

CONCLUSIONS

Our study showed that patients with poorly controlled diabetes displayed higher ANC and ALC levels. In addition, patients with DM-associated complications showed higher ANC levels. This finding would suggest that DM exerts a pro-inflammatory influence on differential WBC counts. Our study also showed that the prevalence of benign ethnic neutropenia was lower than previously reported in other studies.