Diagnosis and Clinical Course of Autoimmune Neutropenia in Infancy: Analysis of 240 Cases

Neutrophil antigen antibodies affect engraftment and secondary graft failure in hematopoietic progenitor cell transplantation

BACKGROUND

Research is limited on the role of antibodies against human neutrophil antigen (HNA) in hematopoietic progenitor cell (HPC) transplantation outcomes.

STUDY DESIGN AND METHODS

A retrospective review was conducted on medical records of patients at the NIH Clinical Center enrolled in six research protocols. This case-control study included 21 patients tested for HNA antibodies from January 2010 to March 2022 who underwent HPC transplantation. In addition, 42 patients following the same research protocols were randomly selected as a control group.

RESULTS

The cumulative incidence of time to neutrophil engraftment was significantly impacted by the patients' anti-HNA status (p = .042), with the patients with anti-HNA experiencing delayed engraftment. Secondary graft failure occurred in 4 out of 42 patients (9.52%; 95% confidence interval [CI]: 3.7-22.1) of the control group, while 5 out of 9 patients (55.5%; 95% CI: 26.7-81.1) with anti-HNA experienced secondary graft failure (p = .005). Furthermore, patients with anti-HNA had a lower proportion (p = .008 for full and p = .002 for partial chimerism) and cumulative incidence (p = .016 for full and p = .010 for partial chimerism) of achieving donor chimerism compared to the control group.

DISCUSSION

The study reveals a potential link between anti-HNA and HPC transplantation outcomes not previously reported. Patients with anti-HNA had a lower proportion and cumulative incidence of achieving donor chimerism. Additionally, anti-HNA status affected the time for neutrophil engraftment, with a slower rate of neutrophil engraftment and increased risk of secondary failure in patients with anti-HNA.

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.

The ouroboros of autoimmunity

Human autoimmunity against elements conferring protective immunity can be symbolized by the 'ouroboros', a snake eating its own tail. Underlying infection is autoimmunity against three immunological targets: neutrophils, complement and cytokines. Autoantibodies against neutrophils can cause peripheral neutropenia underlying mild pyogenic bacterial infections. The pathogenic contribution of autoantibodies against molecules of the complement system is often unclear, but autoantibodies specific for C3 convertase can enhance its activity, lowering complement levels and underlying severe bacterial infections. Autoantibodies neutralizing granulocyte-macrophage colony-stimulating factor impair alveolar macrophages, thereby underlying pulmonary proteinosis and airborne infections, type I interferon viral diseases, type II interferon intra-macrophagic infections, interleukin-6 pyogenic bacterial diseases and interleukin-17A/F mucocutaneous candidiasis. Each of these five cytokine autoantibodies underlies a specific range of infectious diseases, phenocopying infections that occur in patients with the corresponding inborn errors. In this Review, we analyze this ouroboros of immunity against immunity and posit that it should be considered as a factor in patients with unexplained infection.

Inborn errors of immunity with susceptibility to S. aureus infections

Staphylococcus aureus (S. aureus) is a significant human pathogen, in particular in patients with an underlying medical condition. It is equipped with a large variety of virulence factors enabling both colonization and invasive disease. The spectrum of manifestation is broad, ranging from superficial skin infections to life-threatening conditions like pneumonia and sepsis. As a major cause of healthcare-associated infections, there is a great need in understanding staphylococcal immunity and defense mechanisms. Patients with inborn errors of immunity (IEI) frequently present with pathological infection susceptibility, however, not all of them are prone to S. aureus infection. Thus, enhanced frequency or severity of S. aureus infections can serve as a clinical indicator of a specific underlying immunological impairment. In addition, the analysis of immunological functions in patients with susceptibility to S. aureus provides a unique opportunity of understanding the complex interplay between staphylococcal virulence and host immune predisposition. While the importance of quantitatively and qualitatively normal neutrophils is widely known, less awareness exists about the role of specific cytokines such as functional interleukin (IL)-6 signaling. This review categorizes well-known IEI in light of their susceptibility to S. aureus and discusses the relevant associated pathomechanisms. Understanding host-pathogen-interactions in S. aureus infections in susceptible individuals can pave the way for more effective management and preventive treatment options. Moreover, these insights might help to identify patients who should be screened for an underlying IEI. Ultimately, enhanced understanding of pathogenesis and immune responses in S. aureus infections may also be of relevance for the general population.

Discerning clinicopathological features of congenital neutropenia syndromes: an approach to diagnostically challenging differential diagnoses

The congenital neutropenia syndromes are rare haematological conditions defined by impaired myeloid precursor differentiation or function. Patients are prone to severe infections with high mortality rates in early life. While some patients benefit from granulocyte colony-stimulating factor treatment, they may still face an increased risk of bone marrow failure, myelodysplastic syndrome and acute leukaemia. Accurate diagnosis is crucial for improved outcomes; however, diagnosis depends on familiarity with a heterogeneous group of rare disorders that remain incompletely characterised. The clinical and pathological overlap between reactive conditions, primary and congenital neutropenias, bone marrow failure, and myelodysplastic syndromes further clouds diagnostic clarity.We review the diagnostically useful clinicopathological and morphological features of reactive causes of neutropenia and the most common primary neutropenia disorders: constitutional/benign ethnic neutropenia, chronic idiopathic neutropenia, cyclic neutropenia, severe congenital neutropenia (due to mutations in ELANE, GFI1, HAX1, G6PC3, VPS45, JAGN1, CSF3R, SRP54, CLPB and WAS), GATA2 deficiency, Warts, hypogammaglobulinaemia, infections and myelokathexis syndrome, Shwachman-Diamond Syndrome, the lysosomal storage disorders with neutropenia: Chediak-Higashi, Hermansky-Pudlak, and Griscelli syndromes, Cohen, and Barth syndromes. We also detail characteristic cytogenetic and molecular factors at diagnosis and in progression to myelodysplastic syndrome/leukaemia.

Late-onset and long-lasting neutropenias in the young: A new entity anticipating immune-dysregulation disorders

This study identifies a new chronic form of immune neutropenia in the young with or without detectable indirect anti-neutrophil antibodies, characterized by mild/moderate neutropenia low risk of severe infection (14%), tendency to develop autoimmune phenomena over the course of the disease (cumulative incidence of 58.6% after 20 years of disease duration), leukopenia, progressive reduction of absolute lymphocyte count and a T- and B-cell profile similar to autoimmune disorders like Sjogren syndrome, rheumatoid arthritis, and systemic lupus erythematosus (increased HLADR+ and CD3 + TCRγδ cells, reduced T regulatory cells, increased double-negative B and a tendency to reduced B memory cells). In a minority of patients, P/LP variants related to primary immuno-regulatory disorders were found. This new form may fit the group of "Likely acquired neutropenia," a provisional category included in the recent International Guidelines on Diagnosis and Management of Neutropenia of EHA and EUNET INNOCHRON ACTION 18233. The early recognition of this form of neutropenia would help clinicians to delineate better specific monitoring plans, genetic counseling, and potentially targeted therapies.

High-resolution HLA genotyping identifies risk alleles in both class I and II for primary autoimmune neutropenia in early childhood in a Danish cohort

HLA studies in patients with autoimmune neutropenia (AIN) have shown very consistent results for the association with HLA class II alleles at low resolution. This study aimed to examine the association of both HLA class I and class II at high resolution to clarify the contribution of risk alleles to the disease. A total of 107 AIN patients were genotyped for six loci of HLA class I (HLA-A, -B and -C) and class II (HLA-DRB1, -DQB1, and -DPB1) genes by a high-resolution (3-field, 6-digit) analysis and compared with HLA typing of 1000 healthy controls. Compared with the controls, the allele frequencies were significantly higher in AIN patients for A*02:17:01G, C*01:02:01G, DRB1*10:01:01G, DRB1*14:01:01G, DRB1*16:01:01G, DQB1*05:02:01G, and DQB1*05:03:01G but lower significant for C*03:04:01G, DRB1*04:01:01G, DRB1*13:02:01G, DQB1*03:02:01G, and DQB1*06:04:01G. Frequently associated two-locus haplotypes were found to be DRB1*10:01:01G-DQB1*05:01:01G and DRB1*16:01:01G-DQB1*05:02:01G, while the S2 (Q- or D-KRAA) shared epitope (SE) was associated with lower risk. A unique association with HLA alleles was observed between patients with specific anti-HNA-1a antibodies and broad-reacting anti-FcγRIIIb. Anti-HNA-1a antibody-positive patients were associated with C*01:02:01G, DRB1*01:01:01G, DRB1*16:01:01G, DQB1*05:01:01G, DQB1*05:02:01G, DQB1*06:04:01G, and DPB1*10:01:01G; the two-locus haplotypes DRB1*01:01:01G-DQB1*05:01:01G and DRB1*16:01:01G-DQB1*05:02:01G; and the S3P (Q- or R-RRAA) SE. Anti-FcγRIIIb antibody-positive patients were associated with the alleles A*02:17:01G, DRB1*10:01:01G, and DQB1*05:02:01G; the haplotypes DRB1*10:01:01G-DQB1*05:01:01G and DRB1*11:01:02G-DQB1*05:02:01G; and the S3D (DRRAA) SE. The different associations regarding FcγRIIIb antibody specificities could indicate disease heterogeneity.

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.

The Clinical Course of SARS-CoV-2 Infection in Patients With Autoimmune Neutropenia: A Retrospective Case Series Study

Severe acute respiratory syndrome coronavirus 2 infection in children with autoimmune neutropenia may be a cause for concern. In this retrospective study, none of the 24 autoimmune neutropenia cases manifested severe coronavirus disease 2019. We found a significant improvement in neutrophils and a reduction in lymphocytes at post-infection follow-up compared with the median of previous values. We speculate that this paradoxical effect may be due to postinfection immunological phenomena.

World human neutrophil antigens investigation survey

BACKGROUND AND OBJECTIVES

Human neutrophil antigens (HNAs) are categorized into five systems: HNA-1 to HNA-5. Given the importance of neutrophils in immunity, we sought to create awareness of the role of HNA diagnostic services in managing immune neutropenia and transfusion-related acute lung injury. To provide health communities all around the world with access to these services, we conducted a survey to create a directory of these HNA diagnostic services.

MATERIALS AND METHODS

An Excel table-based survey was created to capture information on the laboratory's location and was emailed to 55 individuals with known or possible HNA investigation activity. The collected data were then summarized and analysed.

RESULTS

Of contacted laboratories, the surveys were returned from 23 (38.2%) laboratories; 17 have already established HNA diagnostic (of them 12 were regular participants of the International Granulocyte Immunobiology Workshop [ISBT-IGIW]), 4 laboratories were in the process of establishing their HNA investigation and the remaining 2 responder laboratories, did not conduct HNA investigations. In established laboratories, investigation for autoimmune neutropenia (infancies and adults) was the most frequently requested, and antibodies against HNA-1a and HNA-1b were the most commonly detected.

CONCLUSION

The directory of survey respondents provides a resource for health professionals wanting to access HNA diagnostic services. The present study offers a comprehensive picture of HNA diagnostics (typing and serology), identifying weak points and areas for improvement for the first time. Identifying more laboratories involved in HNA diagnostics with limited access to international societies in the field will globally improve HNA diagnostics.

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.

Genetic variations in low-to-medium-affinity Fcγ receptors and autoimmune neutropenia in early childhood in a Danish cohort

Autoimmune neutropenia (AIN) in early childhood is caused by autoantibodies directed against antigens on the neutrophil membrane and is a frequent cause of neutropenia in children. Association of AIN with Fcγ receptor (FCGR) 3B variants is well described. In this study, we investigate genetic variations in the FCGR locus and copy number variation of FCGR3B. A total of 130 antibody-positive AIN patients, 64 with specific anti-HNA-1a antibodies and 66 with broad-reacting anti-FcγRIIIb antibodies, were genotyped with a multiplex ligation probe assay and compared with healthy controls. Positive findings were confirmed with real-time q-PCR. We determined copy numbers of the FCGR2 and FCGR3 genes and the following SNPs: FCGR2A Q62W (rs201218628), FCGR2A H166R (rs1801274), FCGR2B I232T (rs1050501), FCGR3A V176F (rs396991), haplotypes for FCGR2B/C promoters (rs3219018/rs780467580), FCGR2C STOP/ORF and HNA-1 genotypes in FCGR3B (rs447536, rs448740, rs52820103, rs428888 and rs2290834). Generally, associations were antibody specific, with all associations being representative of the anti-HNA-1a-positive group, while the only association found in the anti-FcγRIIIb group was with the HNA-1 genotype. An increased risk of AIN was observed for patients with one copy of FCGR3B; the HNA genotypes HNA-1a, HNA-1aa or HNA-1aac; the FCGR2A 166H and FCGR2B 232I variations; and no copies of FCGR2B 2B.4. A decreased risk was observed for HNA genotype HNA-1bb; FCGR2A 166R; FCGR2B 232T; and one copy of FCGR2B promoter 2B.4. We conclude that in our Danish cohort, there was a strong association between variation in the FCGR locus and AIN. The findings of different genetic associations between autoantibody groups could indicate the presence of two different disease entities and disease heterogeneity.

Neutropenia in pediatric solid organ transplant

Neutropenia is generally defined as an absolute neutrophil count in the circulation of less than 1500/mm³ and occurs in up to 25%-30% of pediatric solid organ transplant recipients (SOT) within the first year after transplantation. In the SOT population, neutropenia is most often a result of drug-induced bone marrow suppression but can also be secondary to viral infection, nutritional deficiencies, lymphoproliferative infiltrate, and inherited causes. Outcomes for patients with neutropenia vary by degree of neutropenia and type of solid organ transplant. Management of neutropenia should begin by addressing the underlying cause, including reducing or removing medications when appropriate, treating infections, and addressing nutrient deficiencies; however, consultation with an experienced pediatric hematologist and use of granulocyte colony-stimulating factor (G-CSF) may be helpful in some cases. Overall, data on clinical outcomes for G-CSF use remain limited, but observational studies may support its use in patients with infections or severe neutropenia.

Hematologic cytopenia post CAR T cell therapy: Etiology, potential mechanisms and perspective

Chimeric Antigen-Receptor (CAR) T-cell therapies have shown dramatic efficacy in treating relapsed and refractory cancers, especially B cell malignancies. However, these innovative therapies cause adverse toxicities that limit the broad application in clinical settings. Hematologic cytopenias, one frequently reported adverse event following CAR T cell treatment, are manifested as a disorder of hematopoiesis with decreased number of mature blood cells and subdivided into anemia, thrombocytopenia, leukopenia, and neutropenia, which increase the risk of infections, fatigue, bleeding, fever, and even fatality. Herein, we initially summarized the symptoms, etiology, risk factors and management of cytopenias. Further, we elaborated the cellular and molecular mechanisms underlying the initiation and progression of cytopenias following CAR T cell therapy based on previous studies about acquired cytopenias. Overall, this review will facilitate our understanding of the etiology of cytopenias and shed lights into developing new therapies against CAR T cell-induced cytopenias.

Autoantibodies in immunodeficiency syndromes: The Janus faces of immune dysregulation

Immunodeficiency syndromes represent a diverse group of inherited and acquired disorders, characterized by a spectrum of clinical manifestations, including recurrent infections, autoimmunity, lymphoproliferation and malignancy. Autoantibodies against various self-antigens reflect the immune dysregulation underlying these disorders, and could contribute to certain clinical findings, such as susceptibility to opportunistic infections, cytopenia of different hematopoietic lineages, and organ-specific autoimmune diseases. The mechanism of autoantibody production in the context of immunodeficiency remains largely unknown but is likely shaped by both intrinsic genetic aberrations and extrinsic exposures to possible infectious agents. These autoantibodies if harbor neutralizing activities and reach certain levels in the circulation, could disrupt the biological functions of their targets, resulting in specific clinical manifestations. Herein, we reviewed the prevalence of autoantibodies against cytokines, hematopoietic cells and organ-specific antigens in immunodeficiency syndromes and examined their associations with certain clinical findings. Moreover, the potential mechanism of autoantibody production was also discussed. These may shed light on the development of mechanism-based therapies to reset the dysregulated immune system in immunodeficient patients.

Chronic Neutropenia in Childhood: Laboratory and Clinical Features

OBJECTIVES

To describe the clinical characteristics of patients with chronic neutropenia.

METHODS

Data of 36 patients with chronic neutropenia, who were followed up in the authors' clinic between May 2013 and May 2020, were analyzed retrospectively. Patients were diagnosed based on their clinical and laboratory characteristics.

RESULTS

A total of 36 patients (23 females, 13 males) were included in the study. The mean age at diagnosis was 9.85 ± 9.17 mo while the mean follow-up time was 21.83 ± 20.03 mo. The mean absolute neutrophil count (ANC) at admission was 462.5 ± 388.8 cells/mm³ (median = 375 cells/mm³), and the lowest and highest ANC mean was 241.2 ± 262.1 cells/mm³ (median = 125 cells/mm³), and 1362.9 ± 1127.9 cells/mm³ (median = 925 cells/mm³), respectively. Idiopathic neutropenia was found in 28 (77.8%) patients, autoimmune neutropenia in 6 (16.7%) patients, and congenital neutropenia in 2 (5.6%) patients. Neutrophil normalization was observed in 19 (52.8%) of the patients.

CONCLUSIONS

Chronic neutropenia is a heterogeneous picture that presents with different clinical symptoms in childhood. The cause of neutropoenia in children is usually benign and resolves spontaneously but especially in those with severe neutropoenia genetic examination should be performed.

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.

ABO, secretor, and Lewis carbohydrate histo-blood groups are associated with autoimmune neutropenia of early childhood in Danish patients

Background

Autoimmune neutropenia of early childhood (AIN) is caused by autoantibodies directed against antigens on the neutrophil membrane. The ABO, secretor, and Lewis histo‐blood group systems control the expression of carbohydrate antigens and have previously been linked to autoimmune diseases. We aimed to investigate the association between genotypes and the risk of AIN in Danish patients.

Study Design and Methods

One hundred fifty‐four antibody‐positive AIN patients were included. Controls (n = 400) were healthy unrelated Danish blood donors. Molecular determination of ABO, secretor (FUT2), and Lewis (FUT3) genotypes were determined using real‐time polymerase chain reaction (qPCR) or Sanger sequencing to infer the prevalence of Lewis antigens (Le^a and Le^b) and secretor (SeSe or Sese) or nonsecretor (sese) phenotypes.

Results

Blood type O was more common in controls (46.8%) than in AIN patients (36.4%) (OR = 0.65; p = 0.028). Secretors of H Le^b antigens were less frequent among AIN patients (25.2%) than controls (35.0%) (OR = 0.62; p = 0.037).

Discussion

ABO blood group antigens and the secretion of these antigens are associated with a diagnosis of AIN. The mechanism underlying the association between autoimmunity and interaction among ABO, secretor, and Lewis genotypes has not yet been elucidated, but several studies indicate a connection to the gut microbiota.

Diagnosis and management of neutropenia in children: The approach of the Study Group on Neutropenia and Marrow Failure Syndromes of the Pediatric Italian Hemato-Oncology Association (Associazione Italiana Emato-Oncologia Pediatrica - AIEOP)

Neutropenia refers to a group of diseases characterized by a reduction in neutrophil levels below the recommended age threshold. The present study aimed to review the diagnosis and management of neutropenia, including a diagnostic toolkit and candidate underlying genes. This study also aimed to review the progress toward the definition of autoimmune and idiopathic neutropenia rising in infancy or in late childhood but without remission, and provide suggestions for efficient diagnostics, including indications for the bone marrow and genetic testing. The management and treatment protocols for common and unique presentations are also reviewed, providing evidence tailored to a single patient.

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.

Phagocytosis of Mature Granulocytes by Bone Marrow Macrophages in an Elderly Man with Adult-Onset Primary Autoimmune Neutropenia

Adult-onset primary autoimmune neutropenia (AIN) is an extremely rare but sometimes life-threatening disease. Its pathophysiology is still to be clarified. We describe a case with adult-onset primary AIN with phagocytosis of mature granulocytes by macrophages in bone marrow. A 77-year-old male was referred to our hospital with severe neutropenia. Based on the normal cellular bone marrow without morphological dysplasia and the positivity of anti-neutrophil antibodies in the serum, adult-onset primary AIN was diagnosed. After five years from the initiation of granulocyte colony-stimulating-factor therapy, neutropenia had progressed. At that time, the second bone marrow examination revealed segmented neutrophils phagocytosed by macrophages. Continuous low dose prednisolone succeeded to increase the neutrophil count. An impressive morphological feature of AIN indicated the destruction of mature granulocytes in bone marrow by antibody-dependent cellular phagocytosis mediated by granulocyte-specific antibodies. More cases should be accumulated to elucidate the precise mechanism and establish the optimal therapy.

Chronic neutropenia: how best to assess severity and approach management?

INTRODUCTION

Neutropenia is a relatively common finding in medical practice and the medical approach requires a gradual and pertinent diagnostic procedure as well as adapted management.

AREAS COVERED

The area of chronic neutropenia remains fragmented between diverse diseases or situations. Here physicians involved in different aspects of chronic neutropenia gather both the data from medical literature till the end of May 2021 and their experience to offer a global approach for the diagnosis of chronic neutropenia as well as their medical care.

EXPERT OPINION

In most cases, the neutropenia is transient, frequently related to a viral infection, and not harmful. However, neutropenia can be chronic (i.e. >3 months) and related to a number of etiologies, some clinically benign, such as so-called 'ethnic' neutropenia. Autoimmune neutropenia is the common form in young children, whereas idiopathic/immune neutropenia is a frequent etiology in young females. Inherited neutropenia (or congenital neutropenia) is exceptional, with approximately 30 new cases per 10⁶ births and 30 known subtypes. Such patients have a high risk of invasive bacterial infections, and oral infections. Supportive therapy, which is primarily based on daily administration of an antibiotic prophylaxis and/or treatment with granulocyte-colony stimulating factor (G-CSF), contributes to avoiding recurrent infections.

Autoimmune neutropenia associated with influenza virus infection in childhood: a case report

BACKGROUND

Although neutropenia is relatively frequent in infants and children and is mostly a benign condition with a self-limited course, it can lead to life-threatening severe infections. Autoimmune neutropenia is a relatively uncommon hematological disorder characterized by the autoantibody-induced destruction of neutrophils. It is usually triggered by viral infections with very few documented cases after influenza virus.

CASE PRESENTATION

An 8-month-old male infant presented at the emergency room with a 5-days history of fever up to 39.7 °C, cough and runny nose. In the blood test performed, severe neutropenia was diagnosed (neutrophils 109/μL). A nasopharyngeal aspirate revealed a positive rapid test for Influenza A. Serum antineutrophil antibodies were determined with positive results. Neutropenia targeted panel showed no mutations. Despite maintenance of severe neutropenia for 9 months the course was uneventful without treatment.

CONCLUSIONS

When severe neutropenia is diagnosed and confirmed, it is essential to rule out some potential etiologies and underlying conditions, since the appropriate subsequent management will depend on it. Although autoimmune neutropenia triggered by viral infections has been widely reported, it has seldom been reported after influenza infection. The benign course of the disease allows a conservative management in most cases.

Late-onset and long-lasting autoimmune neutropenia: an analysis from the Italian Neutropenia Registry

Primary autoimmune neutropenia (pAN) is typified by onset in early infancy and a mild/moderate phenotype that resolves within 3 years of diagnosis. In contrast, secondary AN is classically an adult disease associated with malignancy, autoimmunity, immunodeficiency, viral infection, or drugs. This study describes a cohort of 79 children from the Italian Registry who, although resembling pAN, did not fully match the criteria for pAN because neutropenia either appeared after age 5 years (LO-Np) or lasted longer than 3 years (LL-Np). These 2 categories compared with classical pAN showed a far inferior rate of resolution (P < .001), lower severity of neutropenia (P = .03), leukopenia (P < .001), lymphopenia (P < .001) with low B+ (P = .001), increased need of granulocyte colony-stimulating factor (P = .04), and increased frequency of autoimmunity over the disease course (P < .001). A paired comparison between LO-Np and LL-Np suggested that LO-Np had a lower rate of resolution (P < .001) and lower white blood cell (P < .001) and lymphocyte (P < .001) values, higher occurrence of apthae (P = .008), and a stronger association with autoimmune diseases/markers (P = .001) than LL-Np, thus suggesting a more pronounced autoimmune signature for LO-Np. A next-generation sequencing panel applied in a small subgroup of LO-Np and LL-Np patients identified variants related to immune dysregulations. Overall, these findings indicate that there are important differences among pAN LL-Np and LO-Np. Forms rising after 3 years of age, with low tendency to resolution, require tight monitoring and extensive immune investigations aimed to early identify underlying immunologic disease.

Association between human leukocyte antigens (HLAs) and human neutrophil antigens (HNAs) and autoimmune neutropenia of infancy in Danish patients

BACKGROUND

Autoimmune neutropenia of infancy (AIN) is a frequent cause of neutropenia in children. The disease is caused by antibodies against epitopes on the immunoglobulin G (IgG) Fc receptor type 3b (FcγIIIb). We investigated the possible association of human neutrophil antigens (HNA), human leukocyte antigen (HLA)-DR, and HLA-DQ alleles with AIN and the association of these genotypes with the presence of autoantibodies.

METHODS

Eighty AIN cases with a median age of 13.5 months were included. Controls were healthy unrelated Danish blood donors. Anti-HNA-1a autoantibodies were detected using a flow cytometric granulocyte immunofluorescence test (Flow-GIFT) with phenotyped donor cells for detection of antibody specificity. Molecular determination of HNA genotypes was determined using real-time polymerase chain reaction (q-PCR). High-resolution HLA-DRB1 and HLA-DQB1 were determined by next-generation sequencing.

RESULTS

Antibodies against HNA-1a were detected in 51% (n = 41) of AIN patients, and anti-HNA-1b was detected in 3% (n = 2) of cases. In 46% of cases, the antibodies were anti-FcγIIIb-reactive. FCGR3B*01+,*02-,*03- was more common (odds ratio, 6.70; P < .0001), and FCGR3B*01-,*02+,*03- was less common (odds ratio, 0.30; P < .0001) among AIN cases. HNA-1a antibodies were significantly more frequent among AIN cases with the FCGR3B*01+,*02-,*03- genotype (odds ratio, 3.86; P < .007). The HLA-DRB1*14 - HLA-DQB1*05:03 haplotype was significantly more common (odds ratio, 7.44; P < .0001) in AIN patients.

CONCLUSION

The HLA haplotype HLA-DRB1*14 - DQB1*05:03 is associated with Danish AIN cases. Among Danish AIN patients, anti-HNA-1a is the most common autoantibody, and the antibody is more common in cases with the FCGR3B*01+,*02-,*03- genotype.

Autoimmune pancytopenia after liver transplantation: A case report

INTRODUCTION

Autoimmune hemolytic anemia (AIHA), immune thrombocytopenia (ITP), and autoimmune neutropenia (AIN) are reported in the literature after liver, intestinal, heart, pancreas, and kidney transplants. We report a case of autoimmune pancytopenia (AIHA, AIN and ITP) 9 years after liver transplantation with confirmed erythrocyte and neutrophil auto-antibodies.

CASE REPORT

A 49 years old man was admitted to our hospital presented with dysentery and fever, with history of liver transplantation in 2008. Laboratory evaluation demonstrated hemoglobin: 7.2 g/dL, granulocytes: 0.10 × 10⁹/L and platelets: 15 × 10⁹/mm³; indirect bilirubin: 3.62 mg/dL; lactate dehydrogenase: 603 U/L. Direct antiglobulin test revealed a monospecific anti-IgG plus C3 and the acid eluate was reactive to all panel red cells, consistent with an AIHA. Granulocyte immunofluorescence test (GIFT) and agglutination test (GAT) were reactive for granulocytes. Test with Luminex technology for human neutrophil antigen (HNA) antibody detection was strong reactive with beads expressing HNA-1a, -1b, -1c, -2, -4a and -5a antigens. HNA genotyping revealed the presence of the corresponding antigens, confirming the autoantibodies. Test with Luminex technology for human leucocyte antigen (HLA) antibody detection was negative. Monoclonal antibody immobilization of platelet antigens (MAIPA) assay was negative. Viral causes were excluded. The condition was compatible with clinical onset of autoimmune pancytopenia. Prednisone was administered at an initial dose of 1 mg/kg/day and immunosuppressive therapy was adjusted. This treatment resulted in rapid resolution of pancytopenia.

CONCLUSION

Combined autoimmune pancytopenia (AIHA, AIN and ITP) is a rare condition that may occur after liver transplantation. Early recognition of this phenomenon permits appropriate treatment.

The blood protein hCAP-18 in neutropenia: An 18-month experience of a new ELISA for clinical use

Neutropenia as an isolated clinical finding may include aetiologies ranging from severe disease to a transient condition, and differential diagnosis may be challenging. Previous data and clinical experience suggest that low levels of the neutrophil-derived protein human 18 kDa cathelicidin antimicrobial protein (hCAP-18) in the blood are predictive of more severe forms of neutropenia. The objective of this study was to present the results from a newly developed ELISA method that has been used in clinical routine in Sweden since 2018 for quantification of hCAP-18 in blood plasma. Using this method, we report that patients with severe disease analysed during the study period presented with low or undetectable levels of blood plasma hCAP-18, validating its use as screening tool for severe neutropenia. Furthermore, neutropenic patients as a group displayed lower levels of hCAP-18 as compared to blood donors. Within the group of neutropenic patients, those with neutrophil antibodies displayed significantly higher hCAP-18 levels compared to patients with idiopathic neutropenia. By including an analysis of hCAP-18 in the primary investigation of neutropenia, an increased accuracy in differential diagnosis is achieved, thus contributing to reduced costs of neutropenia management.

Infant Pyogenic Liver Abscess Complicated With Autoimmune Neutropenia: Two Cases

Approximately 90% of patients with autoimmune neutropenia (AIN) suffer from mild infections although neutrophil count often decreases to <500/μL. Here, we report 2 cases of infant pyogenic liver abscess complicated with AIN. We should consider the possibility of AIN as an underlying disease when diagnosing pyogenic liver abscess during childhood.

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.

Outcomes of Isolated Neutropenia Referred to Pediatric Hematology-Oncology Clinic

BACKGROUND

Children with isolated neutropenia (absolute neutrophil count [ANC] <1500/μL) are frequently referred to pediatric hematology and oncology clinics for further diagnostic evaluation. Scant literature exists on interventions and outcomes for isolated neutropenia. We hypothesized that children will have resolution of their neutropenia without the need for intervention(s) by a pediatric hematologist and oncologist.

METHODS

We performed a 5.5-year institutional review board-approved retrospective chart review of children referred to our pediatric hematology and oncology clinics for isolated neutropenia. Neutropenia was categorized as mild (ANC of 1001-1500/μL), moderate (ANC of 500-1000 μL), severe (ANC of 201-500/μL), or very severe (ANC of ≤200/μL).

RESULTS

Among 155 children referred with isolated neutropenia, 45 (29%) had mild neutropenia, 65 (42%) had moderate neutropenia, 30 (19%) had severe neutropenia, and 15 (10%) had very severe neutropenia. Only 29 (19%) children changed to an ANC category lower than their initial referral category. At a median follow-up of 12 months, 101 children had resolution of neutropenia, 40 children had mild neutropenia, 10 children had moderate neutropenia, 3 children had severe neutropenia, and 1 patient had very severe neutropenia. A specific diagnosis was not identified in most (54%) children. The most common etiologies were viral suppression (16%), autoimmune neutropenia (14%), and drug-induced neutropenia (8%). Black children had a 3.5 higher odds of having persistent mild neutropenia. Six (4%) children received granulocyte colony-stimulating factor therapy.

CONCLUSIONS

Most children referred for isolated neutropenia do not progress in severity and do not require subspecialty interventions or hospitalizations.

Human neutrophil antigens: Nature, clinical significance and detection

Granulocytes are an essential part of both the innate and adaptive immune systems. Human neutrophil antigens (HNAs) are a family of epitopes that are located on glycoproteins that are mostly expressed on human granulocytes. Antibodies that recognize these epitopes have been associated with neutropenia, transfusion complications, haematopoietic stem cell transplant nonengraftment and renal transplant rejection. Currently, there are fourteen recognized HNA alleles across five antigen systems (HNA-1 through HNA-5), the molecular basis of which are located on the genes FCGR3B, CD177, SLC44A2, ITGAM and ITGAL, respectively. Elucidation of the associated genes has permitted the development of testing strategies for HNA typing and aided understanding of the associated epitopes. This review will outline the associated clinical conditions that require HNA investigation and how these are performed in specialized laboratories. Investigations provided are both reactive for patients with a variety of existing or suspected neutropenias and proactive in the testing of blood component donors in order to reduce the potential risk to patients who require transfusion.

Congenital Cytomegalovirus and Autoimmune Neutropenia: Cause or Coincidence?

BACKGROUND

Congenital cytomegalovirus (CCMV) accounts for high rates of infant morbidity and mortality. Neutropenia is a common finding in CCMV infection, of which the age of presentation overlaps with autoimmune neutropenia (AIN). AIN represents one of the most common forms of chronic neutropenia in childhood.

METHODS

A literature search exploring biologic associations between CCMV and AIN was conducted: PubMed (MEDLINE), Ovid and Web of Science. We further describe 2 cases of concurrent CCMV and AIN. Both cases were confirmed with the indirect granulocyte immunofluorescence test and alternative etiologies for neutropenia excluded.

RESULTS

Our 2 patients represent confirmed cases of AIN in infants with CCMV. One patient demonstrated neutropenia while undergoing treatment with Valganciclovir, while the other was never treated. With interruption of Valganciclovir in infant A, neutrophil counts (ANC) did not improve and upon resumption of treatment ANC remained static.

CONCLUSIONS

Further studies examining a possible biologic link between CCMV and AIN are advocated for. We encourage clinicians to actively consider AIN in the differential diagnosis of all infants with CCMV presenting with neutropenia.

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.

The Role of Anti-Neutrophil Antibodies in the Etiologic Classification of Childhood Neutropenia: A Cross-Sectional Study in a Tertiary Center

Infections, drugs, malignancies, immunodeficiency, and autoimmunity may cause neutropenia. In primary autoimmune neutropenia, anti-neutrophil antibodies (ANeuA) bind to membrane antigens of neutrophils, which give rise to peripheral destruction of neutrophils. However, it is not always easy to detect these antibodies. This study aims to investigate the etiology of neutropenia, and at the same time to evaluate the immune mechanisms by ANeuA testing using granulocyte indirect immunofluorescence test. In our study, 310 neutropenic patients who were between 3 months and 18 years of age were evaluated. ANeuA screening tests were performed in 108 neutropenic patients (group 1), and these patients were divided into 2 subgroups as persistent neutropenia (group 1P, n=12) and recovered neutropenia (group 1R, n=96). Besides, a control group in the same age range was formed, consisting of 39 non-neutropenic children (group 2). ANeuA serum levels were also checked in these groups, and no statistically significant difference could be found between groups 1 and 2, or between groups 1P and 1R, regarding ANeuA levels. As a conclusion, our study was the first comprehensive research in Turkey investigating the large-scale etiology of neutropenia. Moreover, while ANeuA screening tests did not provide sufficient insight for immune neutropenia, we argue that it is not necessary for routine use and that further research in the etiology of neutropenia is required.

Paediatric autoimmune neutropaenia

Neutropaenia is defined as an absolute neutrophil count (ANC) of less than 1500 cells/µL and is often divided into mild (ANC: 1000 to 1500 cells/µL), moderate (ANC: 500 to 1000 cells/µL) and severe (ANC: >500 cells/µL) neutropaenia. Autoimmune neutropaenia is arguably one of the most clinically relevant forms of neutropaenia and is defined by an ANC of <500 cells/µL alongside the confirmed presence of anti-neutrophil antibodies. It is a rare subset of neutropaenia boasting an incidence of just 1 in 100 000 infants and is thought to be caused as a result of a 'surveillance escape event' of the immune system. This case report identifies key issues in the diagnosis and monitoring of paediatric patients with recurrent neutropaenia and reviews current literature relating to its management in hospital and community settings.

Efficacy of using trimethoprim-sulfamethoxazole prophylaxis in an adult patient with autoimmune neutropenia

A 63-year-old man was admitted for pneumonia with neutropenia. After the pneumonia resolved with administration of antibiotics and granulocyte colony-stimulating factor, he was diagnosed with autoimmune neutropenia (AIN) on the basis of bone marrow findings and positive antineutrophil antibodies. He had recurring high fever once or twice a month with productive cough and an elevated serum C-reactive protein level. However, after the initiation of treatment with oral trimethoprim-sulfamethoxazole (TMP/SMX), the respiratory tract infection no longer recurred. The standard management for adults with AIN has not been established. In our case, the recurrent infection was resolved with TMP/SMX prophylaxis. Thus, TMP/SMX prophylaxis may be beneficial for managing adults with AIN.

Medicinal Uses of Hematopoietic Growth Factors in Neonatal Medicine

This review focuses on certain hematopoietic growth factors that are used as medications in clinical neonatology. It is important to note at the chapter onset that although all of the pharmacological agents mentioned in this review have been approved by the US Food and Drug administration for use in humans, none have been granted a specific FDA indication for neonates. Thus, in a sense, all of the agents mentioned in this chapter could be considered experimental, when used in neonates. However, a great many of the pharmacological agents utilized routinely in neonatology practice do not have a specific FDA indication for this population of patients. Consequently, many of the agents reviewed in this chapter are considered by some practitioners to be nonexperimental and are used when they judge such use to be "best practice" for the disorders under treatment.The medicinal uses of the agents in this chapter vary considerably, between geographic locations, and sometimes even within an institutions. "Consistent approaches" aimed at using these agents in uniform ways in the practice of neonatology are encouraged. Indeed some healthcare systems, and some individual NICUs, have developed written guidelines for using these agents within the practice group. Some such guidelines are provided in this review. It should be noted that these guidelines, or "consistent approaches," must be viewed as dynamic and changing, requiring adjustment and refinement as additional evidence accrues.

Genotyping of human neutrophil antigens 1, 3, 4 and 5 using a novel multiplex polymerase chain reaction

OBJECTIVES

Our study aimed to establish a novel multiplex polymerase chain reaction (PCR) for rapid simultaneous detection of all relevant human neutrophil antigen (HNA)-1, -3, -4 and -5 alleles.

BACKGROUND

Granulocyte-reactive antibodies are involved in several diseases, such as neonatal alloimmune neutropenia, autoimmune neutropenia and transfusion-related acute lung injury. A panel of well-defined test granulocytes is required for diagnostic antibody detection and prospective blood donor screening. Several genotyping methods for the detection of HNA alleles have been described, but most approaches require separate amplification of each HNA allele or at least a separate amplification of the HNA-1 alleles.

METHODS

The new method is based on simultaneous detection in one reaction tube, where each HNA-1 allele is amplified by two allele-specific primers, one primer of which is labelled with a fluorescent dye (HEX, FAM). Allelic polymorphisms for HNA-3, -4 and -5 were amplified with one common unlabelled primer and two fluorescence-labelled (HEX, FAM) allele-specific primers. DNA fragments of HNA alleles are analysed on a Genetic Analyser 3130xl by amplicon size and fluorescent dye. A total of 110 blood donors with known genotypes were studied.

RESULTS

In the 110 DNA samples studied, all HNA-1, -3, -4 and -5 alleles could be detected precisely. All results matched perfectly with those from reference typing by PCR-sequence-specific primer. Amplification performed well even at low DNA concentrations (10 ng μL^-1 ).

CONCLUSION

Our method enables fast and easy genotyping of all relevant HNA-alleles in one PCR reaction. Results are easy to analyse due to different amplicon sizes and fluorescent dyes. Furthermore, the method is suitable for high sample throughput.

Severe Transitory Neonatal Neutropenia Associated with Maternal Autoimmune or Idiopathic Neutropenia

PURPOSE

Neonatal immune neutropenia is observed in rare cases in newborns from mothers with idiopathic or autoimmune neutropenia, secondary to passive transfer of maternal granulocyte auto-antibodies.

METHODS

We performed a literature review and report four supplementary cases from the French registry of neutropenia.

RESULTS

Only 14 cases (11 mothers, 14 newborns) have been reported. Granulocyte aggregation (GAT) and granulocyte indirect immunofluorescence test (GIFT) are the recommended laboratory procedures for antibody detection. Monoclonal antibody-specific immobilization of granulocyte antigens (MAIGA)-confirmed antibody specificity. Antibody detection in newborns is not generally possible owing to extreme neutropenia. In half of the cases autoantibodies against neutrophils (AAN) were positive in maternal sera (7 out of 11). In some newborns tested, IgG⁺ AAN were also positive, with disappearance in parallel of spontaneous neutrophil count improvement. No correlation between maternal type of AAN and titer and neonatal neutropenia can be established. Neutropenia resolved spontaneously between 2 weeks and 4 months. Infections in newborns were observed in 43% of cases, with no deaths reported. Granulocyte colony-stimulating factor (G-CSF) was administered to some newborns (5 out of 14) in the case of infections. Low-dose G-CSF administered to childbearing women during pregnancy could be proposed to prevent neutropenia in newborns.

CONCLUSIONS

From the few cases reported so far it is impossible to draw any conclusions regarding frequency, risk factors, and outcome, but the overall prognosis for newborns seems good. Because it can be associated with potentially severe neonatal infections, autoimmune neutropenia in childbearing mothers should be closely monitored in collaboration with gynecologists and pediatricians.

Reduction of CFU-GM and circulating hematopoietic progenitors in a subgroup of children with chronic neutropenia associated with severe infections and delayed recovery

Myelopoiesis was evaluated in 66 pediatric patients with chronic neutropenia who were positive for anti-neutrophil antibodies (median age at diagnosis: 11 months, median neutrophil count at diagnosis: 419/μl). Other causes of neutropenia were excluded. Bone marrow morphology, clonogenic tests and/or the peripheral blood CD 34+ cell count, and apoptotic rate were evaluated in 61 patients with neutropenia lasting > 12 months or severe infections. The peripheral blood CD 34+ cell count and apoptotic rate were evaluated in five patients with shorter neutropenia. The median follow-up time was 29 months (range 7-180 months). Forty-seven patients (71.2%) had a spontaneous recovery after 7-180 months (median 29 months). The group of patients younger than 24 months at diagnosis (n = 50) had a higher probability of recovery (40/50 vs. 7/16 χ2 p<0.01) with a shorter period of neutropenia (median 26 versus 47 months, Kaplan-Meier analysis p = 0.001). The colony-forming units-granulocyte-macrophage (CFU-GM) were significantly decreased in 26/35 patients (74%) evaluated for clonogenic tests. All patients with normal CFU-GM recovered (9/9 patients); whereas, neutropenia persisted in 12/26 patients with reduced CFU-GM (46%, Pearson χ2 p = 0.02). In 36/55 (65%) patients evaluated by flow cytometry we observed reduced circulating CD34+ cells compared with controls of the same age. An increase in the circulating CD34+ cell apoptotic rate was observed in 28/55 patients (51%). Infections requiring hospitalization were observed in 9/18 (50%; Pearson χ2, p = 0.03) patients with both decreased circulating CD34+ cells and increased CD34+ apoptotic rates. In the group aged < 24 months, we observed a significant correlation between the persistence of neutropenia and decreased circulating CD34+ cells (Pearson χ2 p = 0.008). In conclusion, reduced CFU-GM and circulating hematopoietic progenitors were observed in a subgroup of children with chronic neutropenia who were positive for anti-neutrophil antibodies and had a higher incidence of severe infections and delayed spontaneous remission.

Chronic Neutropenia in Children With Abscess Forming Cervical Lymphadenitis Caused by Staphylococcus aureus

BACKGROUND

Suppurative cervical lymphadenitis is rare in children with limited information about the frequency of neutropenia in any series.

METHODS

We conducted a retrospective review of pediatric patients in whom suppurative cervical lymphadenitis was diagnosed between April 2011 and March 2016 at a tertiary children's hospital in Tokyo, Japan. Microbiologically confirmed cases of cervical lymphadenitis with abscess formation were included in the analysis.

RESULTS

Twenty-five patients (median age, 1 yr old; 64% female) with abscess formation caused by Staphylococcus aureus were identified. Among these 25 patients, 5 (20%) met the criteria for chronic neutropenia and 4 (80%) received the final diagnosis of autoimmune neutropenia based on the identification of the serum anti-CD16 antibodies.

CONCLUSIONS

Chronic neutropenia and autoimmune neutropenia were relatively common among infants with suppurative cervical lymphadenitis caused by S. aureus.

Idiopathic neutropenia of infancy: Data from the Italian Neutropenia Registry

Autoimmune neutropenia of infancy (AIN) is characterized by low risk of severe infection, tendency to spontaneously resolve and typically onset at ≤4-5 years of age; it is due to auto-antibodies whose detection is often difficult. In case of negativity of 4 antineutrophils autoantibody tests, after having excluded ethnic, postinfection, drug induced, or congenital neutropenia, according to the Italian guidelines the patients will be defined as affected by "idiopathic neutropenia" (IN). We describe the characteristics of 85 IN patients enrolled in the Italian neutropenia registry: they were compared with 336 children affected by AIN. The 2 groups were clinically very similar and the main differences were detection age (later in IN), length of disease (longer in IN) and, among recovered patients, age of spontaneous recovery: the median age at resolution was 2.13 years in AINs and 3.03 years in INs (P = .00002). At bivariate analysis among AIN patients earlier detection age (P = .00013), male sex (P = .000748), absence of leucopenia (P = .0045), and absence of monocytosis (P = .0419) were significantly associated with earlier recovery; in the IN group only detection age (P = .013) and absence of monocytosis (P = .0333) were significant. At multivariate analysis detection age and absence of monocytosis were independently significant (P = 6.7e-05 and 4.4e-03, respectively) in the AIN group, whereas in the IN group only detection age stayed significant (P = .013).