Diagnosis and management of chronic neutropenia during childhood

Incidence of Severe Chronic Neutropenia in South Korea and Related Clinical Manifestations: A National Health Insurance Database Study

Background and objectives: Severe chronic neutropenia (SCN) is a condition in which absolute neutrophil counts remain at a low level (under 500/µL) over months or years. Because of the rare onset of SCN, its epidemiology, prognosis, and clinical manifestations have not yet been fully understood. In particular, large-cohort studies in Asian countries are still insufficient. Therefore, in this study, national health insurance data was used to investigate the epidemiologic features and prognosis of SCN in South Korea. Materials and Methods: The data from the Health Insurance Review and Assessment database recorded between 1 January 2011 and 31 December 2015 were explored. SCN was defined based on the ICD-10 code, registry of benefit extension policy, and inclusion criteria of the study. After identifying patients with SCN, annual incidence and their co-morbidities were analyzed. Results: Among the initially identified patients with severe neutropenia (N = 2145), a total of 367 patients had SCN and were enrolled. The annual incidence rate of SCN ranged from 0.12 to 0.17 per 100,000 person-year (PY) during the study period. The highest incidence was observed in pediatric patients aged between 0 to 9 years (N = 156), followed by women in their fifties (N = 43). The total incidence rate was 0.17 in females and 0.12 in males (Relative risk (RR): 1.43, 95%, CI: 1.16–1.76). The most common accompanying condition was mild respiratory infection, but about 3.2% of patients progressed to hematologic malignancy after an average of 2.4 years. Conclusions: This nationwide population-based epidemiological study showed that incidence of SCN is higher in pediatrics and middle-aged women. As progression to hematologic malignancy was significantly higher in the age of in 45–49 years old, careful follow-up is necessary in this group. However, since this study lacks the molecular information, these finding need to be interpreted with great caution.

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.

Etiology, clinical outcome, and laboratory features in children with neutropenia: analysis of 104 cases

BACKGROUND

Neutropenia is not uncommon in childhood. The aim of our study was to analyze the underlying causes of neutropenia and to evaluate its clinical significance in a series of children referred to our center.

METHODS

One hundred and four consecutive children with neutropenia were enrolled in this study. Clinical and laboratory features were analyzed.

RESULTS

The majority of patients (63.5%) showed chronic neutropenia. Among all chronic forms, the most frequent was chronic idiopathic neutropenia (CIN), followed by autoimmune neutropenia (AIN). Congenital neutropenia was identified in 6 patients. Acute neutropenia was mainly due to infections. Overall, at the time of first detection, neutropenia was more frequently severe or moderate. One-third of our patients who presented with severe neutropenia were ultimately diagnosed with a post-infectious acute form. Conversely, nearly half patients with CIN, AIN, or congenital neutropenia showed moderate/mild neutropenia at onset. Among patients with AIN and CIN, nearly half recovered between 7 months and 46 months and approximately one-fourth experienced infectious episodes during follow-up. No significant difference was noticed in terms of mean ANC between patients with and without remission, neither between patients with and without infections.

CONCLUSIONS

Our study confirms the great etiological heterogeneity of neutropenia in children. We could not demonstrate a correlation between ANC level at onset and the underlying disorder, nor a correlation between mean ANC and duration of neutropenia or infectious episodes during follow-up. Neutropenia remains a disease of concern to pediatricians, requiring several laboratory investigations, prolonged follow-up, and, in few cases, advanced molecular methods.

An infant with chronic severe neutropenia

Neutropenia in infancy and childhood poses a diagnostic challenge as the aetiology ranges from acute life-threatening conditions to chronic benign diseases. Chronic benign neutropenia of infancy is a rare disorder occurring in 1:100,000. The neutrophil count continues to be low for a prolonged period until spontaneous resolution by the age of 3-4 years. Such infants are having higher incidences of minor infections requiring treatment with antibiotics and rare incidences of meningitis and sepsis. The authors describe an infant presenting with fever and cervical lymphadenitis, who was found to have isolated severe neutropenia and its persistence posing a diagnostic challenge. The prolonged course with minor infections and absence of serious underlying conditions finally confirmed chronic benign neutropenia of infancy.

Neutrophils in innate host defense against Staphylococcus aureus infections

Staphylococcus aureus has been an important human pathogen throughout history and is currently a leading cause of bacterial infections worldwide. S. aureus has the unique ability to cause a continuum of diseases, ranging from minor skin infections to fatal necrotizing pneumonia. Moreover, the emergence of highly virulent, drug-resistant strains such as methicillin-resistant S. aureus in both healthcare and community settings is a major therapeutic concern. Neutrophils are the most prominent cellular component of the innate immune system and provide an essential primary defense against bacterial pathogens such as S. aureus. Neutrophils are rapidly recruited to sites of infection where they bind and ingest invading S. aureus, and this process triggers potent oxidative and non-oxidative antimicrobial killing mechanisms that serve to limit pathogen survival and dissemination. S. aureus has evolved numerous mechanisms to evade host defense strategies employed by neutrophils, including the ability to modulate normal neutrophil turnover, a process critical to the resolution of acute inflammation. Here we provide an overview of the role of neutrophils in host defense against bacterial pathogens and discuss strategies employed by S. aureus to circumvent neutrophil function.

Diagnosis of autoimmune neutropenia by neutrophil-bound IgG and IgM antibodies

Autoimmune neutropenia (AIN) in infancy is caused by antineutrophil (granulocyte-specific) autoantibodies. These antibodies are rarely found in circulation because their serum levels are extremely low. We hypothesized that a direct granulocyte immunofluorescence test (D-GIFT) that enables us to detect neutrophil-bound autoantibodies consisting of both immunoglobulin (Ig) G and IgM has better diagnostic value than the detection of circulating autoantibodies. Whole blood (100 μL) was obtained from 50 infants with AIN, 12 infants with transient neutropenia, and 37 control infants. D-GIFT was performed using both fluorescein isothiocyanate-conjugated antihuman IgG Fc portion monoclonal antibodies and fluorescein isothiocyanate antihuman IgM monoclonal antibodies. Results were assessed as relative fluorescence intensity (RFI). The RFIs of antineutrophil IgG-bound and antineutrophil IgM-bound cells in patients with AIN were significantly higher than those in patients with transient neutropenia and in controls. Positive results, as assessed by RFI scores of more than 1.81 in either antineutrophil IgG-bound or antineutrophil IgM-bound cells, showed the sensitivity and specificity of D-GIFT, and the areas under the receiver operating characteristic curve (0.98, 0.98, and 0.997, respectively) in the diagnosis of AIN. D-GIFT detecting both neutrophil-bound IgG autoantibodies and IgM autoantibodies has discriminatory power for identifying patients with AIN and, therefore, can be a useful diagnostic test.

A case of systemic amyloidosis associated with cyclic neutropenia

Reactive AA amyloidosis is caused by the accumulation of the acute phase reactant, serum amyloid A (SAA), as a complication of chronic inflammatory conditions. Cyclic neutropenia is a rare hereditary disorder characterized by repeated episodes of neutropenia at regular intervals, with or without concurrent infection, and is known to be a rare cause of AA amyloidosis. Here, we report a case of a patient who developed systemic AA amyloidosis following a prolonged course of undiagnosed cyclic neutropenia. The patient had a history of recurrent infections since infancy and developed goiter, proteinuria, and azotemia at age 14 years. Her SAA level was markedly increased (601.8 μg/mL, normal range <8 μg/mL), and a thyroid and kidney biopsy revealed typical lesions of AA amyloidosis. Amyloid deposits were also detected in the myocardium, colon, and gallbladder. She had repeated episodes of neutropenia regularly at 3-week intervals and a pathogenic mutation in the ELA2 gene. After 10 months of treatment with recombinant human granulocyte colony-stimulating factor, her SAA level normalized (<2.5 μg/mL), but her renal function did not recover. This case clearly shows that cyclic neutropenia can be complicated by AA amyloidosis unless it is detected early and treated adequately.

Autoimmune neutropenia due to antineutrophil antibodies in a patient with primary sclerosing cholangitis

Autoimmune neutropenia (AIN) is defined as a decrease in the circulating absolute neutrophil count (ANC) to less than 1500/μl caused by serum antineutrophil antibodies. Secondary AIN is associated with various autoimmune diseases. Herein we present the case of a patient with primary sclerosing cholangitis (PSC) who developed secondary AIN. A 19-year-old man was admitted due to liver injury, and a diagnosis of PSC was established by cholangiogram and liver biopsy. Severe neutropenia, with the ANC down to 130/μl, developed during his hospital course. No medications had been given at that time and bone marrow aspiration revealed no abnormality. Therefore we suspected secondary AIN as a causative etiology and examined whether antineutrophil antibodies were detectable in the patient's sera by flow cytometric analysis of the granulocyte indirect immunofluorescence test. We found that antineutrophil antibody was strongly positive on admission, and the titer decreased along with recovery from neutropenia. This is the first reported case of a patient with PSC who developed AIN, with detection of serum antineutrophil antibodies.

Prolonged acquired neutropenia in children

BACKGROUND

Acquired neutropenia is not uncommon in childhood. This study investigated the risk factors associated with developing prolonged acquired neutropenia.

PROCEDURE

We reviewed 66,062 hospital admission medical records from the 5-year period January 1, 2002 to December 31, 2006 to identify neutropenic patients, with and without follow-up of their neutropenic course until December 31, 2007. After excluding patients with malignancy, collagen disease, bone marrow failure, prematurity, hereditary disease, congenital neutropenia, immunodeficiency, or status post-liver transplantation, 735 admissions with acquired neutropenia were included in our study.

RESULTS

A total of 474 patients with 735 admissions had moderate or severe neutropenia during the 5-year period. Among the 252 acquired neutropenia patients who had follow-up for at least 1 month, 226 patients recovered within 3 months, while 26 patients remained neutropenic after 3 months. Of these 26 patients, 14 recovered after 1 year. An absolute neutrophil count of <500/mm(3) (odds ratio [OR]: 13.66, 95% confidence interval [CI]: 2.90-64.41), thrombocytosis (OR: 5.76, 95% CI: 1.78-18.58), and age <1 year (OR: 4.93, 95% CI: 1.03-23.54) were associated with prolonged acquired neutropenia, as shown by multivariate logistic regression. Kaplan-Meier analysis showed that neutropenia associated with cytomegalovirus (CMV) was more prolonged than neutropenia associated with influenza or Epstein-Barr virus infection.

CONCLUSIONS

Prolonged acquired neutropenia was associated with younger age, thrombocytosis, and CMV infection. Neutropenic infants with CMV infection may require antiviral therapy to prevent prolonged acquired neutropenia.

Idiopathic neutropenia of childhood is associated with Fas/FasL expression

Idiopathic neutropenia (IN) in children is characterized by decreased neutrophil counts (<1500/microl), can be acute or chronic (greater than 6 months duration). The pathophysiology is not well understood; therefore, potential mechanisms of pediatric IN were investigated. An increase in Fas transcripts in neutrophils of IN patients compared to age-matched healthy control (HC) neutrophils was observed (p<0.005). Increased expression of Fas protein was found in IN neutrophils, while Fas surface expression on other immune cells was similar. Plasma from acute IN patients had higher protein levels of soluble FasL than chronic IN patients. When HC neutrophils were incubated in plasma from IN patients, greater rates of apoptosis were observed. Biochemical studies suggest the apoptotic factor(s) in plasma is heat-sensitive, non-IgG, and 12-50 kD protein. Addition of anti-sFasL blocking antibodies to patient plasma caused a statistically significant decrease in neutrophil apoptosis. These studies show that the Fas/FasL pathway could be associated with neutrophil apoptosis in childhood IN.

Primary Immunodeficiencies

Primary immunodeficiencies (PIDs), once considered to be very rare, are now increasingly recognized because of growing knowledge in the immunological field and the availability of more sophisticated diagnostic techniques and therapeutic modalities [161]. However in a database of >120,000 inpatients of a general hospital for conditions suggestive of ID 59 patients were tested, and an undiagnosed PID was found in 17 (29%) of the subjects tested [107]. The publication of the first case of agammaglobulinemia by Bruton in 1952 [60] demonstrated that the PID diagnosis is first done in the laboratory. However, PIDs require specialized immunological centers for diagnosis and management [33]. A large body of epidemiological evidence supports the hypothesis of the existence of a close etiopathogenetic relation between PID and atopy [73]. In particular, an elevated frequency of asthma, food allergy (FA), atopic dermatitis and enteric pathologies can be found in various PIDs. In addition we will discuss another subject that is certainly of interest: the pseudo-immunodepressed child with recurrent respiratory infections (RRIs), an event that often requires medical intervention and that very often leads to the suspicion that it involves antibody deficiencies [149].

Benign chronic neutropenia with abnormalities involving 16q22, affecting mother and daughter

We report a case of familial, chronic, benign neutropenia in a 17-year-old female showing (1) the spontaneous expression of a heritable rare fragile site at 16q22 and (2) a deletion at the same region. The del(16)(q22), which most likely originated from the fragile site, was the main clonal abnormality detected in the patient's bone marrow cells, whereas a few cells with either del(16)(q22) or fra(16)(q22) were seen in the patient's peripheral blood. Interestingly, the del(16q) was also detected in the patient's uncultured cells, as demonstrated by FISH, excluding an in vitro origin of the del(16q) during culture. The bone marrow was hypocellular with decreased neutrophils and their precursors. Absolute neutrophil counts ranged from (0.62 to 1.24) x 10(9)/L with a median value of 1.02 x 10(9)/L. The patient had a more severe neutropenia than her mother, which correlated with the presence of more cells with del(16q) in the marrow. The patient's mother, who was also diagnosed with neutropenia, revealed only a few cells with the rare fra(16)(q22) in her peripheral blood cells, whereas her bone marrow showed cells with both fra(16)(q22) and del(16)(q22), although the del(16q) was present in only 2/20 cells. Some possible candidate genes contributing to the pathogenesis of the neutropenia are discussed. Chromosome abnormalities involving the 16q22 breakpoint have been observed in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). In this patient, the del(16)(q22) risk factor is unknown for subsequent development of MDS or AML. Another point to consider is the need to determine the origin of a chromosome abnormality, particularly when the clinical picture does not fit the chromosome findings. Although, the observation of a constitutional structural abnormality in a mosaic form is an extremely rare event, it is somewhat different in the case of a fragile site expression, which can, as in this case, be present in some cells and not in others.

Immune suppression and considerations for dental care

Immunocompromised individuals present a challenge to oral health care providers. As the spectrum of patients with dysfunctional immune responses continues to broaden, practitioners should be able to identify these patients, understand the potential for complications, and manage their dental care safely and effectively. This article reviews various immune deficiencies, addresses complications that may result from an individual's immune status, and discusses dental considerations for these patients.

Efficacy of prophylactic use of trimethoprim-sulfamethoxazole in autoimmune neutropenia in infancy

PURPOSE

Most children with autoimmune neutropenia (AIN) have a benign clinical course because of the spontaneous resolution of neutropenia. The authors observed the clinical course of AIN in infancy accompanied by the prophylactic use of trimethoprim-sulfamethoxazole (TMP-SMX) during neutropenia.

PATIENTS AND METHODS

Eight infants with AIN were followed by serial tests for antineutrophil antibodies and management of infectious complications.

RESULTS

The spontaneous disappearance of antineutrophil antibodies that preceded the normalization of the neutrophil count was found in all patients. Until the resolution of neutropenia, TMP-SMX was administered in five patients, resulting in a reduction in the incidence of infection with no adverse effects.

CONCLUSIONS

These observations demonstrate the possibility of the safety and usefulness of TMP-SMX treatment in patients with AIN.

White blood cell defects: molecular discoveries and clinical management

In this review, we present the most recent discoveries at the molecular level in white blood cell defects, and explain how their identification helped us to understand the underlying pathophysiology and directed our approach in clinical management. These lately discovered genes, relevant to immune disorders of mononuclear phagocytes and neutrophils, include defects in the interferon gamma (IFNg)/interleukin 12 (IL-12) pathway, such as IFNg receptor (IFNgR) defects, IL-12 defect, IL-12 receptor (IL-12R) defect, and signal transducer and activator of transcription 1 (STAT-1) defect. We have also included NF-kappaB essential modifier (NEMO) defects, which lead to X-linked ectodermal dysplasia, with or without lymphedema and osteopetrosis, and a wide range of involvement of the immune system, which can mimic the hyper-IgM phenotype. Neutrophil-specific granule deficiency and neutrophil elastase deficiency are discussed, the latter being the molecular defect in both cyclic neutropenia and in some sporadic cases of severe congenital neutropenia.

Significance of the detection of antineutrophil antibodies in children with chronic neutropenia

We evaluated the clinical characteristics of 41 children with chronic neutropenia based on the quantitative analysis of antineutrophil antibodies in serum by flow cytometry. According to the strength of antineutrophil antibodies, the patients were divided into 3 groups: 12 patients presented negative antibodies, 13 patients showed weak positive antibodies, and 16 patients showed strong positive antibodies. No significant differences were seen in age of diagnosis, severity of neutropenia, and infectious complications associated with neutropenia among the 3 groups. The spontaneous resolution of neutropenia was observed in all patients with negative antibodies and in 22 of 29 patients with positive antibodies. The age of the recovery of neutropenia and the duration until spontaneous resolution of neutropenia were significantly dependent on the antibody strength at the time of diagnosis. These results demonstrate that the quantification of antineutrophil antibodies at the time of diagnosis may be useful in considering the clinical course of chronic neutropenia in childhood.

The association of Buschke-Ollendorf syndrome and nail-patella syndrome

Buschke-Ollendorf syndrome and nail-patella syndrome are both rare connective tissue disorders inherited in an autosomal dominant pattern and characterized by cutaneous and bone lesions. We describe a 3-year-old boy and his family who showed clinical features of both Buschke-Ollendorf syndrome and nail-patella syndrome. To our knowledge, this association has not been reported previously, suggesting that these two connective tissue disorders may share the same gene location with different mutations or involve different mutated genes that share downstream segments of their signaling pathways. Furthermore, this young patient is also affected by a chronic idiopathic neutropenia usually not observed in Buschke-Ollendorf syndrome or nail-patella syndrome.

Neutrophil disorders and their management

Neutrophil disorders are an uncommon yet important cause of morbidity and mortality in infants and children. This article is an overview of these conditions, with emphasis on clinical recognition, rational investigation, and treatment. A comprehensive list of references is provided for further reading.

White blood cells 1: non-malignant disorders

Disorders of white cells are very common in clinical practice. White-cell development and numbers are controlled by a mixture of external stimuli including cytokines, matrix proteins, and accessory cells. Several different white-cell lineages are recognised; each has a role in host defence. Both white-cell deficiency and overproduction can lead to disease. Some forms of inherited white-cell deficiency are potentially treatable with gene therapy.

Defective Proliferation of Primitive Myeloid Progenitor Cells in Patients With Severe Congenital Neutropenia

Although several mechanisms have been proposed to explain the pathophysiology of severe congenital neutropenia (SCN), the precise defect responsible for SCN remains unknown. We studied the responsiveness of primitive myeloid progenitor cells to hematopoietic factors in 4 patients with SCN. The number of granulocyte-macrophage (GM) colonies formed in patients was decreased in response to granulocyte colony-stimulating factor (G-CSF) in both serum-supplemented and serum-deprived culture. The polymerase chain reaction–single-strand conformational polymorphism analysis of the G-CSF receptor gene showed no variance in structure conformation between the 4 patients and the normal subjects. In patients with SCN, the nonadherent light density bone marrow cells and cells that were purified on the basis of the expression of CD34 and Kit receptor (CD34+/Kit+ cells) showed the reduced response to the combination of steel factor (SF), the ligand for flk2/flt3 (FL), and interleukin-3 (IL-3) with or without G-CSF in serum-deprived culture. Furthermore, when individual CD34+/Kit+ cells from patients were cultured in the presence of SF, FL, and IL-3, with or without G-CSF for 10 days, the number of clones proliferated and the number of cells per each proliferating clone was significantly less than those in normal subjects. These results suggest that primitive myeloid progenitor cells of patients with SCN have defective responsiveness to not only G-CSF, but also the early- or intermediate-acting hematopoietic factors, SF, FL, and IL-3.

Defective Proliferation of Primitive Myeloid Progenitor Cells in Patients With Severe Congenital Neutropenia

Although several mechanisms have been proposed to explain the pathophysiology of severe congenital neutropenia (SCN), the precise defect responsible for SCN remains unknown. We studied the responsiveness of primitive myeloid progenitor cells to hematopoietic factors in 4 patients with SCN. The number of granulocyte-macrophage (GM) colonies formed in patients was decreased in response to granulocyte colony-stimulating factor (G-CSF) in both serum-supplemented and serum-deprived culture. The polymerase chain reaction–single-strand conformational polymorphism analysis of the G-CSF receptor gene showed no variance in structure conformation between the 4 patients and the normal subjects. In patients with SCN, the nonadherent light density bone marrow cells and cells that were purified on the basis of the expression of CD34 and Kit receptor (CD34+/Kit+ cells) showed the reduced response to the combination of steel factor (SF), the ligand for flk2/flt3 (FL), and interleukin-3 (IL-3) with or without G-CSF in serum-deprived culture. Furthermore, when individual CD34+/Kit+ cells from patients were cultured in the presence of SF, FL, and IL-3, with or without G-CSF for 10 days, the number of clones proliferated and the number of cells per each proliferating clone was significantly less than those in normal subjects. These results suggest that primitive myeloid progenitor cells of patients with SCN have defective responsiveness to not only G-CSF, but also the early- or intermediate-acting hematopoietic factors, SF, FL, and IL-3.

Benign ethnic neutropenia: what is a normal absolute neutrophil count?

Approximately 25% to 50% of persons of African descent and some ethnic groups in the Middle East have benign ethnic neutropenia, with low leukocyte and neutrophil counts. It is important to recognize the existence of this condition, the most common form of neutropenia throughout the world, and thus avoid both under-and overevaluation. Although there is no scientific basis for an absolute neutrophil count of 1.5x10(9)/L to be considered minimal, counts below this level are empirically regarded as inadequate in persons of all ethnic groups who are above the age of 1 year. Many individuals, however, maintain consistently low absolute neutrophil counts without evidence of increased susceptibility to infection or any other adverse effect. The important determination is not how many neutrophils are present in the peripheral blood, but whether the bone marrow is able to produce enough normally functioning cells when needed. A description of benign ethnic neutropenia, as set forth in this review, suggests that the lower limit now considered acceptable for the absolute neutrophil count should be readjusted downward for all ethnic groups.