Immune neutropenias of infancy and childhood

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.

Etiological causes and prognosis in children with neutropenia

OBJECTIVE

Neutropenia is defined as an absolute neutrophil count (ANC) below 1500/mm³ in the peripheral blood and is a common condition in childhood. In this study, underlying etiological causes and prognoses in children in follow-up due to neutropenia were analyzed to form a guide for physicians working in primary health care institutions.

METHODS

The medical records of pediatric patients who were followed up as an inpatients or outpatients due to neutropenia between October 2014 and October 2017 were reviewed retrospectively.

RESULTS

A total of 94 patients were included in the study with a median age of 24 (8-77) months. The median ANC at the time of admission was 600 (300-970)/mm³. The ANC was 0-500/mm³ in 34 patients (36.2%), 500-1000/mm³ in 36 patients (38.3%), and 1000-1500/mm³ in 24 patients (25.5%). Of the total, 43 patients (45.7%) were followed up as inpatients and 51 (54.3%) were followed as outpatients. Fifty-five patients (58.5%) were diagnosed with post-infectious neutropenia. The most common focus of infection was the upper respiratory airway (38.4%). The etiological cause could not be identified in 23 (24.6%) patients, neutropenia developed during drug use in 6 patients (6.3%), 5 patients (5.3%) were diagnosed with Vitamin B12 deficiency (Vitamin B12 level: 168 [129-174] pg/ml, the levels were studied in 48 patients), 2 patients (2%) were diagnosed with chronic benign neutropenia, 1 patient (1.1%) was diagnosed with immune deficiency, 1 patient (1.1%) was diagnosed with autoimmune lymphoproliferative syndrome, and 1 patient (1.1%) was diagnosed with hemophagocytic lymphohistiocytosis secondary to a previous infection. No patient was diagnosed with congenital neutropenia. A total of 91 patients (96.8%) recovered from the neutropenia. Neutropenia did not improve in 3 patients (3.2%). One patient was lost due to infection.

CONCLUSION

Etiological cause can be shown in approximately 75% of neutropenic children. The most common etiological cause is infection. Drug use, nutritional deficiencies, and chronic benign neutropenia are less common causes of neutropenia. The clinical course is largely benign and the mortality rate is very low.

Possible involvement of regulatory T cell abnormalities and variational usage of TCR repertoire in children with autoimmune neutropenia

Autoimmune neutropenia (AIN) in childhood is characterized by chronic neutropenia and positivity for anti-neutrophil antibodies, resulting in the excessive destruction of neutrophils. In this study, we investigated the involvement of regulatory T cells (T_regs ) in the pathogenesis of AIN in childhood. T_regs have been classified into three subpopulations based on the expressions of CD45RA and forkhead box protein 3 (FoxP3): resting T_regs , activated T_regs and non-suppressive T_regs . The frequency of activated T_regs (CD4⁺ CD25⁺ FoxP3^high CD45RA^- T cells) as well as that of total T_regs (CD4⁺ CD25⁺ FoxP3⁺ T cells) in peripheral blood was significantly decreased in patients with AIN. Analysis of the T cell receptor (TCR)-Vβ repertoire of CD4⁺ T cells revealed skewed usages in patients with AIN compared with that observed in age-matched control subjects. Regarding T cell subsets, the use of four of 24 TCR-Vβ families in T_regs and one in conventional T cells were increased in patients with AIN. The number of patients with AIN who showed skewed usages of TCR-Vβ family in conventional and T_regs was significantly higher than that reported in control subjects. When the preference between T_regs and conventional T cells in each TCR-Vβ family was individually compared, different use was prominently observed in the TCR-Vβ 9 family in patients with AIN. These results suggest that the quantitative abnormalities of T_regs and the skew of the TCR-Vβ repertoire in CD4⁺ T cells, including T_regs and conventional T cells, may be related to autoantibody production through a human neutrophil antigen-reactive T cell clone.

An overview of how on-call consultant paediatricians can recognise and manage severe primary immunodeficiencies

Severe primary paediatric immunodeficiency syndromes are rare and potentially fatal unless suspected, diagnosed and treated early. We provide clinical guidance and support for on-call consultant paediatricians working in secondary level hospitals on how to recognise and manage children with these conditions. Our paper addresses four conditions that risk the most severe outcomes if they are not adequately cared for during on-call periods, such as weekends: severe combined immunodeficiency, haemophagocytic lymphohistiocytosis, severe congenital neutropaenia and chronic granulomatous disease. CONCLUSION: On-call paediatricians are provided with advice on handling the most severe primary immunodeficiencies.

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.