Neutropenia associated with primary immunodeficiency syndromes

Competency of Jeffrey Modell Foundation warning signs and routine laboratory tests in suspecting primary immunodeficiencies: A cross-sectional multi-centric prospective study from eastern India

AIM

To test the efficaciousness of the 10 warning signs of Jeffrey Modell Foundation (JMF) and routine laboratory tests in predicting Primary Immunodeficiencies (PIDs).

METHODS

Hospitalized children <12 years age satisfying at least two of 10 warning signs were subjected to routine and confirmatory tests.

RESULTS

Of 35 204 admitted patients, 66 satisfied the JMF criteria and 34 had PID. Also, 59% were infants, with a female preponderance. The most common immunodeficiency disorder group were antibody deficiencies and phagocyte defects (35.3%). Chronic granulomatous disease (CGD) was the commonest overall (29.4%). The need for intravenous antibiotics was the most sensitive (91%) criterion for predicting PID. When combined with positive family history of PID, sensitivity (94%) increased further. The two most specific indicators were recurrent ear infections (88%), and family history of PID (88%). The best positive predictor was family history of PID (69%), and the best negative predictor was recurrent sinus infections (58%). Significant association was found between persistent oral thrush and PID (p .043), and insufficient weight gain and antibody deficiencies (p .037). Absolute neutrophil count, CRP, and elevated ESR were also significantly associated with PIDs (p-values being .036, .011, and .014 respectively).

CONCLUSION

Out of all 10 JMF criteria, the three most important ones to predict PID were need for IV antibiotics, family history of PID, and recurrent ear infections.

Congenital neutropenia: From lab bench to clinic bedside and back

Neutropenia is a hematological condition characterized by a decrease in absolute neutrophil count (ANC) in peripheral blood, typically classified in adults as mild (1-1.5 × 109/L), moderate (0.5-1 × 109/L), or severe (< 0.5 × 109/L). It can be categorized into two types: congenital and acquired. Congenital severe chronic neutropenia (SCN) arises from mutations in various genes, with different inheritance patterns, including autosomal recessive, autosomal dominant, and X-linked forms, often linked to mitochondrial diseases. The most common genetic cause is alterations in the ELANE gene. Some cases exist as non-syndromic neutropenia within the SCN spectrum, where genetic origins remain unidentified. The clinical consequences of congenital neutropenia depend on granulocyte levels and dysfunction. Infants with this condition often experience recurrent bacterial infections, with approximately half facing severe infections within their first six months of life. These infections commonly affect the respiratory system, digestive tract, and skin, resulting in symptoms like fever, abscesses, and even sepsis. The severity of these symptoms varies, and the specific organs and systems affected depend on the genetic defect. Congenital neutropenia elevates the risk of developing acute myeloid leukemia (AML) or myelodysplastic syndromes (MDS), particularly with certain genetic variants. SCN patients may acquire CSF3R and RUNX1 mutations, which can predict the development of leukemia. It is important to note that high-dose granulocyte colony-stimulating factor (G-CSF) treatment may have the potential to promote leukemogenesis. Treatment for neutropenia involves antibiotics, drugs that boost neutrophil production, or bone marrow transplants. Immediate treatment is essential due to the heightened risk of severe infections. In severe congenital or cyclic neutropenia (CyN), the primary therapy is G-CSF, often combined with antibiotics. The G-CSF dosage is gradually increased to normalize neutrophil counts. Hematopoietic stem cell transplants are considered for non-responders or those at risk of AML/MDS. In cases of WHIM syndrome, CXCR4 inhibitors can be effective. Future treatments may involve gene editing and the use of the diabetes drug empagliflozin to alleviate neutropenia symptoms.

Neutropenia Is an Underrecognized Finding in Pediatric Primary Immunodeficiency Diseases: An Analysis of the United States Immunodeficiency Network Registry

BACKGROUND

The frequency of neutropenia in pediatric primary immunodeficiency disorders (PIDDs) is unknown and potentially underappreciated. Our study aimed to determine the overall frequency and severity of neutropenia in children diagnosed with a PIDD entered in the United States Immunodeficiency Network (USIDNET) patient registry.

PROCEDURE

Neutropenia data and demographic/clinical information from 1145 patients younger than 21 years of age was obtained from the USIDNET registry.

RESULTS

Neutropenia is more common in PIDD patients entered within the USIDNET registry than previously appreciated. There was a >10% occurrence rate of neutropenia in all broad primary immunodeficiency categories as well as in nearly all individual PIDDs. Neutropenia frequency was greater in African American pediatric PIDD patients than in white or Asian patients. The degree of neutropenia did not associate with mortality in pediatric patients with a PIDD.

CONCLUSION

Although our study did not assess the frequency of PIDD in patients presenting with neutropenia, the possibility of a primary immune disorder should be considered in patients with idiopathic neutropenia.

The evaluation of neutropenia in common variable immune deficiency patients

Objectives: Common variable immunodeficiency is a primary immunodeficiency disease characterized by hypogammaglobulinemia and heterogeneous clinical features. Neutropenia is a rare complication among CVID patients leading to a higher rate of infections and morbidity. Multiple factors (e.g. autoimmunity, infections, drugs and etc.) are found to underlie this complication.Methods: In the present study, demographic, clinical and laboratory data were compared between two groups of CVID patients with and without neutropenia.Results: Frequency of neutropenia was 8.1%. Infectious complications were the most prevalent clinical manifestations regardless of presence of neutropenia. However, candida infection and septicemia were significantly higher in neutropenic patients (p = 0.001 and p = 0.01, respectively). The most prominent clinical phenotypes of CVID patients with neutropenia were polyclonal lymphocytic infiltration and autoimmunity, both being considerably higher compared to the non-neutropenic group (p = 0.04 and p = 0.009, respectively). The mortality rate in neutropenic patients was higher than in patients without neutropenia (61.1 vs. 25.2%, p = 0.004).Conclusion: Although neutropenia is a rare complication among CVID patients, it is associated with frequent and severe clinical complications, including autoimmunity and lymphoproliferative conditions. Also, its accompaniment with higher mortality frequency in CVID patients indicates a need for more precise attention and consideration regarding specific treatment in neutropenic patients.

Multiparametric Whole Blood Dissection: A one-shot comprehensive picture of the human hematopoietic system

Human hematopoiesis is a complex and dynamic system where morphologically and functionally diverse mature cell types are generated and maintained throughout life by bone marrow (BM) Hematopoietic Stem/Progenitor Cells (HSPC). Congenital and acquired hematopoietic disorders are often diagnosed through the detection of aberrant frequency or composition of hematopoietic cell populations. We here describe a novel protocol, called “Whole Blood Dissection” (WBD), capable of analyzing in a single test‐tube, hematopoietic progenitors and all major mature cell lineages composing either BM or peripheral blood (PB) through a multiparametric flow‐cytometry analysis. WBD allows unambiguously identifying in the same tube up to 23 different blood cell types including HSPC subtypes and all the major myeloid and lymphoid lineage compartments at different stages of maturation, through a combination of 17 surface and 1 viability cell markers. We assessed the efficacy of WBD by analyzing BM and PB samples from adult (n = 8) and pediatric (n = 9) healthy donors highlighting age‐related shift in cell composition. We also tested the capability of WBD on detecting aberrant hematopoietic cell composition in clinical samples of patients with primary immunodeficiency or leukemia unveiling expected and novel hematopoietic unbalances. Overall, WBD allows unambiguously identifying >99% of the cell subpopulations composing a blood sample in a reproducible, standardized, cost‐, and time‐efficient manner. This tool has a wide range of potential pre‐clinical and clinical applications going from the characterization of hematopoietic disorders to the monitoring of hematopoietic reconstitution in patients after transplant or gene therapy. © 2017 The Authors. Cytometry Part A Published by Wiley Periodicals, Inc. on behalf of ISAC.

Intravenous immunoglobulin replacement treatment does not alter polymorphonuclear leukocytes function and surface receptors expression in patients with common variable immunodeficiency

The study of the expression of CD16, CD11b and Siglec 9 receptors and the oxidative burst provides insights on polymorphonuclear leukocytes (PMN) functionality in common variable immunodeficiency (CVID) and on the possible effects of intravenous immunoglobulin (IVIg) infusion. We evaluated in vivo before and soon after IVIg administration the CD16, CD11b and Siglec 9 expression on unstimulated and Escherichia coli-stimulated PMN and the oxidative burst induced by Escherichia coli and PMA. The E. coli stimulation up-regulated CD16 and Siglec 9 expression and it induced a strong CD11b up-regulation at baseline and soon after IVIg. The oxidative burst overlapped that observed in healthy donors when induced by Escherichia coli while it increased when induced by PMA. Soon after IVIg infusion, the oxidative burst decreased only when induced by PMA. Our results showed that the IVIg infusion in vivo had a minimal effect on CVID's PMN.

[X-linked agammaglobulinemia: experience in a Portuguese hospital]

INTRODUCTION

X-Linked agammaglobulinemia (XLA) is characterized by an arrest of B cell differentiation, leading to recurrent bacterial infections. Lifelong immunoglobulin replacement therapy (IRT) is indicated to prevent infections and their complications.

MATERIAL AND METHODS

A retrospective study of patients with XLA followed in a level three hospital was performed; data was collected retrospectively by review of clinical files.

RESULTS

XLA was diagnosed in 9 children. One (11%) had a positive family history with a prenatal diagnosis. Infection was the clinical presentation in all the others (89%), at an average age of 13 months; diagnosis was established at a mean age of 3.4 years. Acute otitis media (7/9) and pneumonia (5/9) were the most frequently observed. Seven (78%) presented serum immunoglobulin G (IgG) levels below 200mg/dL and all of them had CD19(+) B cells below 2%. Neutropenia was present at diagnosis in three patients (33%). Bruton tyrosine kinase (BTK) mutations were identified in all cases. Intravenous IRT was initiated, switched later to subcutaneous administration, in all. The mean time of follow-up was 10.7 years with cumulative time of 97 years. Eight children (89%) achieved IgG serum levels above 800 mg/dL. One presented lower values due to renal loss. No deaths occurred. After diagnosis the most frequent infections were acute otitis media (6/9). In spite of stable adequate IgG levels on IRT, two patients developed bronchiectasis.

CONCLUSIONS

XLA overall prognosis is good, as long as patients have an early and adequate treatment. However, bronchiectasis can occur even on adequate immunoglobulin replacement therapy.

Clinical and mutational features of Vietnamese children with X-linked agammaglobulinemia

BACKGROUND

X-linked agammaglobulinemia (XLA) is a primary immune deficiency characterized by recurrent bacterial infections and profoundly depressed serum immunoglobulin levels and circulating mature B cells. It is caused by mutations of the Bruton tyrosine kinase (BTK) gene and is the most common form of inherited antibody deficiency. To our knowledge, this is the first report of XLA from Vietnam.

METHODS

We investigated the BTK gene mutations and clinical features of four unrelated Vietnamese children.

RESULTS

The mean ages at onset and at diagnosis were 2.5 and 8 years, respectively. All patients had a medical history of otitis media, pneumonia, and septicemia at the time of diagnosis. Other infections reported included sinusitis, bronchiectasis, arthritis, skin infections, meningitis, and recurrent diarrhea. We identified one previously reported mutation (c.441G >A) and three novel mutations: two frameshifts (c.1770delG and c.1742 delG), and one nonsense (c.1249A >T).

CONCLUSIONS

The delayed diagnosis may be attributable to insufficient awareness of this rare disease on the background of frequent infections even in the immunocompetent pediatric population in Vietnam. Our results further support the importance of molecular genetic testing in diagnosis of XLA.

Spectrum of bone marrow failures of myeloid series: new report of neutropenic patients from a referral pediatric center in Iran

Neutropenia is a reduction of the absolute neutrophil count (ANC), which could be seen in different conditions, while its association with a number of primary immunodeficiency diseases has been reported. This study was performed in all neutropenic patients who were admitted in a referral pediatric hospital during a 6-year period (2006-2011). One hundred and forty patients with ANC of below 1500/mm(3) were investigated in this study. The most common causes of neutropenia were severe congenital neutropenia (41%), aplastic anemia (19%), cyclic neutropenia (11%), hyperimmunoglobulin M syndrome (9%), and fanconi anemia (7%). The patients experienced their first manifestation at a median age of 1 year, while the median diagnostic age was 21 months. Parental consanguinity was present in about half of the cases. The most common clinical manifestations of the patients were sinusitis (62 cases), periodontitis (51 cases), acute diarrhea (39 cases), pneumonia (38 cases), abscess (36 cases), skin rashes (35 cases), and otitis media (31 cases). Twenty two patients (16%) died during the study period. Considering the differential diagnosis of neutropenia, making the diagnosis and appropriate treatments are the keys in management of patients with neutropenia to avoid further complications.

A new mutation that predicted a drastic alteration of the BTK protein function

X-linked agammaglobulinemia (XLA) or Bruton disease is a relatively rare constitutionally immune disorder due to a genetic mutation of BTK (Bruton tyrosine kinase) gene which encodes for BTK protein. BTK is a signal-transducing protein expressed in hematopoietic lineages. The genetic disorder is responsible for B cell lymphocytes' maturation arrest. The humoral immunodeficiency caused by BTK mutation is linked with recurrent bacterial and viral infections. Genetic investigations of the prepositus as well as the other members of the family are necessary to characterize a mutation in BTK gene to confirm the diagnosis and reveal a hereditary transmission or de novo mutation. Authors propose and comment a case report of an 8 month old child who suffers from Bruton disease. Initial presentation was neutropenia, but genetic investigation has revealed a previously non-reported mutation in the BTK gene. The same mutation was found in the mother with low expression of BTK in monocytes and normal in B-cells suggesting a lineage specific extinction of BTK which has never been reported before.

Neutropenia in primary immunodeficiency

PURPOSE OF REVIEW

Neutropenia is a feature of several primary immunodeficiency diseases (PIDDs). Because of the diverse pathophysiologies of the PIDDs and the rarity of each disorder, data are often lacking, leading to the necessity of empiric treatment. Recent developments in the understanding of neutropenia in several of the PIDDs make a review of the data timely.

RECENT FINDINGS

The category of severe congenital neutropenia continues to expand. Mutations in G6PC3 have been identified as the cause of neutropenia in a minority of previously molecularly undefined cases. Recent advances have broadened our understanding of the pathophysiology and the clinical expression of this disorder. A possible function of the C16orf57 gene has been hypothesized that may explain the clinical overlap between Clerucuzio-type poikiloderma with neutropenia and other marrow diseases. Plerixafor has been shown to be a potentially useful treatment in the warts, hypogammaglobulinemia, infection, and myelokathexis syndrome. Investigations of patients with adenosine deaminase deficient severe combined immunodeficiency have identified neutropenia, and particularly susceptibility to myelotoxins, as a feature of this disorder. Granulocyte-colony stimulating factor is the treatment of choice for neutropenia in PIDD, whereas hematopoietic cell transplantation is the only curative option.

SUMMARY

The number of PIDDs associated with neutropenia has increased, as has our understanding of the range of phenotypes. Additional data and hypotheses have been generated helping to explain the diversity of presentations of neutropenia in PIDDs.

How to approach neutropenia

Neutropenia is defined as the reduction in the absolute number of neutrophils in the blood circulation. Acute neutropenia is a relatively frequent finding, whereas disorders of production of neutrophils are quite rare. Acute neutropenia is often well tolerated and normalizes rapidly. Neutropenia arising as a result of underlying hematologic disorders is far more significant. Such a patient may be at risk for infectious complications and will likely require a thorough investigation. Acute neutropenia evolves over a few days and occurs when neutrophil use is rapid and production is impaired. Chronic neutropenia may last for 3 months or longer and is a result of reduced production, increased destruction, or excessive splenic sequestration of neutrophils. Neutropenia may be classified by whether it arises secondarily to causes extrinsic to BM myeloid cells, which is common; as an acquired disorder of myeloid progenitor cells, which is less frequent; or as an intrinsic defect arising from impaired proliferation and maturation of myeloid progenitor cells in the BM, which is rare. Severe neutropenia with absolute neutrophil counts below 500/μL increases susceptibility to bacterial or fungal infections. Multiple disorders of severe congenital neutropenia have been found by the discovery of genetic defects affecting differentiation, adhesion, and apoptosis of neutrophil precursors. Elucidation of the multiple genetic defects have provided insight into the biology of the cell involving membrane structures, secretory vesicles, mitochondrial metabolism, ribosome biogenesis, transcriptional regulation, and cytoskeletal dynamics, as well as the risk for myelodysplasia and acute myeloid leukemia.

A differential concentration-dependent effect of IVIg on neutrophil functions: relevance for anti-microbial and anti-inflammatory mechanisms

BACKGROUND

Polymorphonuclear neutrophils (PMN) play a key role in host defences against invading microorganisms but can also potentiate detrimental inflammatory reactions in case of excessive or misdirected responses. Intravenous immunoglobulins (IVIg) are used to treat patients with immune deficiencies and, at higher doses, in autoimmune, allergic and systemic inflammatory disorders.

METHODOLOGY/PRINCIPAL FINDINGS

We used flow cytometry to examine the effects of IVIg on PMN functions and survival, using whole-blood conditions in order to avoid artifacts due to isolation procedures. IVIg at low concentrations induced PMN activation, as reflected by decreased L-selectin and increased CD11b expression at the PMN surface, oxidative burst enhancement, and prolonged cell survival. In contrast, IVIg at higher concentrations inhibited LPS-induced CD11b degranulation and oxidative burst priming, and counteracted LPS-induced PMN lifespan prolongation.

CONCLUSIONS/SIGNIFICANCE

IVIg appears to have differential, concentration-dependent effects on PMN, possibly supporting the use of IVIg as either an anti-microbial or an anti-inflammatory agent.

Congenital and acquired neutropenia consensus guidelines on diagnosis from the Neutropenia Committee of the Marrow Failure Syndrome Group of the AIEOP (Associazione Italiana Emato-Oncologia Pediatrica)

Congenital and acquired neutropenia are rare disorders whose frequency in pediatric age may be underestimated due to remarkable differences in definition or misdiagnosed because of the lack of common practice guidelines. Neutropenia Committee of the Marrow Failure Syndrome Group (MFSG) of the AIEOP (Associazione Italiana Emato-Oncologia Pediatrica) elaborated this document following design and methodology formerly approved by the AIEOP board. The panel of experts reviewed the literature on the topic and participated in a conference producing a document which includes a classification of neutropenia and a comprehensive guideline on diagnosis of neutropenia.

Congenital neutropenia: diagnosis, molecular bases and patient management

The term congenital neutropenia encompasses a family of neutropenic disorders, both permanent and intermittent, severe (<0.5 G/l) or mild (between 0.5-1.5 G/l), which may also affect other organ systems such as the pancreas, central nervous system, heart, muscle and skin. Neutropenia can lead to life-threatening pyogenic infections, acute gingivostomatitis and chronic parodontal disease, and each successive infection may leave permanent sequelae. The risk of infection is roughly inversely proportional to the circulating polymorphonuclear neutrophil count and is particularly high at counts below 0.2 G/l.When neutropenia is detected, an attempt should be made to establish the etiology, distinguishing between acquired forms (the most frequent, including post viral neutropenia and auto immune neutropenia) and congenital forms that may either be isolated or part of a complex genetic disease.Except for ethnic neutropenia, which is a frequent but mild congenital form, probably with polygenic inheritance, all other forms of congenital neutropenia are extremely rare and have monogenic inheritance, which may be X-linked or autosomal, recessive or dominant.About half the forms of congenital neutropenia with no extra-hematopoietic manifestations and normal adaptive immunity are due to neutrophil elastase (ELANE) mutations. Some patients have severe permanent neutropenia and frequent infections early in life, while others have mild intermittent neutropenia.Congenital neutropenia may also be associated with a wide range of organ dysfunctions, as for example in Shwachman-Diamond syndrome (associated with pancreatic insufficiency) and glycogen storage disease type Ib (associated with a glycogen storage syndrome). So far, the molecular bases of 12 neutropenic disorders have been identified.Treatment of severe chronic neutropenia should focus on prevention of infections. It includes antimicrobial prophylaxis, generally with trimethoprim-sulfamethoxazole, and also granulocyte-colony-stimulating factor (G-CSF). G-CSF has considerably improved these patients' outlook. It is usually well tolerated, but potential adverse effects include thrombocytopenia, glomerulonephritis, vasculitis and osteoporosis. Long-term treatment with G-CSF, especially at high doses, augments the spontaneous risk of leukemia in patients with congenital neutropenia.

T and B lymphocyte abnormalities in bone marrow biopsies of common variable immunodeficiency

In common variable immunodeficiency (CVID) defects in early stages of B-cell development, bone marrow (BM) plasma cells and T lymphocytes have not been studied systematically. Here we report the first morphologic and flow cytometric study of B- and T-cell populations in CVID BM biopsies and aspirates. Whereas the hematopoietic compartment showed no major lineage abnormalities, analysis of the lymphoid compartment exhibited major pathologic alterations. In 94% of the patients, BM plasma cells were either absent or significantly reduced and correlated with serum immunoglobulin G levels. Biopsies from CVID patients had significantly more diffuse and nodular CD3(+) T lymphocyte infiltrates than biopsies from controls. These infiltrates correlated with autoimmune cytopenia but not with other clinical symptoms or with disease duration and peripheral B-cell counts. Nodular T-cell infiltrates correlated significantly with circulating CD4(+)CD45R0(+) memory T cells, elevated soluble IL2-receptor and neopterin serum levels indicating an activated T-cell compartment in most patients. Nine of 25 patients had a partial block in B-cell development at the pre-B-I to pre-B-II stage. Because the developmental block correlates with lower transitional and mature B-cell counts in the periphery, we propose that these patients might form a new subgroup of CVID patients.

Children with frequent infections: a proposal for a stepwise assessment and investigation of the immune system

Although many children develop frequent infections, only a few have an underlying immune disorder. Children with dysfunction of the immune system develop frequent infections and/or recurrent, persistent, severe, and rare infections. The aim of this review is to provide to the clinician a valuable tool for recognizing any 'discords' of the 'immune-system symphonic orchestra'. By following a reverse route, it will be possible to brighten up the dark and winding road of immunodeficiencies and identify the exact point of immune dysfunction. This is fundamental and crucial to perceive etiologic management and subsequently achieve the best for these young patients and their families.

Congenic mice confirm that collagen X is required for proper hematopoietic development

The link between endochondral skeletal development and hematopoiesis in the marrow was established in the collagen X transgenic (Tg) and null (KO) mice. Disrupted function of collagen X, a major hypertrophic cartilage matrix protein, resulted in skeletal and hematopoietic defects in endochondrally derived tissues. Manifestation of the disease phenotype was variable, ranging from perinatal lethality in a subset of mice, to altered lymphopoiesis and impaired immunity in the surviving mice. To exclude contribution of strain specific modifiers to this variable manifestation of the skeleto-hematopoietic phenotype, C57Bl/6 and DBA/2J collagen X congenic lines were established. Comparable disease manifestations confirmed that the skeleto-hematopoietic alterations are an inherent outcome of disrupted collagen X function. Further, colony forming cell assays, complete blood count analysis, serum antibody ELISA, and organ outgrowth studies established altered lymphopoiesis in all collagen X Tg and KO mice and implicated opportunistic infection as a contributor to the severe disease phenotype. These data support a model where endochondral ossification-specific collagen X contributes to the establishment of a hematopoietic niche at the chondro-osseous junction.

Neutropenia in antibody-deficient patients under IVIG replacement therapy

Patients with antibody deficiencies are more prone to develop acute neutropenic episodes even during immunoglobulin replacement. The aims of this study were to evaluate the presence of acute neutropenia in 42 patients with primary antibody immunodeficiencies, currently receiving intravenous immunoglobulin (IVIG), and to describe the clinical and laboratory findings during neutropenic episodes. Of all patients, 10 (23.8%) presented acute neutropenia (absolute neutrophil count <1500 cells/mm3) during follow up (mean of 6.4 yr). The absolute neutrophil count ranged from 71 to 1488 cells/mm3. Neutropenia was not clearly associated with antibiotic prophylactic therapy or immunoglobulin levels, while infections were associated with neutropenia in the majority of episodes. Most acute neutropenia episodes were mild or moderate, except in CVID patients who present more severe neutropenia. Although IVIG may have contributed to reducing the severity of neutropenia, it does not prevent its occurrence in all patients. In conclusion, primary immunodeficient patients, even submitted to IVIG replacement therapy, must be regularly evaluated for neutropenia in order to minimize the risk of infections and its appropriate approach.

Altered endochondral ossification in collagen X mouse models leads to impaired immune responses

Disruption of collagen X function in hypertrophic cartilage undergoing endochondral ossification was previously linked to altered hematopoiesis in collagen X transgenic (Tg) and null (KO) mice (Jacenko et al., [2002] Am J Pathol 160:2019-2034). Mice displayed altered growth plates, diminished trabecular bone, and marrow hypoplasia with an aberrant lymphocyte profile throughout life. This study identifies altered B220+, CD4+, and CD8+ lymphocyte numbers, as well as CD4+/fox3P+ T regulatory cells in the collagen X mice. Additionally, diminished in vitro splenocyte responses to mitogens and an inability of mice to survive a challenge with Toxoplasma gondii, confirm impaired immune responses. In concert, ELISA and protein arrays identify aberrant levels of inflammatory, chemo-attractant, and matrix binding cytokines in collagen X mouse sera. These data link the disruption of collagen X function in the chondro-osseous junction to an altered hematopoietic stem cell niche in the marrow, resulting in impaired immune function.

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.

APRIL secreted by neutrophils binds to heparan sulfate proteoglycans to create plasma cell niches in human mucosa

The bone marrow constitutes a favorable environment for long-lived antibody-secreting plasma cells, providing blood-circulating antibody. Plasma cells are also present in mucosa-associated lymphoid tissue (MALT) to mediate local frontline immunity, but how plasma cell survival there is regulated is not known. Here we report that a proliferation-inducing ligand (APRIL) promoted survival of human upper and lower MALT plasma cells by upregulating expression of the antiapoptotic proteins bcl-2, bcl-xL, and mcl-1. The in situ localization of APRIL was consistent with such a prosurvival role in MALT. In upper MALT, tonsillar epithelium produced APRIL. Upon infection, APRIL production increased considerably when APRIL-secreting neutrophils recruited from the blood infiltrated the crypt epithelium. Heparan sulfate proteoglycans (HSPGs) retained secreted APRIL in the subepithelium of the infected zone to create APRIL-rich niches, wherein IgG-producing plasma cells accumulated. In lower MALT, neutrophils were the unique source of APRIL, giving rise to similar niches for IgA-producing plasmocytes in villi of lamina propria. Furthermore, we found that mucosal humoral immunity in APRIL-deficient mice is less persistent than in WT mice. Hence, production of APRIL by inflammation-recruited neutrophils may create plasma cell niches in MALT to sustain a local antibody production.

Clinical immunology review series: an approach to the patient with recurrent infections in childhood

Recurrent or persistent infection is the major manifestation of primary immunodeficiency, which also results in atypical infection with opportunistic organisms. Young children are also vulnerable to infection and recurrent infection is common. While most children with recurrent infection have a normal immunity, it is important to recognize the child with an underlying primary immunodeficiency and investigate and treat appropriately and yet not over investigate normal children. Prompt, accurate diagnosis directs the most appropriate treatment, and early and judicious use of prophylactic antibiotics and replacement immunoglobulin can prevent significant end organ damage and improve long-term outlook and quality of life. This paper describes important presenting features of primary immunodeficiency and indicates when further investigation is warranted.

A molecular classification of congenital neutropenia syndromes

Current knowledge on the molecular pathogenesis of severe congenital neutropenia indicates that the clinical diagnosis includes a heterogeneous group of disorders following different patterns of inheritance. Similarly, multifaceted syndromes associated with neutropenia can be classified molecularly, which in turn allows for a better understanding of the basis of the neutropenia. Many of the neutropenia disorders can be treated with G-CSF (filgrastim) to increase the neutrophil count, thereby reducing infection morbidity and mortality. In some instances hematopoietic stem cell transplantation remains the only curative treatment currently available. This review describes and classifies, on a molecular basis, both primary congenital neutropenia and multifaceted syndromes associated with neutropenia.

X-linked agammaglobulinemia: report on a United States registry of 201 patients

X-linked agammaglobulinemia (XLA) is a primary immunodeficiency caused by mutations in the gene for Bruton tyrosine kinase (BTK) that result in the deficient development of B lymphocytes and hypogammaglobulinemia. Because the disorder is uncommon, no single institution has had sufficient numbers of patients to develop a comprehensive clinical picture of the disorder. Accordingly, a national registry of United States residents with XLA was established in 1999 to provide an updated clinical view of the disorder in a large cohort of patients. A total of 201 patients were registered by 66 physicians. The estimated birth rate for the 10-year period of 1988-1997 was 1/379,000. Infection was the most common initial clinical presentation (85%), followed by a positive family history (41%) and neutropenia (11%). Although the average age of diagnosis was younger in patients with a positive family history (mean, 2.59 yr) than in patients with a negative family history (mean, 5.37 yr) (p < 0.001), only 34.5% of patients with a positive family history at the time of their birth were diagnosed before clinical symptoms developed-that is, based on family history alone. Seventy percent of patients had at least 1 episode of otitis, 62% at least 1 episode of pneumonia, 60% at least 1 episode of sinusitis, 23% at least 1 episode of chronic/recurrent diarrhea, 21% at least 1 episode of conjunctivitis, 18% at least 1 episode of pyoderma and/or cellulitis, 11% at least 1 episode of meningitis/encephalitis, 10% at least 1 episode of sepsis, 8% at least 1 episode of septic arthritis, 6% at least 1 episode of hepatitis, and 3% at least 1 episode of osteomyelitis. Fourteen of 201 (6.9%) patients were dead at the time they were entered in the Registry. However, in a prospective 4 /4-year follow-up of living patients, only 3/80 (3.75%) patients died. Causes of death included disseminated enterovirus infection (n = 6), pulmonary insufficiency (n = 5), adenovirus infection (n = 1), sepsis (n = 1), acquired immunodeficiency disease syndrome (AIDS) (n = 1), myocarditis (n = 1), hepatitis (n = 2), and stem cell transplantation (n = 1).

Severe Neutropenia in Japanese Patients with X-Linked Agammaglobulinemia

X-linked agammaglobulinemia (XLA) is clinically characterized by recurrent bacterial infections during early infancy. Although it is not a phagocytic disorder, XLA is sometimes associated with neutropenia. We conducted a nation-wide survey to determine the frequency of neutropenia among Japanese XLA patients. Responses were received from 87 (86%) of 101 patients in which BTK mutations were previously identified, and of these, 16 (18%) had neutropenia. All episodes of neutropenia occurred before initiation of intravenous immunoglobulin (IVIG) replacement therapy. Two XLA patients died of multiple organ failure caused by severe neutropenia and Pseudomonas sepsis before initiation of IVIG replacement therapy. These results suggest that, in some cases, severe bacterial infections in XLA patients might be caused not only by antibody deficiencies but also by neutropenia.

Congenital neutropenia and primary immunodeficiency disorders: a survey of 26 Iranian patients

Inherited neutropenia is characterized by a decrease in the absolute number of circulating neutrophils and an increased susceptibility to infections. The current study was performed to determine the clinical and laboratory findings of Iranian patients with inherited neutropenias. Records of 26 patients (14 male, 12 female) with inherited neutropenia were reviewed in this study. The patients had been referred to Children's Medical Center, a referral center for immunodeficiency disorders in Iran, during a 22-year period (1981-2003). Primary immunodeficiency disorders of these patients were as follows: cyclic neutropenia (8 patients), Shwachman-Diamond syndrome (7 patients), Kostmann syndrome (6 patients), and Chediak-Higashi syndrome (5 patients). The mean absolute neutrophil count of patients was 398.2 +/- 259.3 cells/mm (range 74-1,152/mm) at the first visit. Twenty-one patients showed severe, four moderate, and one mild neutropenia. Sixteen of these patients had leukopenia, seven anemia, two thrombocytopenia, and one monocytosis. The most common presenting complaints in these patients were oral ulcer, otitis, pneumonia, diarrhea, cutaneous abscess, and oral candidiasis. The patients first manifested symptoms of infection suggesting neutropenia at a median age of 7.5 months (range 1 month to 10 years). During follow-up, respiratory infections developed in 24 cases, oral manifestations in 20 patients. The most common infections, in descending order of frequency, were otitis media, abscesses, pneumonia, oral ulcers, acute diarrhea, cutaneous infections, oral candidiasis, and periodontitis. Less frequent infections were sinusitis, cystitis, conjunctivitis, meningitis, and osteomyelitis. Nonspecific symptoms (hepatomegaly and splenomegaly) were also detected in 10 patients and 1 patient, respectively. Three patients died of recurrent infections. The infectious manifestations both at presentation and during follow-up in inherited neutropenia were similar. Although inherited neutropenias are rare, recurrent infections always deserves further evaluation for detecting such disorders.

Clinical and laboratory aspects of common variable immunodeficiency

Common variable immunodeficiency (CVID) is an immunological disorder characterized by defective antibody production, recurrent infections, most notably of the respiratory tract, autoimmune phenomena and cancer. Some CVID patients may also present disturbances of the cellular immune response such as a decrease in the number and proportion of different lymphocyte populations, diminished lymphoproliferative response to mitogens and antigens, altered production of cytokines, and deficient expression of cell-surface molecules. Most Brazilian CVID patients included in this study show a decrease in T and B lymphocyte counts in the peripheral blood. Furthermore, their lymphocytes are more susceptible to apoptosis following activation than normal individuals, and they have a decrease in the expression of activation molecules like CD25, CD69, CD40L and CD70. Moreover, they show a decreased synthesis of IL-4 and IL-5 in comparison with normal individuals. The increase in susceptibility to apoptosis following activation, may also be responsible for the decrease in the expression of activation molecules and CD40L, decrease in Th2 cytokines synthesis, and in the number of T and B circulating cells. In this study we discuss some of these immunological disturbances correlating them to the patients' clinical features and comparing our patients' findings to the literature.

Congenital neutropenia

Congenital neutropenia is strictly defined as neutropenia present at birth. However, it is more generally used to describe neutropenia secondary to inherited genetic mutations. This review will discuss the presentation of such children and the various causes of congenital neutropenia. In particular, it will focus on severe congenital neutropenia (SCN) and the recent discovery of mutations in the gene encoding neutrophil elastase in the majority of cases of SCN. The potential mechanisms of pathogenesis and of transformation to leukaemia will be discussed. Shwachman-Diamond Syndrome and other less common causes of congenital neutropenia will also be reviewed. Finally, an approach to the child with potential congenital neutropenia will be presented.

Granulocyte colony-stimulating factor-responsive chronic neutropenia in cartilage-hair hypoplasia

: Chronic neutropenia is common in children with cartilage-hair hypoplasia (CHH). The authors describe a 6-year-old with severe CHH, moderate neutropenia associated with serum IgG antibodies directed against Fcgamma-RIIIb (NA1/2), and frequent bacterial infections. In this patient, long-term administration of granulocyte colony-stimulating factor increased peripheral neutrophil counts and prevented recurrent hospitalizations for bacterial lower respiratory tract infections.

Pleiotropic consequences of Bruton tyrosine kinase deficiency in myeloid lineages lead to poor inflammatory responses

Bruton tyrosine kinase (Btk), a non-receptor-associated tyrosine kinase of the Tec family, appears to participate in many myeloid cell functions. We show that macrophages from X-linked immunodeficient (XID) mice lacking functional Btk cannot generate efficient bursts of reactive oxygen intermediates (ROIs). The induction of apoptotic cell death by inflammatory stimuli is also enhanced in XID macrophages. Phagocytosis of bacterial particles is only marginally affected in them. In vivo, XID mice show reduced severity of inflammatory diseases in models of experimental autoimmune encephalomyelitis (EAE), dextran sulfate sodium (DSS)-induced colitis, and carrageenan-induced acute edema. Also, polymorphonuclear neutrophil granulocytes (PMNs) in XID mice show poor ROI and nitric oxide (NO) induction, along with a reduction in PMN recruitment to peritoneal inflammation. XID mice show reduction in PMN numbers in peripheral blood, and their bone marrow shows a reduction in the numbers of both monocytic and granulocytic lineages, extending to the earliest progenitor populations. Thus, Btk is likely to play a significant role at multiple points during the development and functioning of the myeloid lineages, affecting the outcome of many infectious as well as noninfectious inflammatory events in vivo.

The X-linked hyper-IgM syndrome: clinical and immunologic features of 79 patients

The X-linked hyper-IgM (XHIGM) syndrome is an uncommon primary immunodeficiency disease caused by mutations in the gene for CD40 ligand and characterized by normal or elevated serum IgM, reduced levels of IgG and IgA, and defective T-cell function. Because of its rarity, it has been difficult for any single investigator or institution to develop a comprehensive clinical picture of this disorder. Accordingly, a national registry was developed in the United States to provide demographic, genetic, immunologic, and clinical information on a relatively large number of patients with the XHIGM syndrome.A total of 79 patients from 60 unrelated families were registered between January 1997 and July 2002. The estimated minimal incidence was approximately 1/1,030,000 live births. All of the patients had significant IgG deficiency and most had IgA deficiency, but only one-half had elevated IgM levels. Most patients presented initially with a history of an increased susceptibility to infection including Pneumocystis carinii pneumonia. The average age of diagnosis was significantly earlier in patients born into a family with a previously affected individual. However, only one-third of the patients born into a family with a previously affected individual were diagnosed exclusively because of the presence of the positive family history before any clinical symptoms developed. Over half the patients developed symptoms of immunodeficiency and were diagnosed by 1 year of age, and over 90% by 4 years of age. The most prominent clinical infections were pneumonia (81% of patients), upper respiratory infections (49%) including sinusitis (43%) and recurrent otitis (43%), recurrent/protracted diarrhea (34%), central nervous system infections (14%), sepsis (13%), cellulitis (13%), hepatitis (9%), and osteomyelitis (1%). In addition to infections caused by encapsulated bacteria, opportunistic infections were relatively common and were caused by P. carinii, members of the herpes virus family (including cytomegalovirus), Cryptosporidium, Cryptococcus, Candida, Histoplasma, and Bartonella. Sclerosing cholangitis occurred in 5 patients and in 4 of these was associated with Cryptosporidium infection. Eight patients had died at the time of their entry into the Registry; 2 of pneumonia (1 P. carinii and 1 cytomegalovirus), 2 of encephalitis (1 ECHO virus and 1 cytomegalovirus), 2 of malignancy (both hepatocellular carcinoma), 1 of sclerosing cholangitis caused by Cryptosporidium, and 1 of hemolytic uremic syndrome.