Chronic granulomatous disease (CGD) and complete myeloperoxidase deficiency both yield strongly reduced dihydrorhodamine 123 test signals but can be easily discerned in routine testing for CGD

Diagnosis of Chronic Granulomatous Disease: Strengths and Challenges in the Genomic Era

Chronic granulomatous disease (CGD) is a group of rare primary inborn errors of immunity characterised by a defect in the phagocyte respiratory burst, which leads to severe and life-threatening infective and inflammatory complications. Despite recent advances in our understanding of the genetic and molecular pathophysiology of X-linked and autosomal recessive CGD, and growth in the availability of functional and genetic testing, there remain significant barriers to early and accurate diagnosis. In the current review, we provide an up-to-date summary of CGD pathophysiology, underpinning current methods of diagnostic testing for CGD and closely related disorders. We present an overview of the benefits of early diagnosis and when to suspect and test for CGD. We discuss current and historical methods for functional testing of NADPH oxidase activity, as well as assays for measuring protein expression of NADPH oxidase subunits. Lastly, we focus on genetic and genomic methods employed to diagnose CGD, including gene-targeted panels, comprehensive genomic testing and ancillary methods. Throughout, we highlight general limitations of testing, and caveats specific to interpretation of results in the context of CGD and related disorders, and provide an outlook for newborn screening and the future.

Chronic Granulomatous Disease (CGD): Commonly Associated Pathogens, Diagnosis and Treatment

Chronic granulomatous disease (CGD) is a primary immunodeficiency caused by a defect in the phagocytic function of the innate immune system owing to mutations in genes encoding the five subunits of the nicotinamide adenine dinucleotide phosphatase (NADPH) oxidase enzyme complex. This review aimed to provide a comprehensive approach to the pathogens associated with chronic granulomatous disease (CGD) and its management. Patients with CGD, often children, have recurrent life-threatening infections and may develop infectious or inflammatory complications. The most common microorganisms observed in the patients with CGD are Staphylococcus aureus, Aspergillus spp., Candida spp., Nocardia spp., Burkholderia spp., Serratia spp., and Salmonella spp. Antibacterial prophylaxis with trimethoprim-sulfamethoxazole, antifungal prophylaxis usually with itraconazole, and interferon gamma immunotherapy have been successfully used in reducing infection in CGD. Haematopoietic stem cell transplantation (HCT) have been successfully proven to be the treatment of choice in patients with CGD.

The Keap1-Nrf2 signaling pathway regulates antioxidant defenses of Ctenopharyngodon idella induced by bacterial infection

Respiratory burst is a process involving rapid production of reactive oxygen species (ROS) for eliminating invading pathogens. However, excessive ROS production can be fatal to the host organism. The Keap1-Nrf2-ARE (Kelch-like ECH-associated protein 1 [Keap1]; Nuclear factor erythroid-derived 2-like 2 [Nrf2]; Antioxidant responsive element [ARE]) signaling pathway plays an important role in alleviating oxidative stress and preserving cellular homeostasis. However, the role of Keap1 during bacterial infection in fish remains unclear. In this study, we cloned and characterized the Keap1 gene of grass carp (CiKeap1) for the first time. CiKeap1 encodes a 593-amino acid protein of the Keap1b type. The tissue distribution analysis data revealed that the brain contains the highest transcription level of Keap1, followed by the heart and liver. The infection of Aeromonas hydrophila and Staphylococcus aureus obviously modulated the gene transcription and protein expression levels of Keap1, which suggested that the CiKeap1 participates in antibacterial immune responses. Furthermore, in vitro overexpression assays clarified the defensive and regular roles of CiKeap1 in maintaining host redox homeostasis in response to bacterial infection through the Keap1-Nrf2-ARE signaling pathway. In conclusion, the present results provide an expanded perspective on the role of Keap1 in teleost immunology that can guide healthy farming cultivation of grass carp.

Polymorphism in neutrophil cytosolic factor 4 (NCF4) of dairy cows had mastitis in previous lactations, and the relationship with the respiratory burst

Nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase), as a key factor in innate immunity, consists of several components, one of them is p40phox which is encoded by neutrophil cytosolic factor 4 (NCF4). Respiratory burst and reactive oxygen species (ROS) production are antimicrobial mechanisms associated with NADPH oxidase. This study evaluated the effects of g.18174 A > G and g.18270C > T single-nucleotide polymorphisms (SNP) in NCF4 on bovine mastitis and the respiratory burst capacity of neutrophils. SNPs of 160 dairy cattle were determined using a novel PCR-RFLP protocol by employing restriction enzymes, MboI and FokI. Also, the flow cytometry measured respiratory burst in 82 blood samples. Our results indicated that only g.18174 A > G SNP reduced the respiratory burst capacity. However, both SNPs were not significantly correlated with clinical mastitis. We concluded that g.18174 A > G decreases the function of NADPH oxidase. However, both SNPs were not significantly correlated with clinical mastitis.

Variant Type X91+ Chronic Granulomatous Disease: Clinical and Molecular Characterization in a Chinese Cohort

PURPOSE

We aimed to report the clinical and immunological characteristics of variant type X91⁺ chronic granulomatous disease (CGD) in a Chinese cohort.

METHODS

The clinical manifestations and immunological phenotypes of patients with X91⁺ CGD were collected. A dihydrorhodamine (DHR) analysis was performed to evaluate neutrophil function. Gp91^phox protein expression was determined using extracellular staining with the monoclonal antibody (mAb) 7D5 and flow cytometry.

RESULTS

Patients with X91⁺ CGD accounted for 8% (7/85) of all patients with CGD. The median age of onset in the seven patients with X91⁺ CGD was 4 months. Six patients received the BCG vaccine, and 50% (3/6) had probable BCG infections. Mycobacterium tuberculosis infection was prominent. The most common sites of infection were the lung (6/7), lymph nodes (5/7), and soft tissue (3/7). Two patients experienced recurrent oral ulcers. The stimulation index (SI) of the patients with X91⁺ CGD ranged widely from 1.9 to 67.3. The difference in the SI among the three groups of patients (X91⁺ CGD, X91^- CGD, and X91⁰ CGD) was statistically significant (P = 0.0071). The three groups showed no significant differences in onset age, diagnosis age, or severe infection frequency. CYBB mutations associated with X91⁺ CGD were commonly located in the second transmembrane or intracellular regions. Three novel X91⁺ CGD-related mutations (c.1462-2 A > T, c.1243C > T, and c.925G > A) were identified.

CONCLUSIONS

Variant type X91⁺ CGD may result in varied clinical manifestations. Moreover, the laboratory findings might indicate a moderate neutrophil SI. We should deepen our understanding of variant X91⁺ CGD to prevent missed diagnoses.

Role of Flow Cytometry in the Diagnosis of Inborn Errors of Immunity

Inborn errors of immunity (IEI) are a group of inherited heterogeneous disorders affecting the immune system characterized by increased susceptibility to infections, immune dysregulation, and lymphoproliferation. Flow cytometry (FCM) is a rapid and reliable technique for evaluation and enumeration of immune cells. It also helps in understanding the functional and signaling pathways of the immune system. Lymphocyte subset analysis is a simple and effective screening tool in suspected combined and humoral immunodeficiency patients. Qualitative phagocytic defects such as chronic granulomatous disease and leucocyte adhesion defect are easily diagnosed by FCM. Study of intracellular proteins (e.g., BTK, WASP, DOCK8), cytokine production, and signaling molecules (e.g., STAT3) by FCM is very useful but also quite challenging to establish. T and B lymphocyte interaction for normal class switching of B cells can be assessed and can help in diagnosis of combined variable immunodeficiency and hyperimmunoglobulin M syndrome. FCM is also used in posttransplant monitoring of IEI patients and also in prenatal diagnosis in suspected cases. It is also useful in validation of variants of uncertain significance obtained in exome sequencing. FCM results should always be interpreted with clinical history and, if needed, should be confirmed with molecular genetic studies before establishing the final diagnosis. Ensuring good sample quality and running parallel controls with patient samples will avoid the preanalytical and analytical errors. This review describes the applications of FCM in the diagnosis of various IEI.

Enhanced homology-directed repair for highly efficient gene editing in hematopoietic stem/progenitor cells

Lentivector gene therapy for X-linked chronic granulomatous disease (X-CGD) has proven to be a viable approach, but random vector integration and subnormal protein production from exogenous promoters in transduced cells remain concerning for long-term safety and efficacy. A previous genome editing-based approach using Streptococcus pyogenes Cas9 mRNA and an oligodeoxynucleotide donor to repair genetic mutations showed the capability to restore physiological protein expression but lacked sufficient efficiency in quiescent CD34+ hematopoietic cells for clinical translation. Here, we report that transient inhibition of p53-binding protein 1 (53BP1) significantly increased (2.3-fold) long-term homology-directed repair to achieve highly efficient (80% gp91phox+ cells compared with healthy donor control subjects) long-term correction of X-CGD CD34+ cells.

Small-Molecule Inhibitors of Reactive Oxygen Species Production

Reactive oxygen species (ROS) are involved in physiological cellular processes including differentiation, proliferation, and apoptosis by acting as signaling molecules or regulators of transcription factors. The maintenance of appropriate cellular ROS levels is termed redox homeostasis, a balance between their production and neutralization. High concentrations of ROS may contribute to severe pathological events including cancer, neurodegenerative, and cardiovascular diseases. In recent years, approaches to target the sources of ROS production directly in order to develop tool compounds or potential therapeutics have been explored. Herein, we briefly outline the major sources of cellular ROS production and comprehensively review the targeting of these by small-molecule inhibitors. We critically assess the value of ROS inhibitors with different mechanisms-of-action, including their potency, mode-of-action, known off-target effects, and clinical or preclinical status, while suggesting future avenues of research in the field.

Myeloid cell-derived HOCl is a paracrine effector that trans-inhibits IKK/NF-κB in melanoma cells and limits early tumor progression

The myeloperoxidase (MPO) system of myeloid-derived cells (MDCs) is central to cellular innate immunity. Upon MDC activation, MPO is secreted into phagosomes where it catalyzes the production of hypochlorous acid (HOCl), a potent chlorinating oxidant. Here, we demonstrated that the myeloid lineage-restricted MPO-HOCl system had antitumor effects in early melanoma growth in aged mice. Orthotopic melanomas grew more slowly in immunocompetent MPO^+/+ host mice compared to age-matched syngeneic MPO^-/- mice. Real-time intravital tumor imaging in vivo and in cell cocultures revealed a cell-cell proximity-dependent association between MDC-derived MPO enzyme activity and blockade of ligand-induced IκBα degradation in tumor cells. HOCl directly trans-inhibited IκB kinase (IKK) activity in tumor cells, thereby decreasing nuclear factor κB (NF-κB) transcriptional activation and inducing changes in the expression of genes involved in metabolic pathways, cell cycle progression, and DNA replication. By contrast, HOCl induced transcriptional changes in CD8⁺ T cells related to ion transport and the MAPK and PI3K-AKT signaling pathways that are associated with T cell activation. MPO increased the circulating concentrations of the myeloid cell-attracting cytokines CXCL1 and CXCL5, enhanced local infiltration by CD8⁺ cytotoxic T cells, and decreased tumor growth. Overall, these data reveal a role for MDC-derived HOCl as a small-molecule paracrine signaling factor that trans-inhibits IKK in melanoma tumor cells, mediating antitumor responses during early tumor progression.

Geographic Variability and Pathogen-Specific Considerations in the Diagnosis and Management of Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is a rare but serious primary immunodeficiency with varying prevalence and rates of X-linked and autosomal recessive disease worldwide. Functional defects in the phagocyte nicotinamide adenine dinucleotide phosphate oxidase complex predispose patients to a relatively narrow spectrum of bacterial and fungal infections that are sometimes fastidious and often difficult to identify. When evaluating and treating patients with CGD, it is important to consider their native country of birth, climate, and living situation, which may predispose them to types of infections that are atypical to your routine practice. In addition to recurrent and often severe infections, patients with CGD and X-linked female carriers are also susceptible to developing many non-infectious complications including tissue granuloma formation and autoimmunity. The DHR-123 oxidation assay is the gold standard for making the diagnosis and it along with genetic testing can help predict the severity and prognosis in patients with CGD. Disease management focuses on prophylaxis with antibacterial, antifungal, and immunomodulatory medications, prompt identification and treatment of acute infections, and prevention of secondary granulomatous complications. While hematopoietic stem-cell transplantation is the only widely available curative treatment for patients with CGD, recent advances in gene therapy may provide a safer, more direct alternative.

Acetaminophen Inhibits the Neutrophil Oxidative Burst: Implications for Diagnostic Testing

BACKGROUND

Chronic granulomatous disease is a primary immunodeficiency characterized by recurrent bacterial and fungal infections, granuloma formation, and inflammatory disease. Impaired neutrophil oxidative function is an essential diagnostic criterion. In vitro exposure of neutrophils to acetaminophen, a commonly used over-the-counter medication, has been associated with reduced neutrophil oxidative function. The clinical implications of acetaminophen intake for dihydrorhodamine (DHR) testing remain unknown.

OBJECTIVE

To evaluate the effect of in vivo administration of therapeutic doses of acetaminophen on DHR diagnostic testing.

METHODS

We performed DHR testing in 15 healthy adults before and after administering a single dose of acetaminophen. We retrospectively reviewed 195 DHR test results from hospitalized patients who had received acetaminophen, nonsteroidal anti-inflammatory drug, or corticosteroid before testing.

RESULTS

DHR testing result was abnormal in 100% (n = 15) of healthy adults 2 hours after acetaminophen intake. We identified 195 instances of DHR testing less than or equal to 72 hours after acetaminophen ingestion in hospitalized patients who did not have chronic granulomatous disease. DHR results were abnormal in 43 of 195 cases (22.1%). Frequency of false-positive testing was increased in patients who received acetaminophen within 24 hours of testing, and in patients who received more than 1 dose of acetaminophen. Nonsteroidal anti-inflammatory drug and corticosteroid intakes were not associated with abnormal DHR result.

CONCLUSIONS

Patients treated with acetaminophen have decreased neutrophil oxidative burst as measured by DHR testing. To avoid falsely abnormal testing for chronic granulomatous disease, patients should be advised to avoid acetaminophen for at least 24 hours before DHR testing.

Measurement of Respiratory Burst Products, Released or Retained, During Activation of Professional Phagocytes

Activation of professional phagocytes, potent microbial killers of our innate immune system, is associated with an increased cellular consumption of molecular oxygen (O₂). The O₂ molecules consumed are reduced by electrons delivered by a membrane localized NADPH-oxidase that initially generate one- and two electron reduced superoxide anions (O₂^-) and hydrogen peroxide (H₂O₂), respectively. These oxidants can then be processed into other highly reactive oxygen species (ROS) that can kill microbes, but that may also cause tissue destruction and drive other immune cells into apoptosis. The development of basic techniques to measure and quantify ROS generation by phagocytes is of great importance, and a large number of methods have been used for this purpose. A selection of methods (including chemiluminescence amplified by luminol or isoluminol, absorbance change following reduction of cytochrome c, and fluorescence increase upon oxidation of PHPA) are described in detail in this chapter with special emphasis on how to distinguish between ROS that are released extracellularly, and those that are retained within intracellular organelles. These techniques can be valuable tools in research spanning from basic phagocyte biology to diagnosis of diseases linked to the NADPH-oxidase and more clinically oriented research on innate immune mechanisms and inflammation.

Clinical and Molecular Features of Chronic Granulomatous Disease in Mainland China and a XL-CGD Female Infant Patient After Prenatal Diagnosis

PURPOSE

Chronic granulomatous disease (CGD) is the most common phagocyte defect disease. Here, we describe 114 CGD patients in our center and report a rare female infant with XL-CGD to provide a better understanding of diagnosis, treatment, and prenatal diagnosis of CGD.

METHOD

Patients were diagnosed by DHR-1,2,3 flow cytometry assays and gene analysis. X chromosome inactivation analysis and gp91^phox protein test were used for a female infant with XL-CGD.

RESULTS

XL-CGD accounts for the majority of cases in China and results in higher susceptibility to some infections than AR-CGD. The DHR assay can help diagnose CGD quickly, and atypical results should be combined with clinical manifestations, genetic analysis, and regular follow-up. For prenatal diagnosis, both gDNA and cDNA genotypes of amniotic fluid cells should be identified, and cord blood DHR assays should be performed to identify female XL-CGD patients.

Application of Flow Cytometry in Primary Immunodeficiencies: Experience From India

Primary immunodeficiency diseases (PID) are a clinically and immunologically heterogeneous group of disorders of immune system. Diagnosis of these disorders is often challenging and requires identification of underlying genetic defects, complemented by a comprehensive evaluation of immune system. Flow cytometry, with its advances in the last few decades, has emerged as an indispensable tool for enumeration as well as characterization of immune cells. Flow cytometric evaluation of the immune system not only provides clues to underlying genetic defects in certain PIDs and helps in functional validation of novel genetic defects, but is also useful in monitoring immune responses following specific therapies. India has witnessed significant progress in the field of flow cytometry as well as PID over last one decade. Currently, there are seven Federation of Primary Immunodeficiency Diseases (FPID) recognized centers across India, including two Indian Council of Medical research (ICMR) funded centers of excellence for diagnosis, and management of PIDs. These centers offer comprehensive care for PIDs including flow cytometry based evaluation. The key question which always remains is how one selects from the wide array of flow cytometry based tests available, and whether all these tests should be performed before or after the identification of genetic defects. This becomes crucial, especially when resources are limited and patients have to pay for the investigations. In this review, we will share some of our experiences based on evaluation of a large cohort of hemophagocytic lymphohistiocytosis, severe combined immunodeficiency, and chronic granulomatous disease, and the lessons learned for optimum use of this powerful technology for diagnosis of these disorders.

Tumor-Targeting Immune System Engagers (ISErs) Activate Human Neutrophils after Binding to Cancer Cells

Immune system engagers (ISErs) make up a new class of immunotherapeutics against cancer. They comprise two or more tumor-targeting peptides and an immune-stimulating effector peptide connected by inert polymer linkers. They are produced by solid phase peptide synthesis and share the specific targeting activities of antibodies (IgGs) but are much smaller in size and exploit a different immune-stimulating mechanism. Two ISErs (Y-9 and Y-59) that bind to the cancer cell markers integrin α3 and EphA2, respectively, are analyzed here with respect to their immune cell stimulation. We have previously shown that they activate formyl peptide receptors on myeloid immune cells and induce respiratory burst in neutrophils and myeloid chemotaxis in solution. It remained, however, unclear whether these molecules can stimulate immune cells while bound to tumor cells, an essential step in the hypothesized mode of action. Here, we demonstrate that ISEr Y-9 induced respiratory burst and caused a change in the shape of neutrophils when bound to the surface of protein A beads as a model of tumor cells. More importantly, tumor cell lines carrying receptor-bound Y-9 or Y-59 also activated neutrophils, evidenced by a significant change in shape. Interestingly, similar activation was induced by the supernatants of the cells incubated with ISEr, indicating that ISErs released from tumor cells, intact or degraded into fragments, significantly contributed to immune stimulation. These findings provide new evidence for the mode of action of ISErs, namely by targeting cancer cells and subsequently provoking an innate immune response against them.

Chitosan Acetylation Degree Influences the Physical Properties of Polysaccharide Nanoparticles: Implication for the Innate Immune Cells Response

The aim of the present contribution is twofold as it reports (i) on the role played by chitosan acetylation degree for the stability of nanoparticles (NPs) formed with hyaluronan and (ii) on the effect of the interaction of such NPs with immune cells. Chitosans with similar viscosity-average molecular weight, [Formula: see text], (i.e., 200 000) and different fractions of acetylated units ( F_A) together with low-molecular-weight hyaluronan were chosen for developing a select library of formulations via electrostatic complex coacervation. The resulting NPs were analyzed in terms of size, polydispersity, surface charge, and stability in physiological-mimicked media by dynamic light scattering. Only medium acetylated chitosan ( F_A = 0.16) guaranteed the stability of NPs. To explore the effect of NPs interaction with immune cells, the release of proinflammatory cytokines and the reactive oxygen species production by human macrophages and neutrophils, respectively, were evaluated. Strikingly, a structure-function relationship emerged, showing that NPs made of chitosans with F_A = 0.02, 0.25, 0.46, and 0.63 manifested a proinflammatory activity, linked to the instability of the system. Conversely, NPs made of chitosan with F_A = 0.16 neither modified the functional response of macrophages nor that of neutrophils. Of note, such NPs were found to possess additional properties potentially advantageous in applications such as delivery of therapeutics to target inflamed sites: (i) they are devoid of cytotoxic effects, (ii) they avoid engulfment during the early stage of interaction with macrophages, and (iii) they are muco-adhesive, thereby providing for site-specificity and long-residence effects.

Diagnostic Testing for Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is a rare genetic immunodeficiency associated with recurrent bacterial infections, granulomas, and increased mortality. It is characterized by the inability of phagocytes (neutrophils, monocytes, etc.) to generate reactive oxygen species (ROS), a major component of the microbicidal repertoire of phagocytes. Diagnosis of patients with CGD is commonly based on the assessment of ROS production by neutrophils. Multiple assays to assess ROS production are described-a flow cytometric dihydrorhodamine assay and a histochemical nitroblue tetrazolium assay, both of which can be used to visualize ROS production in individual cells, and two quantitative assays-O₂^˙- reduction of ferricytochrome c and a ROS-dependent, luminol-enhanced chemiluminescence assay that will quantitate the response of a population of cells. In addition, two approaches to identify the defective phox protein defect are described-standard immunoblotting and flow cytometry of neutrophils stained with phox-specific antibodies. When determining the status of a patient, several assays should be used to assess ROS production and identify the protein defect. The results of these assays should agree and can be used to develop a comprehensive package, which includes confirmation of a diagnosis of CGD, identification of the specific protein target for genetic sequencing, and an indication of the prognosis for the patient.

Reactive Oxygen Species: the Dual Role in Physiological and Pathological Conditions of the Human Body

Reactive oxygen species (ROS) are well-known for playing a dual role as destructive and constructive species. Indeed, ROS are engaged in many redox-governing activities of the cells for the preservation of cellular homeostasis. However, its overproduction has been reported to result in oxidative stress, which is considered as a deleterious process, and is involved in the damage of cell structures that causes various diseased states. This review provides a concise view on some of the current research published in this topic for an improved understanding of the key roles of ROS in diverse conditions of health and disease. Previous research demonstrated that ROS perform as potential signaling molecules to control several normal physiological functions at the cellular level. Additionally, there is a growing body of evidence supporting the role of ROS in various pathological states. The binary nature of ROS with their profitable and injurious characteristics indicates the complexities of their specific roles at a biological compartment and the difficulties in establishing convenient intervention procedures to treat ROS-related diseases.

Complex Coacervates between a Lactose-Modified Chitosan and Hyaluronic Acid as Radical-Scavenging Drug Carriers

Complex coacervation of two oppositely charged polysaccharides, namely a lactose-modified chitosan (CTL) and hyaluronan (HA), was investigated in this study. Coacervates of the two polysaccharides were prepared by drop-by-drop injection of HA into CTL. Transmittance and dynamic light scattering (DLS) measurements in combination with TEM analyses demonstrated the formation of spheroidal colloids in the nano-/microsize range showing good homogeneity. Strikingly, the presence of 150 mM supporting NaCl did not hamper the colloid formation. Stability studies on selected formulations demonstrated that HA/CTL coacervates were stable up to 3 weeks at 37 °C and behaved as pH-responsive colloids since transition from entangled to disentangled chains was attained for a proper pH range. The possibility of freeze-drying the coacervates for storage purposes and the ability of encapsulating selected payloads were investigated as well, for two values of the fraction of the lactitol side-chain substitution (F_L). Finally, biological tests using human neutrophils were undertaken at acidic pH value (pH = 6.0): under such experimental conditions, akin to those frequently occurring in the inflammatory microenvironment, coacervates scavenged reactive oxygen species (ROS) generated by these cells in basal conditions. Given the well documented bioactivity of CTL with respect to chitosan toward cartilage regeneration, these findings point to a possible application of HA/CTL-based colloids as scavenging and bioactive carriers for the delivery of therapeutic molecules at confined inflamed sites such as knee joints.

Considerations in the Diagnosis of Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is a rare primary immunodeficiency that is caused by defects in the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex. The disease presents in most patients initially with infection, especially of the lymph nodes, lung, liver, bone, and skin. Patients with CGD are susceptible to a narrow spectrum of pathogens, and Staphylococcus aureus, Burkholderia cepacia complex, Serratia marcescens, Nocardia species, and Aspergillus species are the most common organisms implicated in North America. Granuloma formation, most frequently in the gastrointestinal and genitourinary systems, is a common complication of CGD and can be seen even before diagnosis. An increased incidence of autoimmune disease has also been described in patients with CGD and X-linked female carriers. In patients who present with signs and symptoms consistent with CGD, a flow cytometric dihydrorhodamine neutrophil respiratory burst assay is a quick and cost-effective way to evaluate NADPH oxidase function. The purpose of this review is to highlight considerations for and challenges in the diagnosis of CGD.

Diagnostic Tools for Inborn Errors of Human Immunity (Primary Immunodeficiencies and Immune Dysregulatory Diseases)

PURPOSE OF REVIEW

The purpose of this review is to provide an overview of diagnostic testing in primary immunodeficiency and immune dysregulatory disorders (PIDDs), particularly focusing on flow cytometry and genetic techniques, utilizing specific examples of PIDDs.

RECENT FINDINGS

Flow cytometry remains a vital tool in the diagnosis and monitoring of immunological diseases. Its utility ranges from cellular analysis and specific protein quantitation to functional assays and signaling pathway analysis. Mass cytometry combines flow cytometry and mass spectrometry to dramatically increase the throughput of multivariate single-cell analysis. Next-generation sequencing in combination with other molecular techniques and processing algorithms has become more widely available and identified the diverse and heterogeneous genetic underpinnings of these disorders. As the spectrum of disease is further clarified by increasing immunological, genetic, and epigenetic knowledge, the careful application of these diagnostic tools and bioinformatics will assist not only in our understanding of these complex disorders, but also enable the implementation of personalized therapeutic approaches for disease management.

Elevated Mitochondrial Reactive Oxygen Species and Cellular Redox Imbalance in Human NADPH-Oxidase-Deficient Phagocytes

Chronic granulomatous disease (CGD) is caused by mutations in genes that encode the NADPH-oxidase and result in a failure of phagocytic cells to produce reactive oxygen species (ROS) via this enzyme system. Patients with CGD are highly susceptible to infections and often suffer from inflammatory disorders; the latter occurs in the absence of infection and correlates with the spontaneous production of inflammatory cytokines. This clinical feature suggests that NADPH-oxidase-derived ROS are not required for, or may even suppress, inflammatory processes. Experimental evidence, however, implies that ROS are in fact required for inflammatory cytokine production. By using a myeloid cell line devoid of a functional NADPH-oxidase and primary CGD cells, we analyzed intracellular oxidants, signs of oxidative stress, and inflammatory cytokine production. Herein, we demonstrate that phagocytes lacking a functional NADPH-oxidase, namely primary CGD phagocytes and a gp91^phox-deficient cell line, display elevated levels of ROS derived from mitochondria. Accordingly, these cells, despite lacking the major source of cellular ROS, display clear signs of oxidative stress, including an induced expression of antioxidants and altered oxidation of cell surface thiols. These observed changes in redox state were not due to abnormalities in mitochondrial mass or membrane integrity. Finally, we demonstrate that increased mitochondrial ROS enhanced phosphorylation of ERK1/2, and induced production of IL8, findings that correlate with previous observations of increased MAPK activation and inflammatory cytokine production in CGD cells. Our data show that elevated baseline levels of mitochondria-derived oxidants lead to the counter-intuitive observation that CGD phagocytes are under oxidative stress and have enhanced MAPK signaling, which may contribute to the elevated basal production of inflammatory cytokines and the sterile inflammatory manifestations in CGD.

Complete Myeloperoxidase Deficiency: Beware the "False-Positive" Dihydrorhodamine Oxidation

Myeloperoxidase deficiency is the most common inherited phagocyte disorder (1:2000) and causes an abnormal dihydrorhodamine oxidation test, which also is seen in chronic granulomatous disease. A patient with Candida meningitis and low dihydrorhodamine oxidation signal was diagnosed with chronic granulomatous disease but actually had compound heterozygous myeloperoxidase deficiency.

Role of Flow Cytometry in the Diagnosis of Chronic Granulomatous Disease: the Egyptian Experience

INTRODUCTION

Chronic granulomatous disease (CGD) is an inherited mutational defect in any of the NADPH oxidase complex, CYBB (gp91-phox), NCF1 (p47-phox), CYBA (p22-phox), NCF2 (p67-phox), or NCF4 (p40-phox) leading to inability of phagocytes to perform effective respiratory burst and thus diminished killing of bacteria and fungi. The identification of defective proteins aids in establishing a diagnosis prior to genetic analysis, which is rather labor-intensive, expensive, and time-consuming.

AIM

The present study aims at assessing the NADPH proteins by performing the intracellular staining with specific monoclonal antibodies and their assessment on flow cytometry. The use of flow cytometry is less laborious and faster to perform than western blot. It also confirms the diagnosis of CGD and detects the affected components allowing proper management of patients.

MATERIALS AND METHODS

Twenty-eight patients from 25 different kindred, clinically suspected as CGD were recruited in Egypt. Dihydrorhodamine test was performed to confirm the diagnosis of the patients. Intracellular staining of NADPH components using specific monoclonal antibodies was performed followed by flow cytometric analysis.

RESULTS

The present study revealed that the most common defective protein in our cohort is p22-phox, found in 13 patients (46.4 % of cases) followed by p47-phox in 8 patients (28.6 %), gp91-phox in 5 patients (17.9 %), and finally p67-phox in 2 patients (7.1 %).

CONCLUSION

In countries with limited resources and yet large number of CGD patients, the analysis of the defective proteins by flow cytometry is an optimum solution for confirming the diagnosis and is a step for targeted sequencing in families seeking prenatal diagnosis.

Flow Cytometry, a Versatile Tool for Diagnosis and Monitoring of Primary Immunodeficiencies

Genetic defects of the immune system are referred to as primary immunodeficiencies (PIDs). These immunodeficiencies are clinically and immunologically heterogeneous and, therefore, pose a challenge not only for the clinician but also for the diagnostic immunologist. There are several methodological tools available for evaluation and monitoring of patients with PIDs, and of these tools, flow cytometry has gained prominence, both for phenotyping and functional assays. Flow cytometry allows real-time analysis of cellular composition, cell signaling, and other relevant immunological pathways, providing an accessible tool for rapid diagnostic and prognostic assessment. This minireview provides an overview of the use of flow cytometry in disease-specific diagnosis of PIDs, in addition to other broader applications, which include immune phenotyping and cellular functional measurements.

Diagnostic and Treatment Options for Severe IBD in Female X-CGD Carriers with Non-random X-inactivation

BACKGROUND AND AIMS

X-linked chronic granulomatous disease [X-CGD] due to hemizygous mutations in CYBB is characterised by invasive bacterial and fungal infections and granulomatous inflammation. Inflammatory bowel disease [IBD] is an additional or isolated manifestation. Allogeneic haematopoietic stem cell transplantation [alloHSCT] is the standard curative treatment. X-CGD carriers are usually healthy but those with non-random X-chromosome inactivation [XCI] may develop infectious or autoinflammatory manifestations.

METHODS AND RESULTS

We report on two female patients with severe treatment-refractory Crohn-like IBD manifesting at age 23 and 8 years, respectively. NADPH-oxidase activity testing and molecular genetics proved X-CGD carrier status with non-random XCI. As in CGD, histopathology from colonic biopsies disclosed pigment-laden macrophages and reduced CD68(+) macrophages. Following submyelo-ablative conditioning, the younger patient was treated with alloHSCT at age 20 years. She came into remission within 3 months after transplantation and shows complete mucosal healing after 16 months off all medications.

CONCLUSIONS

We suggest that children and young adults with refractory IBD should mandatorily be tested for CGD. AlloHSCT should be considered as curative therapy in severely diseased female carriers of X-CGD with non-random XCI.

Flow cytometry in hematological nonmalignant disorders

Multiparameter flow cytometry (MFC) has become an integral part of the diagnosis and classification of hematological malignancies. However, several nonmalignant or premalignant disorders may benefit from this technology in hematology laboratories. This review provides information on the normal immunophenotypic characteristics of peripheral blood leukocyte subsets and their modifications in several clinical conditions. The usefulness of MFC and the specific markers that can be investigated in hyperlymphocytosis, infection, hypereosinophilia, paroxysmal nocturnal hemoglobinuria, and large granular lymphocyte disorders is described. Mention is also made of the developments of MFC for analyses of red blood cells or platelets.

Immune deficiency disorders involving neutrophils

This review addresses current thinking on the diagnosis, causation and management of common and rare primary disorders of granulocytes. The genetic basis of many of these disorders is now understood. Increased awareness is necessary to ensure that these disorders are identified promptly and treated appropriately.

Detection of the halogenating activity of heme peroxidases in leukocytes by aminophenyl fluorescein

The formation of hypochlorous and hypobromous acids by heme peroxidases is a key property of certain immune cells. These products are not only involved in defense against pathogenic microorganisms and in regulation of inflammatory processes, but contribute also to tissue damage in certain pathologies. After a short introduction about experimental approaches for the assessment of the halogenating activity in vitro and in cell suspensions, we are focusing on novel applications of fluorescent dye systems to detect the formation of hypochlorous acid (HOCl) in leukocytes. Special attention is directed to properties and applications of the non-fluorescent dye aminophenyl fluorescein that is converted by HOCl, HOBr, and other strong oxidants to fluorescein. This dye allows the detection of the halogenating activity in samples containing free myeloperoxidase and eosinophil peroxidase as well as in intact granulocytes using fluorescence spectroscopy and flow cytometry, respectively.

Laboratory diagnosis of primary immunodeficiencies

Primary immune deficiency disorders represent a highly heterogeneous group of disorders with an increased propensity to infections and other immune complications. A careful history to delineate the pattern of infectious organisms and other complications is important to guide the workup of these patients, but a focused laboratory evaluation is essential to the diagnosis of an underlying primary immunodeficiency. Initial workup of suspected immune deficiencies should include complete blood counts and serologic tests of immunoglobulin levels, vaccine titers, and complement levels, but these tests are often insufficient to make a diagnosis. Recent advancements in the understanding of the immune system have led to the development of novel immunologic assays to aid in the diagnosis of these disorders. Classically utilized to enumerate lymphocyte subsets, flow cytometric-based assays are increasingly utilized to test immune cell function (e.g., neutrophil oxidative burst, NK cytotoxicity), intracellular cytokine production (e.g., TH17 production), cellular signaling pathways (e.g., phosphor-STAT analysis), and protein expression (e.g., BTK, Foxp3). Genetic testing has similarly expanded greatly as more primary immune deficiencies are defined, and the use of mass sequencing technologies is leading to the identification of novel disorders. In order to utilize these complex assays in clinical care, one must have a firm understanding of the immunologic assay, how the results are interpreted, pitfalls in the assays, and how the test affects treatment decisions. This article will provide a systematic approach of the evaluation of a suspected primary immunodeficiency, as well as provide a comprehensive list of testing options and their results in the context of various disease processes.

Advances in the diagnosis and treatment of chronic granulomatous disease

PURPOSE OF REVIEW

Chronic granulomatous disease (CGD), characterized 50 years ago as a primary immunodeficiency disorder of phagocytic cells (resulting in failure to kill a defined spectrum of bacteria and fungi and in concomitant chronic granulomatous inflammation) now comprises five genetic defects impairing one of the five subunits of phagocyte NADPH oxidase (Phox). Phox normally generates reactive oxygen species (ROS) engaged in intracellular and extracellular host defence and resolving accompanying inflammatory processes. 'Fatal' granulomatous disease has now changed into a chronic inflammatory condition with a median survival of 35 years and is now of interest to both paediatricians and internists. Clinical vigilance and expert knowledge are needed for early recognition and tailored treatment of this relatively rare genetic disorder.

RECENT FINDINGS

Infections by unanticipated pathogens and noncirrhotic portal hypertension need to be recognized as new CGD manifestations. Adult-onset CGD too is increasingly observed even in the elderly. Conservative treatment of fungal infections needs close monitoring due to the spread of azole resistance following extensive use of azoles in agriculture. Curative haematopoietic stem cell transplantation (HSCT) in early childhood has expanded with impressive results following use of matched, unrelated or cord blood donors and of a reduced intensity conditioning (RIC) regimen. Gene therapy, however, still has major limitations, remaining experimental.

SUMMARY

CGD is more prevalent than initially believed with a birth prevalence of 1: 120 000. As patients are increasingly diagnosed around the world and grow older, further manifestations of CGD are expected. While fungal infections have lost some threat, therapeutic research focuses on two other important aims: pharmacologic cure of chronic inflammation and long-term cure of CGD by gene therapy.

Molecular diagnosis of chronic granulomatous disease

Patients with chronic granulomatous disease (CGD) suffer from recurrent, life-threatening bacterial and fungal infections of the skin, the airways, the lymph nodes, liver, brain and bones. Frequently found pathogens are Staphylococcus aureus, Aspergillus species, Klebsiella species, Burkholderia cepacia and Salmonella species. CGD is a rare (∼1:250 000 births) disease caused by mutations in any one of the five components of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in phagocytes. This enzyme generates superoxide and is essential for intracellular killing of pathogens by phagocytes. Molecular diagnosis of CGD involves measuring NADPH oxidase activity in phagocytes, measuring protein expression of NADPH oxidase components and mutation analysis of genes encoding these components. Residual oxidase activity is important to know for estimation of the clinical course and the chance of survival of the patient. Mutation analysis is mandatory for genetic counselling and prenatal diagnosis. This review summarizes the different assays available for the diagnosis of CGD, the precautions to be taken for correct measurements, the flow diagram to be followed, the assays for confirmation of the diagnosis and the determinations for carrier detection and prenatal diagnosis.

Diagnostic assays for myeloperoxidase and myeloperoxidase deficiency

Neutrophils (PMN) represent the dominant cell in the acute response to microbial infection and can contribute to some of the tissue damage that accompanies sterile inflammation. Effective antimicrobial activity in neutrophil phagosomes reflects the combined action of soluble agents in plasma with PMN-derived reactive oxygen species and granule proteins, including the azurophilic granule protein myeloperoxidase (MPO). The inhibition or the absence of the MPO-H2O2-halide system results in marked reduction in PMN killing of a variety of microbes, implicating its relative prominence in the hierarchy of PMN antimicrobial systems. Although the most profound clinical defects are manifested in patients lacking the capacity to generate reactive oxygen species, as seen in chronic granulomatous disease, an inherited deficiency of MPO can also increase the frequency or the severity of clinical infections.Like related peroxidases expressed in animals, MPO can catalyze both one- and two-electron oxidations, thereby mediating peroxidation and halogenation, respectively. The presence of each activity can be assessed in inflammatory fluids or by stimulated PMN. Furthermore, histochemical staining provides an assessment of functional MPO in tissue or within PMN, and immunoblotting of isolated PMN for MPO can provide additional insight into the molecular basis of the observed absence of functional enzyme.

Measurement of respiratory burst products, released or retained, during activation of professional phagocytes

Activation of professional phagocytes, potent microbial killers of our innate immune system, is associated with an increase in cellular consumption of molecular oxygen (O2). The consumed O2 is utilized by an NADPH-oxidase to generate highly reactive oxygen species (ROS) by a one electron reduction, initially generating superoxide anion (O2 (-)) that then dismutates to hydrogen peroxide (H2O2). The ROS are strongly bactericidal molecules but may also cause tissue destruction, and are capable of driving immune competent cells of both the innate and the adaptive immune systems into apoptosis. The development of basic techniques to measure/quantify ROS generation by phagocytes during activation of the respiratory burst is of great importance, and a large number of methods have been used for this purpose. A selection of methods, including chemiluminescence amplified by luminol or isoluminol, the absorbance change following reduction of cytochrome c, and the fluorescence increase upon oxidation of PHPA, are described in detail in this chapter with special emphasis on how to distinguish between ROS that are released extracellularly, and those that are retained within intracellular organelles. These techniques can be valuable tools in research spanning from basic phagocyte biology to more clinically oriented research on innate immune mechanisms and inflammation.

Diagnostic assays for chronic granulomatous disease and other neutrophil disorders

Inasmuch as neutrophils are the primary cellular defense against bacterial and fungal infections, disorders that affect these white cells typically predispose individuals to severe and recurrent infections. Therefore, diagnosis of such disorders is an important first step in directing long-term treatment/care for the patient. Herein, we describe methods to identify chronic granulomatous disease, leukocyte adhesion deficiency, and neutropenia. The assays are relatively simple to perform and cost effective and can be performed with equipment available in most laboratories.

Defects in neutrophil granule mobilization and bactericidal activity in familial hemophagocytic lymphohistiocytosis type 5 (FHL-5) syndrome caused by STXBP2/Munc18-2 mutations

Neutrophils of patients with FHL-5 with Munc18-2/STXBP2 mutations have impaired granule fusion and bacterial killing.

Detection of superoxide anion and hydrogen peroxide production by cellular NADPH oxidases

BACKGROUND

The recent recognition that isoforms of the cellular NADPH-dependent oxidases, collectively known as the NOX protein family, participate in a wide range of physiologic and pathophysiologic processes in both the animal and plant kingdoms has stimulated interest in the identification, localization, and quantitation of their products in biological settings. Although several tools for measuring oxidants released extracellularly are available, the specificity and selectivity of the methods for reliable analysis of intracellular oxidants have not matched the enthusiasm for studying NOX proteins.

SCOPE OF REVIEW

Focusing exclusively on superoxide anion and hydrogen peroxide produced by NOX proteins, this review describes the ideal probe for analysis of O2(-) and H2O2 generated extracellularly and intracellularly by NOX proteins. An overview of the components, organization, and topology of NOX proteins provides a rationale for applying specific probes for use and a context in which to interpret results and thereby construct plausible models linking NOX-derived oxidants to biological responses. The merits and shortcomings of methods currently in use to assess NOX activity are highlighted, and those assays that provide quantitation of superoxide or H2O2 are contrasted with those intended to examine spatial and temporal aspects of NOX activity.

MAJOR CONCLUSIONS

Although interest in measuring the extracellular and intracellular products of the NOX protein family is great, robust analytical probes are limited.

GENERAL SIGNIFICANCE

The widespread involvement of NOX proteins in many biological processes requires rigorous approaches to the detection, localization, and quantitation of the oxidants produced. This article is part of a Special Issue entitled Current methods to study reactive oxygen species - pros and cons and biophysics of membrane proteins. Guest Editor: Christine Winterbourn.

Intracellular shunting of O2(-) contributes to charge compensation and preservation of neutrophil respiratory burst in the absence of voltage-gated proton channel activity

Proton efflux via voltage-gated proton channels (Hv1) is considered to mediate the charge compensation necessary to preserve NADPH oxidase activity during the respiratory burst. Using the Hv1 inhibitor Zn²⁺, we found that the PMA-induced respiratory burst of human neutrophils is inhibited when assessed as extracellular production of O₂⁻ and H₂O₂, in accordance with literature studies, but, surprisingly, unaffected when measured as oxygen consumption or total (extracellular plus intracellular) H₂O₂ production. Furthermore, we show that inhibiting Hv1 with Zn²⁺ results in an increased production of intracellular ROS. Similar results, i.e. decreased extracellular and increased intracellular ROS production, were obtained using a human granulocyte-like cell line with severely impaired Hv1 expression. Acidic extracellular pH, which dampens proton efflux, also augmented intracellular production of H₂O₂. Zinc caused an increase in the rate but not in the extent of depolarization and cytosolic acidification indicating that mechanisms other than proton efflux take part in charge compensation.

Our results suggest a hitherto unpredicted mechanism of charge compensation whereby, in the absence of proton efflux, part of O₂⁻ generated within gp91^phox in the plasma membrane is shunted intracellularly down electrochemical gradient to dampen excessive depolarization. This would preserve NADPH oxidase activity under conditions such as the inflammatory exudate in which the acidic pH hinders charge compensation by proton efflux.

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Neutrophils’ respiratory burst is not inhibited by the H⁺ channel inhibitor Zn²⁺.

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Intracellular production of O₂⁻ and H₂O₂ is increased in the presence of Zn²⁺.

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Intracellular H₂O₂ production is increased in H⁺ channels knock-down cells.

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Zn²⁺ increases the rate but not the extent of depolarization and pH_i decrease.

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Intracellular shunting of O₂⁻ contributes to charge compensation in neutrophils.

Mitochondrial dysfunction and the inflammatory response

Inflammation has been linked to multiple degenerative and acute diseases as well as the aging process. Moreover, mitochondrial alterations play a central role in these processes. Mitochondria have an important role in pro-inflammatory signaling; similarly, pro-inflammatory mediators may also alter mitochondrial function. Both of these processes increase mitochondrial oxidative stress, promoting a vicious inflammatory cycle. Additionally, damage-associated molecular patterns derived from mitochondria could contribute to inflammasome formation and caspase-1 activation, while alterations in mitochondrial autophagy may cause inflammation. Strategies aimed at controlling excessive oxidative stress within mitochondria may represent both preventive and therapeutic interventions in inflammation.

Reduced atherosclerotic burden in subjects with genetically determined low oxidative stress

OBJECTIVE

NADPH oxidase, one of the most important enzymes producing reactive oxidant species, is suggested to play a role in experimental atherosclerosis, but its role in human atherosclerosis is still unclear. We hypothesized that a reduced activity of NADPH oxidase might be linked to a reduced atherosclerotic burden.

METHODS AND RESULTS

Thirty-one women carriers of hereditary deficiency of NOX2, the catalytic subunit of NADPH oxidase, were matched for sex and age with 31 controls and 31 obese women. Flow-mediated dilation and intima-media thickness, 2 surrogate markers of atherosclerosis, serum activity of NOX2, urinary isoprostanes, serum levels of nitrite/nitrate, and platelet production of isoprostanes and nitrite/nitrate were determined. Compared with controls (5.7±3.0% and 0.60±0.11 mm), carriers of NOX2 deficiency had higher flow-mediated dilation (9.2±5.0%; P<0.001) and lower intima-media thickness (0.50±0.11 mm; P=0.002), whereas obese women had lower flow-mediated dilation (3.2±2.1%; P=0.007) and higher intima-media thickness (0.71±0.15 mm; P<0.001). Compared with controls, carriers of NOX2 deficiency had lower urinary isoprostanes (132.6±87.3 versus 82.3±46.0 pg/mg creatinine; P=0.007) and serum NOX2 activity (24.9±19.3 versus 12.8±11.9 pg/mL; P=0.004) and higher serum nitrite/nitrate (23.8±7.6 versus 30.5±6.3 µmol/L; P<0.001), whereas obese women had higher urinary isoprostanes (132.6±87.3 versus 182.2±84.6 pg/mg creatinine; P=0.008) and serum NOX2 activity (24.9±19.3 versus 36.1±18.6 pg/mL; P=0.008) and lower serum nitrite/nitrate (23.8±7.6 versus 12.6±4.2 µmol/L; P<0.001). Flow-mediated dilation correlated with intima-media thickness (r=-0.433; P<0.001), serum NOX2 activity (r=-325; P<0.001), and urinary isoprostanes (r=-0.314; P=0.002). Ex vivo study showed that, compared with controls, platelets from carriers of NOX2 deficiency had lower isoprostanes (P<0.001) and higher nitrite/nitrate (P<0.001), whereas platelets from obese women had higher isoprostanes (P<0.001) and lower nitrite/nitrate (P=0.013).

CONCLUSIONS

The study shows reduced atherosclerotic burden in carriers of NOX2 deficiency, suggesting that oxidative stress generated by this enzymatic pathway is implicated in human atherosclerosis.

Chronic granulomatous disease

Chronic granulomatous disease (CGD) is a paradigm for nonlymphoid primary immune defects, and has guided elucidation of oxygen metabolism in the phagocyte, vasculature, and brain. It has been in the forefront of the development of antimicrobial prophylaxis before the advent of advanced HIV and before its routine use in neutropenia. It has been an attractive target for gene therapy and bone marrow transplantation for nonmalignant diseases. Therefore, CGD is worthy of attention for its historical interest and because it is a disease for which expert management is imperative.

The effect of storage on whole blood chemiluminescence measurement of equine neutrophils

The aim of this study was to determine the effect of duration and temperature of sample storage on whole blood chemiluminescence measurement results. Venous blood from 18 clinically healthy Polish half-bred horses aged 4 to 11 years were used in the study. Luminol dependent chemiluminescence (CL) was used to measure neutrophil oxygen metabolism in whole blood. Blood samples were examined for spontaneous CL and stimulated by a surface receptor stimulus as well as extra-receptor stimulus. The assay was performed in two parallel experimental sets with samples stored at 4 and 22 °C, respectively. Whole blood CL was estimated at 2, 6, 24, 48, 72, 96 and 120 h after collection. The study demonstrated that temperature and duration of sample storage are factors that determine the quality of CL measurements of whole blood in horses. The study concluded that samples should be stored at 4 °C and the assay should be performed as early as possible. It was also shown that the viability period of horse blood for CL assays is relatively long. Material stored at room temperature for 24 h and even up to 48 h at 4 °C did not show any significant decrease in spontaneous or stimulated chemiluminescence.

P67-phox (NCF2) lacking exons 11 and 12 is functionally active and leads to an extremely late diagnosis of chronic granulomatous disease (CGD)

Two brothers in their fifties presented with a medical history of suspected fungal allergy, allergic bronchopulmonary aspergillosis, alveolitis, and invasive aspergillosis and pulmonary fistula, respectively. Eventually, after a delay of 50 years, chronic granulomatous disease (CGD) was diagnosed in the index patient. We found a new splice mutation in the NCF2 (p67-phox) gene, c.1000+2T→G, that led to several splice products one of which lacked exons 11 and 12. This deletion was in frame and allowed for remarkable residual NADPH oxidase activity as determined by transduction experiments using a retroviral vector. We conclude that p67-phox which lacks the 34 amino acids encoded by the two exons can still exert considerable functional activity. This activity can partially explain the long-term survival of the patients without adequate diagnosis and treatment, but could not prevent progressing lung damage.

Chronic granulomatous disease

Chronic granulomatous disease (CGD) is a rare primary immunodeficiency due to an abnormal function of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase; NADPH oxidase is a key enzyme for the cellular "respiratory burst", the cellular process that converts molecular oxygen to the oxygen free-radical superoxide. As a consequence of NADPH oxidase defect, CGD patients suffer from recurrent life-threatening infections and from exceeding inflammatory responses leading to granulomas. This article analyzes clinical aspects of CGD. Furthermore, using the CGD model, we focused on the future perspective to reduce atherosclerosis and its complications.

Myeloperoxidase is required for neutrophil extracellular trap formation: implications for innate immunity

The granule enzyme myeloperoxidase (MPO) plays an important role in neutrophil antimicrobial responses. However, the severity of immunodeficiency in patients carrying mutations in MPO is variable. Serious microbial infections, especially with Candida species, have been observed in a subset of completely MPO-deficient patients. Here we show that neutrophils from donors who are completely deficient in MPO fail to form neutrophil extracellular traps (NETs), indicating that MPO is required for NET formation. In contrast, neutrophils from partially MPO-deficient donors make NETs, and pharmacological inhibition of MPO only delays and reduces NET formation. Extracellular products of MPO do not rescue NET formation, suggesting that MPO acts cell-autonomously. Finally, NET-dependent inhibition of Candida albicans growth is compromised in MPO-deficient neutrophils. The inability to form NETs may contribute in part to the host defense defects observed in completely MPO-deficient individuals.

Residual NADPH oxidase and survival in chronic granulomatous disease

BACKGROUND

Failure to generate phagocyte-derived superoxide and related reactive oxygen intermediates (ROIs) is the major defect in chronic granulomatous disease, causing recurrent infections and granulomatous complications. Chronic granulomatous disease is caused by missense, nonsense, frameshift, splice, or deletion mutations in the genes for p22(phox), p40(phox), p47(phox), p67(phox) (autosomal chronic granulomatous disease), or gp91(phox) (X-linked chronic granulomatous disease), which result in variable production of neutrophil-derived ROIs. We hypothesized that residual ROI production might be linked to survival in patients with chronic granulomatous disease.

METHODS

We assessed the risks of illness and death among 287 patients with chronic granulomatous disease from 244 kindreds. Residual ROI production was measured with the use of superoxide-dependent ferricytochrome c reduction and flow cytometry with dihydrorhodamine oxidation assays. Expression of NADPH oxidase component protein was detected by means of immunoblotting, and the affected genes were sequenced to identify causal mutations.

RESULTS

Survival of patients with chronic granulomatous disease was strongly associated with residual ROI production as a continuous variable, independently of the specific gene affected. Patients with mutations in p47(phox) and most missense mutations in gp91(phox) (with the exception of missense mutations in the nucleotide-binding and heme-binding domains) had more residual ROI production than patients with nonsense, frameshift, splice, or deletion mutations in gp91(phox). After adolescence, mortality curves diverged according to the extent of residual ROI production.

CONCLUSIONS

Patients with chronic granulomatous disease and modest residual production of ROI have significantly less severe illness and a greater likelihood of long-term survival than patients with little residual ROI production. The production of residual ROI is predicted by the specific NADPH oxidase mutation, regardless of the specific gene affected, and it is a predictor of survival in patients with chronic granulomatous disease. (Funded by the National Institutes of Health.).

Intracellular generation of superoxide by the phagocyte NADPH oxidase: how, where, and what for?

Professional phagocytes increase their consumption of molecular oxygen during the phagocytosis of microbes or when encountering a variety of nonparticulate stimuli. In these circumstances, oxygen is reduced by the phagocyte NADPH oxidase, and reactive oxygen species (ROS), which are important for the microbicidal activity of the cells, are generated. The structure and function of the NADPH oxidase have been resolved in part by studying cells from patients with chronic granulomatous disease (CGD), a condition characterized by the inability of phagocytes to assemble a functional NADPH oxidase and thus to produce ROS. As a result, patients with CGD have a predisposition to infections as well as a variety of inflammatory symptoms. A long-standing paradigm has been that NADPH oxidase assembly occurs exclusively in the plasma membrane or invaginations thereof (phagosomes). A growing body of evidence points to the possibility that phagocytes are capable of NADPH oxidase assembly in nonphagosomal intracellular membranes, resulting in ROS generation within intracellular organelles also in the absence of phagocytosis. The exact nature of these ROS-producing organelles is yet to be determined, but granules are prime suspects. Recent clinical findings indicate that the generation of intracellular ROS by NADPH oxidase activation is important for limiting inflammatory reactions and that intracellular and extracellular ROS production are regulated differently. Here we discuss the accumulating knowledge of intracellular ROS production in phagocytes and speculate on the precise role of these oxidants in regulating the inflammatory process.