A variant of chronic granulomatous disease: deficient oxidative metabolism due to a low-affinity NADPH oxidase

Voltage-gated proton channels: molecular biology, physiology, and pathophysiology of the H(V) family

Voltage-gated proton channels (H(V)) are unique, in part because the ion they conduct is unique. H(V) channels are perfectly selective for protons and have a very small unitary conductance, both arguably manifestations of the extremely low H(+) concentration in physiological solutions. They open with membrane depolarization, but their voltage dependence is strongly regulated by the pH gradient across the membrane (ΔpH), with the result that in most species they normally conduct only outward current. The H(V) channel protein is strikingly similar to the voltage-sensing domain (VSD, the first four membrane-spanning segments) of voltage-gated K(+) and Na(+) channels. In higher species, H(V) channels exist as dimers in which each protomer has its own conduction pathway, yet gating is cooperative. H(V) channels are phylogenetically diverse, distributed from humans to unicellular marine life, and perhaps even plants. Correspondingly, H(V) functions vary widely as well, from promoting calcification in coccolithophores and triggering bioluminescent flashes in dinoflagellates to facilitating killing bacteria, airway pH regulation, basophil histamine release, sperm maturation, and B lymphocyte responses in humans. Recent evidence that hH(V)1 may exacerbate breast cancer metastasis and cerebral damage from ischemic stroke highlights the rapidly expanding recognition of the clinical importance of hH(V)1.

pH regulation and beyond: unanticipated functions for the voltage-gated proton channel, HVCN1

Electrophysiological studies have implicated voltage-gated proton channels in several specific cellular contexts. In neutrophils, they mediate charge compensation that is associated with the oxidative burst of phagocytosis. Molecular characterization of the hydrogen voltage-gated channel 1 (HVCN1) has enabled identification of unanticipated and diverse functions: HVCN1 not only modulates signaling from the B-cell receptor following B-cell activation and histamine release from basophils, but also mediates pH-dependent activation of spermatozoa, as well as acid secretion by tracheal epithelium. The importance of HVCN1 in pH regulation during phagocytosis was established by surprising evidence that indicated its first-responder role. In this review, we discuss recent findings from a functional perspective, and the potential of HVCN1 as a therapeutic target for autoimmune and other diseases.

Family clusters of variant X-linked chronic granulomatous disease

Chronic granulomatous disease (CGD) is a rare inherited immunodeficiency disorder. The clinical presentation is varied depending on the degree of involvement of the NADPH oxidase system responsible for the oxidative burst of neutrophils. We present 3 cases of variant X-linked CGD in an effort to introduce the disease and highlight the importance and limitations of CGD screening. The variant X-linked form of CGD results in a less severe phenotype and frequently presents later in life. Variant X-linked CGD is difficult to diagnose, but is becoming more readily recognized based on improved testing methods. A high index of suspicion in the setting of unusual infections such as Burkholderia cepacia pneumonia is essential to make the diagnosis. Family screening can lead to early intervention, prophylaxis, and appropriate genetic counseling.

Chronic Granulomatous Disease; fundamental stages in our understanding of CGD

It has been 50 years since chronic granulomatous disease was first reported as a disease which fatally affected the ability of children to survive infections. Various milestone discoveries from the insufficient ability of patients' leucocytes to destroy microbial particles to the underlying genetic predispositions through which the disease is inherited have had important consequences. Longterm antibiotic prophylaxis has helped to fight infections associated with chronic granulomatous disease while the steady progress in bone marrow transplantation and the prospect of gene therapy are hailed as long awaited permanent treatment options. This review unearths the important findings by scientists that have led to our current understanding of the disease.

How neutrophils kill microbes

Neutrophils provide the first line of defense of the innate immune system by phagocytosing, killing, and digesting bacteria and fungi. Killing was previously believed to be accomplished by oxygen free radicals and other reactive oxygen species generated by the NADPH oxidase, and by oxidized halides produced by myeloperoxidase. We now know this is incorrect. The oxidase pumps electrons into the phagocytic vacuole, thereby inducing a charge across the membrane that must be compensated. The movement of compensating ions produces conditions in the vacuole conducive to microbial killing and digestion by enzymes released into the vacuole from the cytoplasmic granules.

The NADPH oxidase of professional phagocytes--prototype of the NOX electron transport chain systems

The NADPH oxidase is an electron transport chain in "professional" phagocytic cells that transfers electrons from NADPH in the cytoplasm, across the wall of the phagocytic vacuole, to form superoxide. The electron transporting flavocytochrome b is activated by the integrated function of four cytoplasmic proteins. The antimicrobial function of this system involves pumping K+ into the vacuole through BKCa channels, the effect of which is to elevate the vacuolar pH and activate neutral proteases. A number of homologous systems have been discovered in plants and lower animals as well as in man. Their function remains to be established.

In vivo production of hydroxyl radical by Enterococcus faecalis colonizing the intestinal tract using aromatic hydroxylation

Enterococcus faecalis is an intestinal commensal that produces extracellular superoxide (O(2)(*-)) through autoxidation of membrane-associated demethylmenaquinone. To assess free radical production by E. faecalis in vivo, intestinal tracts of rats were colonized using wild-type E. faecalis or a mutant strain with attenuated O(2)(*-) production. Ex vivo electron paramagnetic resonance spin trapping study of colonic contents (mean +/- SD) showed 1.4 +/- 1.5 and 0.094 +/- 0.24 microM 5,5-dimethyl-1-pyrroline-N-oxide-hydroxyl radical adduct/gm stool for rats colonized with wild-type and mutant strains, respectively (p = .002). In vivo hydroxyl radical production was further assayed by aromatic hydroxylation using phenyl N-tert-butylnitrone (PBN) and D-phenylalanine. Hydroxylated PBN and D-phenylalanine products were recovered from stool (microM/gm colonic contents/10(9) colony forming units) and urine (microM/h/ml), respectively, and quantified using electrochemical detection. Hydroxylated (OH) PBNs and isomeric tyrosines (hydroxylated phenylalanine) were significantly increased (mean +/- SD) for rats colonized with wild-type E. faecalis (2-OH PBN, 63 +/- 58; 3-OH PBN, 63 +/- 84; ortho-tyrosine, 31 +/- 27; meta-tyrosine, 17 +/- 14) compared to the mutant strain (2-OH PBN, 2.5 +/- 7.3 (p < .001); 3-OH PBN, 3.9 +/- 12.3 (p = .01); ortho-tyrosine, 1.9 +/- 6.0 (p < .001); meta-tyrosine, 1.5 +/- 3.4 (p = .03)). Similar differences were observed following in vitro incubations of these bacteria with aromatic targets. These results confirm in vivo production of hydroxyl radical by E. faecalis colonizing the intestine, and indicate this bacterium may be a potent source of oxidative stress on the intestinal epithelium.

Variable correction of host defense following gene transfer and bone marrow transplantation in murine X-linked chronic granulomatous disease

Chronic granulomatous disease (CGD) is an inherited immunodeficiency in which the absence of the phagocyte superoxide-generating nicotinamide adenine dinucleotide phosphate (NADPH) oxidase results in recurrent bacterial and fungal infections. A murine model of X-linked CGD (X-CGD) was used to explore variables influencing reconstitution of host defense following bone marrow transplantation and retroviral-mediated gene transfer. The outcomes of experimental infection with Aspergillus fumigatus, Staphylococcus aureus, or Burkholderia cepacia were compared in wild-type, X-CGD mice, and transplanted X-CGD mice that were chimeric for either wild-type neutrophils or neutrophils with partial correction of NADPH oxidase activity after retroviral-mediated gene transfer. Host defense to these pathogens was improved in X-CGD mice even with correction of a limited number of neutrophils. However, intact protection against bacterial pathogens required relatively greater numbers of oxidant-generating phagocytes compared to protection against A fumigatus. The host response also appeared to be influenced by the relative level of cellular NADPH oxidase activity, particularly for A fumigatus. These results may have implications for developing effective approaches for gene therapy of CGD. (Blood. 2001;97:3738-3745)

Interferon-gamma improves splicing efficiency of CYBB gene transcripts in an interferon-responsive variant of chronic granulomatous disease due to a splice site consensus region mutation

X-linked chronic granulomatous disease (CGD) derives from defects in the CYBB gene, which encodes the gp91-phox component of NADPH oxidase. We studied the molecular basis of the disease in a kindred with variant CGD, due to a single base substitution at the sixth position of CYBB first intron. The patients' phagocytes have been shown previously to greatly increase superoxide release in response to interferon-gamma (IFN-γ) in vitro and in vivo. We examined CYBB gene expression in an Epstein-Barr virus (EBV)-transformed B-cell line from 1 patient in this kindred. These cells showed markedly decreased levels of CYBB transcripts in total RNA (5% of normal) and nuclear RNA (1.4% of normal), despite equal CYBB transcription rates in the CGD and control cells. Incubation with IFN-γ produced a 3-fold increase in CYBBtotal messenger RNA (mRNA) levels in the patient's cells, and decreased nuclear transcripts to undetectable levels. Reverse transcriptase–polymerase chain reaction analysis of RNA splicing revealed a preponderance of unspliced CYBB transcripts in the patient's nuclear RNA. In vitro incubation with IFN-γ increased by 40% the ratio of spliced relative to unspliced CYBB mRNA in nuclei from the CGD B-cell line. Total RNA harvested from the same patient's monocytes, on and off therapy with IFN-γ, showed a similar improvement in splicing. We conclude that IFN-γ partially corrects a nuclear processing defect due to the intronic mutation in theCYBB gene in this kindred, most likely by augmentation of nuclear export of normal transcripts, and improvement in the fidelity of splicing at the first intron.

Interferon-gamma improves splicing efficiency of CYBB gene transcripts in an interferon-responsive variant of chronic granulomatous disease due to a splice site consensus region mutation

X-linked chronic granulomatous disease (CGD) derives from defects in the CYBB gene, which encodes the gp91-phox component of NADPH oxidase. We studied the molecular basis of the disease in a kindred with variant CGD, due to a single base substitution at the sixth position of CYBB first intron. The patients' phagocytes have been shown previously to greatly increase superoxide release in response to interferon-gamma (IFN-γ) in vitro and in vivo. We examined CYBB gene expression in an Epstein-Barr virus (EBV)-transformed B-cell line from 1 patient in this kindred. These cells showed markedly decreased levels of CYBB transcripts in total RNA (5% of normal) and nuclear RNA (1.4% of normal), despite equal CYBB transcription rates in the CGD and control cells. Incubation with IFN-γ produced a 3-fold increase in CYBBtotal messenger RNA (mRNA) levels in the patient's cells, and decreased nuclear transcripts to undetectable levels. Reverse transcriptase–polymerase chain reaction analysis of RNA splicing revealed a preponderance of unspliced CYBB transcripts in the patient's nuclear RNA. In vitro incubation with IFN-γ increased by 40% the ratio of spliced relative to unspliced CYBB mRNA in nuclei from the CGD B-cell line. Total RNA harvested from the same patient's monocytes, on and off therapy with IFN-γ, showed a similar improvement in splicing. We conclude that IFN-γ partially corrects a nuclear processing defect due to the intronic mutation in theCYBB gene in this kindred, most likely by augmentation of nuclear export of normal transcripts, and improvement in the fidelity of splicing at the first intron.

Genetic, biochemical, and clinical features of chronic granulomatous disease

The reduced nicotinamide dinucleotide phosphate (NADPH) oxidase complex allows phagocytes to rapidly convert O2 to superoxide anion which then generates other antimicrobial reactive oxygen intermediates, such as H2O2, hydroxyl anion, and peroxynitrite anion. Chronic granulomatous disease (CGD) results from a defect in any of the 4 subunits of the NADPH oxidase and is characterized by recurrent life-threatening bacterial and fungal infections and abnormal tissue granuloma formation. Activation of the NADPH oxidase requires translocation of the cytosolic subunits p47phox (phagocyte oxidase), p67phox, and the low molecular weight GT-Pase Rac, to the membrane-bound flavocytochrome, a heterodimer composed of the heavy chain gp91phox and the light chain p22phox. This complex transfers electrons from NADPH on the cytoplasmic side to O2 on the vacuolar or extracellular side, thereby generating superoxide anion. Activation of the NADPH oxidase requires complex rearrangements between the protein subunits, which are in part mediated by noncovalent binding between src-homology 3 domains (SH3 domains) and proline-rich motifs. Outpatient management of CGD patients relies on the use of prophylactic antibiotics and interferon-gamma. When infection is suspected, aggressive effort to obtain culture material is required. Treatment of infections involves prolonged use of systemic antibiotics, surgical debridement when feasible, and, in severe infections, use of granulocyte transfusions. Mouse knockout models of CGD have been created in which to examine aspects of pathophysiology and therapy. Gene therapy and bone marrow transplantation trials in CGD patients are ongoing and show great promise.

Identification of (CA/GT)n polymorphisms within the X-linked chronic granulomatous disease (X-CGD) gene: utility for prenatal diagnosis

PURPOSE

The majority of known female carriers of X-linked chronic granulomatous disease (X-CGD), a deficiency of the gp91-phox (phagocyte oxidase) subunit and the most common genetic subtype of CGD, are not informative for the linked restriction fragment length polymorphisms (RFLPs) described to date. The isolation and characterization of two polymorphic (CA/GT)n repeats that lie within the X-CGD gene are reported, which are a useful linked marker for prenatal diagnosis.

PATIENTS AND METHODS

cDNA for gp91-phox was used to probe a genomic library. Genomic clones were isolated and screened for (CA/GT)n repeats. The repeats were isolated and sequences surrounding the repeats were determined. Oligonucleotide primer pairs surrounding the repeats were chosen to facilitate polymerase chain reaction (PCR) across the repeat.

RESULTS

Analysis of DNA derived from over 100 individuals shows both markers to be highly polymorphic with a resultant high proportion of heterozygosity in females. Several kindreds affected by X-CGD were studied and the (CA/GT)n length polymorphisms were shown to segregate with the clinical syndrome or biochemical carrier status. The technique was prospectively applied to several kindreds containing a carrier mother and an affected child. In a case where a male fetus was shown to carry the unaffected allele, the pregnancy was carried to term and the child was not affected.

CONCLUSIONS

This approach is highly informative in a multiple allele system, can provide a technical analysis in just hours, requires only a ng of DNA, and permits the transport of diagnostic samples. Therefore, this method can be used early in pregnancy on a chorionic villus biopsy sample for prenatal diagnosis.

The cytosolic subunit p67phox contains an NADPH-binding site that participates in catalysis by the leukocyte NADPH oxidase

The NADPH-dependent respiratory burst oxidase of human neutrophils catalyzes the reduction of oxygen to superoxide using NADPH as the electron donor and is essential for normal host defenses. To gain insight into the function of the various oxidase subunits that are required for the full expression of catalytic activity, we studied the interactions between the 2',3'-dialdehyde derivative of NADPH (NADPH dialdehyde) and neutrophil cytosol. NADPH dialdehyde treatment of cytosol resulted in the loss of the ability of the cytosol to participate in cell-free oxidase activation; this inactivation was blocked by NADPH but not by NAD, NADP, or GTP. Partial purification of neutrophil cytosol yielded a single peak which could restore the activity lost in cytosol treated with NADPH dialdehyde. This peak contained p67phox but not p47phox or Rac2. Purified recombinant p67phox was similarly able to restore the activity lost in NADPH dialdehyde-treated cytosol and bound [32P]NADPH dialdehyde in a specific fashion. The activity of recombinant p67phox in cell-free oxidase assays was lost on treatment with NADPH dialdehyde. Together, these data suggest p67phox contains the catalytic NADPH-binding site of the leukocyte NADPH oxidase.

Inhibitory effect of porcine surfactant on the respiratory burst oxidase in human neutrophils. Attenuation of p47phox and p67phox membrane translocation as the mechanism

Surfactant has been shown to inhibit the production of reactive oxygen intermediates by various cells including alveolar macrophages and peripheral blood neutrophils. Superoxide O2-. production by the respiratory burst oxidase in isolated plasma membranes prepared from PMA-treated human neutrophils was significantly attenuated by prior treatment with native porcine surfactant. The effect was concentration dependent with half-maximal inhibition seen at approximately 0.050 mg surfactant phospholipid/ml. Kinetic analyses of the membrane-bound enzyme prepared from neutrophils stimulated by PMA in the presence or absence of surfactant demonstrated that surfactant treatment led to a decrease in the maximal velocity of O2-. production when NADPH was used as substrate, but there was no effect on enzyme substrate affinity. Immunoblotting studies demonstrated that surfactant treatment induced a decrease in the association of two oxidase components, p47phox and p67phox, with the isolated plasma membrane. In contrast, surfactant treatment of the cells did not alter the phosphorylation of p47phox. A mixture of phospholipids (phosphatidylcholine and phosphatidylglycerol in a 7:3 ratio) showed similar inhibition of the PMA-induced O2-. generation. Taken together, these data suggest the mechanism of surfactant-induced inhibition of O2-. production by human neutrophils involves attenuation of translocation of cytosolic components of the respiratory burst oxidase to the plasma membrane. The phospholipid components of surfactant appear to play a significant role in this mechanism.

Mutations in the promoter region of the gene for gp91-phox in X-linked chronic granulomatous disease with decreased expression of cytochrome b558

We examined the molecular defect in two kindreds with "variant" X-linked chronic granulomatous disease (CGD). Western blots of neutrophil extracts showed decreased immunoreactive cytochrome b558 components gp91-phox and p22-phox. Analysis of mRNA demonstrated reduced gp91-phox transcripts, with relative preservation of an alternative mRNA species created by transcription initiation in the third exon of the gene. Single strand conformation polymorphism analysis of the 5' flanking region of the patients' gp91-phox genes revealed an electrophoretic abnormality not detected in 40 other gp91-phox genes. Genomic sequencing demonstrated a single base change associated with CGD in each kindred: in one, adenine to cytosine at base pair-57 and in the other, thymidine to cytosine at -55. These mutations are located between the "CCAAT" and "TATA" box consensus sequences involved in eukaryotic gene transcription. Gel shift assays revealed two specific DNA-protein complexes formed between phagocyte nuclear extracts and an oligonucleotide probe representing bases -31 to -68 of the gp91-phox promoter region; the faster-migrating complex could not be formed with oligonucleotides containing either of the promoter mutations. Thus, these promoter region mutations appear to be causally related to the loss of association of a DNA-binding protein and lead to diminished gp91-phox expression, abnormal transcription initiation, and the development of CGD.

Laboratory aspects of immunology

The field of clinical immunology is advancing rapidly and will continue to grow and benefit from the knowledge gained in different areas of basic immunology. The diagnosis and evaluation of a child with a suspected primary immune defect can be a challenging task that should be done carefully using the best available laboratory resources. Simple laboratory screening tests, available to most pediatricians, can be done initially and will provide an idea of the level of general immune competence. Referral for a more detailed evaluation should be made in selected cases. A basic understanding of the tests used in immune evaluation, as well as the fact that the results may be affected by multiple variables, is important. Of equal significance is the interaction of the physician with the laboratory in which the samples will be analyzed. Proper sample collection and handling as well as prompt processing by the laboratory are crucial. Equally important is the physician's interpretation of results in the context of the pediatric population. Tests like lymphocyte studies, WBC studies, immunoglobulin subclasses, response to antigenic challenge, and certain complement assays require a higher degree of expertise and should only be sent to laboratories with experience in performing them. Physicians need to gain confidence in the power of diagnosis that the immunology laboratory brings to their patients.

Clonal growth of functionally normal and deficient neutrophils from the bone marrow of a patient with variant chronic granulomatous disease. Lack of reconstitution of oxidative burst defect by G-CSF, GM-CSF, and IFN-gamma in vitro

To evaluate the effect of colony-stimulating factors and interferon gamma on the oxidative burst capacity of neutrophils in chronic granulomatous disease (CGD) we studied the neutrophils of a patient with variant CGD both from peripheral blood and from bone marrow culture on day 7 and 14. The results revealed that preincubation of peripheral neutrophils for 24 h in medium containing recombinant human granulocyte colony-stimulating factor (rhG-CSF), recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF), and recombinant human interferon gamma (rhIFN-gamma) alone or in combination did not improve the maximal oxidative burst activity measured by MTT assay. The colonies of this patient formed in agar assay were either composed of predominantly nitroblue tetrazolium (NBT)-positive cells or completely unable to reduce NBT. Despite variable colony numbers in the presence of different cytokines, the rate of NBT-positive colonies was less than 17% of the total number of colonies. However, more than 72% of the colonies were NBT positive in controls. In liquid culture, bone marrow cells yielded a comparable rate of NBT-positive and -negative populations at day 7. These data indicate that rhG-CSF, rhGM-CSF, and rhIFN-gamma alone or rhG-CSF and rhGM-CSF in combination with rhIFN-gamma are not able to reconstitute the oxidative burst defect in CGD in vitro. Indeed, regarding colony-forming capacity, the bone marrow cells from the patient responded to CSFs as well as those from control donors did. This fact may warrant the administration of hematopoietic growth factors, at least in variant CGD, in order to enhance the absolute number of functionally normal neutrophils.

Kinetics of transfused neutrophils in peripheral blood and BAL fluid of a patient with variant X-linked chronic granulomatous disease

Patients with chronic granulomatous disease (CGD), an uncommon inherited disorder of phagocytes resulting in the defective production of reactive oxygen intermediates, are prone to bacterial and fungal infections. In the case presented, therapeutic efforts including white cell transfusions, and amphotericin B and IFN gamma administration were undertaken to treat pneumonia caused by Aspergillus fumigatus. During a phase of artificial respiration, transfused white cells in peripheral blood and bronchoalveolar lavage fluid were monitored in order to examine their kinetics and functional activity. Using flowcytometrical methods, host-derived and transfused neutrophils could be distinguished by cytochrome b558 expression using the monoclonal antibody 7D5 for immunofluorescent staining as well as by production of reactive oxygen intermediates. Transfused PMN could be detected in both compartments and their kinetics could be followed up to 24 hours after transfusion. Using flowcytometry, even small numbers of transfused PMN could be measured during episodes of extreme leukocytosis. Since functionally intact transfused PMN were found in the bronchioalveolar lavage fluid, white cell transfusions in combination with antibiotic and immunomodulating therapy should be considered a part of the therapeutic regimens for life-threatening infections in CGD patients.

Chronic granulomatous disease: a different pattern in Hong Kong?

From July 1988 to December 1989, six boys with chronic granulomatous disease were diagnosed in our institutions. Their clinical features were reviewed in order to delineate the pattern of infections which seems to have both similarities and differences when compared with published reports of Caucasian patients. The most striking differences was the lack of skin sepsis and chronic lymphadenitis in our six patients. Gram-negative organisms were the commonest pathogens while Staphylococci sp. were not isolated. Clinical features which should alert one to the diagnosis were also highlighted. Prophylactic co-trimoxazole was effective in reducing the frequency of bacterial infections. Early diagnosis is not only essential for optimal patient management but also for genetic counselling for the extended family.

A syndrome characterized by nodular eosinophilic infiltration of the skin and immunoglobulin isotype imbalance

A 9-year-old boy had recurrent acute, plaquelike, nodular infiltrations with overlying vesicles and bullae of the face and right hand. Histologically, the lesions consisted of a perivascular and periadnexal lymphohistiocytic infiltrate with many eosinophils. The lesions responded to dapsone therapy. Laboratory studies revealed blood eosinophilia, hyperimmunoglobulinemias E and G4, and hypoimmunoglobulinemias M and G1-3, which normalized after treatment. The patient's immune deviation is consistent with a transient imbalance of lymphokine production in helper T cells.

Systemic lupus erythematosus in a boy with chronic granulomatous disease: case report and review of the literature

We describe a patient with X-linked chronic granulomatous disease (CGD) who developed systemic lupus erythematosus, which was characterized by photosensitivity, malar rash, glomerulonephritis, leukopenia, hypocomplementemia, antinuclear antibodies, and anti-double-stranded DNA antibodies, at age 3. The patient's mother is an asymptomatic carrier of CGD, and her other son (the patient's half-brother) also has CGD. Neither the mother nor the brother has clinical or serologic evidence of systemic lupus erythematosus. Previous cases of discoid lupus-like skin lesions have been reported both in carriers and in patients with CGD. Our patient represents the first reported case of an individual with convincing clinical, serologic, and pathologic evidence of systemic lupus erythematosus. The association between defective host defense mechanisms and autoimmune phenomena has been described previously in patients with Job's syndrome and in patients with B cell and T cell deficiency disorders, including the acquired immunodeficiency syndrome. The relationship between the known leukocyte defects in CGD and the pathogenesis of a lupus-like illness is unclear.

Activation of the NADPH oxidase in a cell-free system from human neutrophils stimulated by phorbol myristate acetate

Kinetics of activation of the NADPH oxidase in a fully soluble cell-free system from phorbol myristate acetate (PMA)-stimulated human neutrophils were investigated. In a cell-free system in which Mg2+ and sodium dodecyl sulfate, an anionic detergent required for the activation of NADPH oxidase are contained, cytosol prepared from PMA-stimulated neutrophils failed to activate PMA-stimulated neutrophil oxidase. However, cytosol prepared from resting (control) neutrophils was capable of activating PMA-stimulated neutrophil oxidase in a cell-free system in which its Km for NADPH was almost similar to that of control neutrophil oxidase. Cytosol from PMA-stimulated neutrophils could not activate control neutrophil oxidase, although it did not contain any inhibitors of NADPH oxidase activation. These results suggest that, in PMA-stimulated neutrophils, cytosolic activation factors may be consumed or exhausted, and that the affinity for NADPH of PMA-stimulated neutrophil oxidase may be the same as that of control neutrophil oxidase.

Incidence, severity, and prevention of infections in chronic granulomatous disease

We retrospectively analyzed the frequency and nature of infections occurring in 48 patients with chronic granulomatous disease. The long-term use of trimethoprim-sulfamethoxazole and ketoconazole as a preventive therapy for infections has also been evaluated. Lymphadenitis, lung infections, dermatitis, enteral infections, and hepatic abscesses were the most frequent infections. Staphylococcus aureus, Salmonella, and Aspergillus were the main microorganisms encountered. Twelve patients died: five from lung aspergillosis, three from hepatic abscesses, two from pneumonopathy of unknown origin, one from salmonellosis, and one from another probable infection that could not be proved. The actuarial survival rate was 50% at 10 years of age, with a prolonged plateau thereafter. There was no difference in survival rates between patients with X-linked and those with autosomal recessive chronic granulomatous disease. The 8-year actuarial survival rate was significantly higher for patients born in 1978 or afterward than for patients born before 1978 (92.9% vs 70.5%). A retrospective analysis of the occurrence of bacterial and fungal infections in patients who received trimethoprim-sulfamethoxazole and ketoconazole as infection prophylaxis indicated that the former was effective against bacterial infections but that ketoconazole provided no protection against Aspergillus infections.

Partial correction of the phagocyte defect in patients with X-linked chronic granulomatous disease by subcutaneous interferon gamma

Chronic granulomatous disease, a disorder of host defense, is characterized by an impairment in the killing of microbes that results from a defect in the production of superoxide anion by phagocytes. We examined the efficacy of interferon gamma, a physiologic activator of phagocytic-cell function, in the treatment of the disease. Two subcutaneous injections of recombinant interferon gamma (0.1 mg per square meter of body-surface area per dose) were administered on consecutive days to four patients with the X-linked form of the disease. Treatment resulted in 5- to 10-fold increases in superoxide production by granulocytes and monocytes; the improvement was sustained for more than two weeks. Granulocyte bactericidal activity rose proportionally. In the two most responsive patients, both phagocytic functions reached the normal range of activity. In association with these functional changes, we observed an increase in cellular contents of phagocyte cytochrome b (a critical component of the superoxide-producing oxidase) and immunoreactive cytochrome b heavy chain (the product of the gene that is defective in X-linked chronic granulomatous disease). Levels of cytochrome b detected by spectrophotometry rose from near zero to 10 to 50 percent of normal values. This study demonstrates partial correction of the cellular defects in chronic granulomatous disease by interferon gamma and provides a basis for clinical trials of the agent.

The superoxide-forming enzymatic system of phagocytes

The formation of oxygen-derived free radicals by the phagocytes (neutrophils, eosinophils, monocytes and macrophages) is catalysed by a membrane-bound NADPH oxidase which is dormant in resting cells and becomes activated during phagocytosis or following interaction of the cells with suitable soluble stimulants. This enzyme is under investigation in many laboratories but its molecular structure remains to be clarified. Possible components such as flavoproteins, cytochrome b558, and quinones have been proposed on the basis of enzyme purification studies, effects of inhibitors, kinetic properties and analysis of genetic defects of the oxidase. An extensive discussion of the evidence for the participation of these constituents is reported. On the basis of the available information on the structure and the catalytic properties of the NADPH oxidase, a series of possible models of the electron-transport chain from NADPH to O2 is presented. Finally, the triggering mechanism of the respiratory burst is discussed, with particular reference to the stimulus-response coupling and the final modification(s) of the oxidase (phosphorylation, assembly, change of lipid environment, etc.) which are involved in its activation.

Recombinant interferon gamma augments phagocyte superoxide production and X-chronic granulomatous disease gene expression in X-linked variant chronic granulomatous disease

We examined the potential of interferon gamma (IFN-gamma) to ameliorate the physiologic defect of chronic granulomatous disease (CGD) by studying its effects on CGD phagocyte superoxide generation, NADPH oxidase kinetics, cytochrome b559 content, and expression of X-CGD (the gene for the X-linked disease). Granulocytes and macrophages from three patients in two kindreds with "variant" X-linked CGD (i.e., with very low, but detectable, baseline superoxide-generating activity) responded to IFN-gamma with enhanced nitroblue tetrazolium reduction and two- to eightfold increases in superoxide generation. IFN-gamma did not augment the respiratory burst activity of phagocytes from patients with "classic" CGD (i.e., no detectable baseline superoxide generation) or autosomal variant CGD. Incubation of a responding patient's granulocytes with IFN-gamma nearly doubled the maximal velocity for the NADPH oxidase, but did not change its abnormal Michaelis constant. Although the interferon-treated CGD granulocytes produced superoxide at a rate 40% of normal, the cytochrome b spectrum remained undetectable. IFN-gamma treatment of cultured monocytes from an IFN-gamma-responsive CGD patient increased the steady state level of RNA transcripts from the X-CGD gene from barely detectable up to approximately 5% of normal.

Subcellular distribution of Ca2+ pumping sites in human neutrophils

The distribution of nonmitochondrial Ca2+ pumping sites and the site of action of inositol 1,4,5-trisphosphate (Ins 1,4,5-P3) were studied in subcellular fractions of human neutrophils. In homogenates, two different Ca2+ pools could be observed: a mitochondrial Ca2+ pool and a nonmitochondrial, ATP-dependent, Ins 1,4,5-P3-responsive Ca2+ pool. When the homogenate was separated into microsomes, primary granules, and secondary granules, the nonmitochondrial Ca2+ pumping and the Ins 1,4,5-P3-induced Ca2+ release occurred only in the microsomal fraction. In a gradient developed to separate different microsomal organelles, maximal Ca2+ pumping activity occurred in fractions of low densities. Correlations between Ca2+ uptake and organelle markers were negative for the endoplasmic reticulum (r = -0.49) and positive for plasma membrane (r = 0.47), Golgi (r = 0.62), and endosomes (r = 0.96). Because the Ca2+ pumping organelles in these fractions were insensitive to micromolar vanadate and digitonin treatment, they are unlikely to be plasma membrane vesicles. We conclude first that microsomal fractions of human neutrophils contain organelles that lower the ambient free Ca2+ concentration and respond to Ins 1,4,5-P3. Second, granules are not involved in intracellular Ca2+ regulation in neutrophils. Third, nonendoplasmic reticulum organelles, such as endosomes, Golgi elements, or yet undefined specialized structures, play a major role in intracellular Ca2+ homeostasis in human neutrophils.

Platelet-derived growth factor stimulates phagocytosis and blocks agonist-induced activation of the neutrophil oxidative burst: a possible cellular mechanism to protect against oxygen radical damage

The effect of platelet-derived growth factor (PDGF) on agonist-induced activation of the superoxide-generating oxidative burst in human neutrophils was tested. PDGF had no effect on the resting level of superoxide generation but inhibited both the rate and the extent of fMet-Leu-Phe-stimulated superoxide production in a dose-dependent manner. The concentration required to inhibit the response by 50% was 95 +/- 26 pM (n = 10). PDGF also blocked activation by other receptor-mediated agonists such as the complement protein C5a and opsonized zymosan, but not by phorbol myristate acetate or arachidonate, both of which may act at postreceptor sites. The growth factor, however, had no effect on the binding of fMet-Leu-Phe to its receptor. PDGF in concentrations that blocked the oxidative burst stimulated phagocytosis of opsonized latex particles. Thus, PDGF functions as a heterologous "down-regulator" of receptor-mediated activation of the neutrophil oxidative burst and an activator of phagocytosis. A model for a feedback regulatory loop between platelets and neutrophils is proposed.

Discoid lupus erythematosus-like skin lesions in a patient with autosomal recessive chronic granulomatous disease

A case of chronic granulomatous disease (CGD) in a 32-year-old female with two episodes of opportunistic infections is described. At the age of 29 the patient was suspected to be a carrier of X-linked CGD on the basis of discoid lupus erythematosus-like skin lesions. No respiratory burst activity, as measured by phorbol myristate acetate stimulated superoxide production, was observed in isolated neutrophils of the patient. Membrane-rich fractions elicited no superoxide production in the presence of NADPH. The neutrophil content of cytochrome b-245 was within normal range. Family investigations revealed neither cellular abnormalities nor any history of skin diseases or opportunistic infections in first degree relatives. The parents of the patient were first cousins. On the basis of family history and the in-vitro assessment of neutrophil function, the patient is believed to have autosomal recessive CGD. The presented case illustrates that lupus erythematosus-like skin lesions are not restricted to female carriers of X-linked CGD, but may also be found in the autosomal recessive type of the disease.

Phagocyte defects

Although inherited forms of phagocyte defects affect a small proportion of the general population, their clinical course can be altered dramatically by a physician's awareness of these diseases and modifications of the approach to and treatment of affected patients. The most common syndromes are chronic granulomatous disease of childhood (CGD), the Chediak-Higashi syndrome (CHS), the hyperimmunoglobulin-E-recurrent infection (Job's) syndrome (HIE), and myeloperoxidase (MPO) deficiency. CGD patients have defects in the oxidative metabolism involved in killing catalase-positive organisms. CHS patients have giant granules defective in fusing with phagosomes and subsequent killing of ingested organisms. HIE patients have abnormal chemotaxis and elevated IgE levels and are susceptible to skin infections with Staphylococcus aureus and recurrent sinopulmonary infections. MPO-deficient patients often go undetected since they rarely have recurrent infections unless they have a concomitant disease such as diabetes mellitus. Patients with a recently described syndrome, C3bi receptor deficiency, have recurrent bacterial infections and persistent leukocytosis, and their neutrophils have abnormal adherence and phagocytosis. The absence of specific granules is a more rare entity but these patients also have recurrent infections thought to be secondary to a chemotactic defect and a minor abnormality of microbial killing exhibited by their neutrophils. This review will focus on the clinical presentation and management of these patients.

Inhibition of growth of HeLa and WI-38 cells by dehydroepiandrosterone and its reversal by ribo- and deoxyribonucleosides

Dehydroepiandrosterone (DHEA), an adrenal steroid of no known biological function, is a potent inhibitor of mammalian glucose-6-phosphate dehydrogenase (G6PDH). DHEA inhibited the growth of two stains of HeLa and WI-38 cells in culture. One of the HeLa strains, TCRC-2, was about 10x as sensitive to growth inhibition as the two other cell lines. The G6PDH activity in cell extracts of HeLa TCRC-2 was also much more sensitive to DHEA inhibition than the G6PDH activities of the other cell lines. The addition of a combination of four deoxyribonucleosides and four ribonucleosides to the culture medium overcame the DHEA-induced growth inhibition in the HeLa TCRC-2 line.

A study of 25 patients with chronic granulomatous disease: a new classification by correlating respiratory burst, cytochrome b, and flavoprotein

Twenty-five patients suffering from chronic granulomatous disease (CGD) and their families were investigated. Defects in the superoxide generating system were characterized at the level of the heme-containing cytochrome b and of the FAD-containing flavoprotein, both localized in the plasma membrane of granulocytes. It was confirmed that in most of the typical cases (18 of 22), the complete inability of superoxide generation was associated with the absence of detectable cytochrome b. Mothers but not fathers of such male patients were characterized by a diminished content of cytochrome b, confirming that the affected gene is localized on the X chromosome. In contrast, the granulocytes of four other typical patients (two female and two male) contained normal amounts of cytochrome b, whereas oxidative activity was absent. Since no abnormality of oxidative activity as well as of cytochrome b was found in granulocytes of the mothers and fathers of these patients, an autosomal recessive mode of inheritance of the disease is probable. The flavoprotein deficiency found in the granulocytes of four male patients was always associated with an absence of detectable cytochrome b. This could indicate a structural relationship between flavoprotein and cytochrome b (e.g., a flavocytochrome). Three further patients with mild X-linked CGD contrasted with the patients with severe or classic X-linked disease; the oxidative activity of their phagocytes was diminished but not absent, and the cytochrome b present, albeit in small amounts.

Leishmania donovani: surface membrane acid phosphatase blocks neutrophil oxidative metabolite production

We show that a purified preparation of the prominent tartrate-resistant acid phosphatase (E.C.3.1.3.2), isolated from the external surface of the intracellular parasite Leishmania donovani (promastigote form), inhibits toxic oxidative metabolite production of neutrophils. Preincubation of a neutrophil suspension (2.5 X 10(6) cells/ml) for 15 min at 37 C with 250 units (1 unit equals 1 nmole of 4-methylumbelliferyl phosphate cleaved per hr at pH 5.5) of the acid phosphatase in Krebs-Ringer phosphate buffer (pH 7.4) decreased O2 consumption, O2- production, and H2O2 production of N-formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe)-stimulated neutrophils to 15-25% of control values. The acid phosphatase also affected concanavalin A-stimulated O2-production by neutrophils, but had no effect on the rate of phorbol myristic acetate-stimulated O2- production, chemotactic peptide binding, degranulation, or membrane depolarization. Addition of an acid phosphatase inhibitor (Complex E; (NH4)6[P2Mo18O62] X 9H2O) to suspensions of opsonized promastigotes and neutrophils resulted in a threefold or greater enhancement of O2- production. These results suggest a possible pathophysiologic role for the acid phosphatase of L. donovani promastigotes.

Chemotactic peptide activation of human neutrophils and HL-60 cells. Pertussis toxin reveals correlation between inositol trisphosphate generation, calcium ion transients, and cellular activation

The mechanism of neutrophil activation by the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (FMLP) has been studied by pretreatment of human neutrophils with pertussis toxin. Upon stimulation with FMLP, the cytosolic-free calcium concentration, [Ca2+]i, is increased both by stimulation of calcium influx and mobilization of cellular calcium. We have measured [Ca2+]i as well as the generation of the phospholipid breakdown product inositol trisphosphate (IP3), which is thought to mediate Ca2+ mobilization. As the phosphoinositide pool in human neutrophils is difficult to prelabel with [3H]myoinositol, experiments were also carried out in the cultured human promyelocytic leukemia cell line HL-60 after differentiation with dimethylsulfoxide. Pertussis toxin pretreatment of both cell types inhibited FMLP stimulated membrane depolarization, exocytosis, and superoxide production in a dose-dependent manner. This toxin effect was selective for the receptor agonist, since stimulation of these parameters by two substances bypassing the transduction mechanism, the calcium ionophore ionomycin and the phorbolester phorbol myristate acetate, were unaffected. Rises in [Ca2+]i, as well as generation of IP3 in response to FMLP, were inhibited in parallel; for the inhibition of functional responses, slightly lower toxin concentrations were required. The attentuation of the [Ca2+]i rise was more marked in the absence of extracellular calcium, i.e., when the rise is due only to calcium mobilization. The results provide evidence that phospholipase C stimulation by FMLP resulting in IP3 generation is involved in the signal transduction mechanism. Coupling of FMLP receptor occupancy to phospholipase C activation is sensitive to pertussis toxin, suggesting the involvement of a GTP binding protein (N protein), which has been shown to be a pertussis toxin substrate. The parallel changes in [Ca2+]i and IP3 further support the hypothesis that IP3 is the calcium-mobilizing mediator in FMLP-activated cells.

Molecular heterogeneity in chronic granulomatous disease: a human model of defective phagocyte superoxide production

Chronic granulomatous disease (CGD) is a genetically transmitted disorder thought to result from defect(s) in the activation or turnover of the NADPH dependent O2- generating oxidase enzyme system of human neutrophils and monocytes. The normal oxidase may be a flavoprotein-cytochrome b559 complex; therefore, these components of the oxidase were quantitated in the neutrophils from patients and family members of two unrelated CGD kindreds. The male propositus from an X-linked recessive kindred had a neutrophil oxidase fraction with low FAD content (26 pmol/mg protein) and undetectable cytochrome b559 (less than 5 pmol/mg protein). The male propositus from an autosomal recessive kindred had a neutrophil oxidase fraction with low FAD content (34 pmol FAD/mg protein), but normal cytochrome b559 content (170 pmol cytochrome b559/mg protein). Both parents of this latter CGD patient had normal FAD and cytochrome b559 content in their neutrophil oxidase fraction. We conclude that the carrier state in certain X-linked recessive female carriers of CGD can be detected by partial deficiencies of both flavoprotein and cytochrome b559 components of the oxidase, whereas presumed heterozygous carriers of certain autosomal recessive CGD kindreds cannot be detected by this means.

Modulation of cytosolic-free calcium transients by changes in intracellular calcium-buffering capacity: correlation with exocytosis and O2-production in human neutrophils

The intracellularly trapped fluorescent calcium indicator, quin 2, was used not only to monitor changes in cytosolic-free calcium, [Ca2+]i, but also to assess the role of [Ca2+]i in neutrophil function. To increase cytosolic calcium buffering, human neutrophils were loaded with various quin 2 concentrations, and [Ca2+]i transients, granule content release as well as superoxide [O2-] production were measured in response to the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (fMLP) and the calcium ionophore ionomycin. Receptor-mediated cell activation induced by fMLP caused a rapid rise in [Ca2+]i. The extent of [Ca2+]i rise and granule release were inversely correlated with the intracellular concentration of quin 2, [quin 2]i. These effects of [quin 2]i were more pronounced in the absence of extracellular Ca2+. The initial rate and extent of fMLP-induced O2- production were also inhibited by [quin 2]i. The rates of increase of [Ca2+]i and granule release elicited by ionomycin were also inversely correlated with [quin 2]i in Ca2+-containing medium. As the effects of ionomycin, in contrast to those of fMLP, are sustained, the final increase in [Ca2+]i and granule release were not affected by [quin 2]i. A further reduction of fMLP effects was seen when intracellular calcium stores were depleted by incubating the cells in Ca2+-free medium with ionomycin. The specificity of quin 2 effects on cellular calcium were confirmed by loading the cells with Anis/AM, a structural analog of quin 2 with low affinity for calcium which did not inhibit granule release. In addition, functional responses to phorbol myristate acetate (PMA), which stimulates neutrophils without raising [Ca2+]i, were not affected by [quin 2]i. The findings indicate that rises in [Ca2+]i control the rate and extent of granule exocytosis and O2-generation in human neutrophils exposed to the chemotactic peptide fMLP.

Chronic granulomatous disease in two sisters

Two sisters with chronic granulomatous disease (CGD) have been studied. The diagnosis was suggested by the histopathological findings from the spleen and lymph nodes of the proband and confirmed by the low values obtained in the following tests performed on polymorphonuclear leukocytes (PMN): chemiluminescence, nitroblue tetrazolium (NBT) reduction, killing of Staphylococcus aureus, and O2- production. NADPH oxidase activity was not detected in the homogenates of the patients' PMN but cytochrome b was normally present. In addition, PMN depolarization induced by phorbol-myristate acetate was absent, thus suggesting a defect of the activation mechanism of the respiratory enzyme. The normal depolarization induced by ouabain indicated that the membrane polarity regulated by the Na/K pump in the patients' cells was not affected. The low, but not completely absent, respiratory activity of the patients' PMN could suggest an X-linked mode of inheritance with incomplete Lyonization. From a clinical point of view, one sister had mild symptoms whereas the other was almost symptomless, thus confirming once more the heterogeneity of CGD syndrome.