Optimal Aspergillus fumigatus and Asp f 1 serum IgG cut-offs for the diagnosis of allergic bronchopulmonary aspergillosis

BACKGROUND

The presence of IgG antibodies (Abs) to Aspergillus fumigatus (Af) is a crucial diagnostic criterion for allergic bronchopulmonary aspergillosis (ABPA). Although precipitation is traditionally used to document IgG Abs, anti-Af serum IgG levels can also be measured by enzyme immunoassay (EIA). However, there are insufficient data on the optimal cut-offs to assess diagnostic performance of the EIA method. This study aimed to determine cut-off levels of IgG binding crude Af extracts or recombinant Asp f 1 (by ImmunoCAP®) and to compare their efficacy for ABPA diagnosis with Af-precipitating Abs.

METHODS

The age distribution of levels of IgG to crude extracts of Af (Af-IgG) and recombinant Asp f 1 (Asp f 1-IgG) was established using sera from 694 healthy controls (HC). Receiver operating characteristic analysis for Af-IgG and Asp f 1-IgG levels for the purpose of ABPA diagnosis was performed in 306 Af-sensitized asthma patients (including 49 ABPA), and cut-offs were determined.

RESULTS

An age-dependent decline in the levels of Af-IgG was observed in HC. Thus, cut-offs for Af-IgG levels were determined separately by age as 60 mg/L for patients aged <55 years, and 45 mg/L for those aged ≥55 years. For Asp f 1-IgG, 6.6 mg/L was set as the cut-off regardless of age. Although such IgG testing by EIA allowed a sufficiently good diagnostic performance, Af-precipitating Abs had better diagnostic applicability for ABPA.

CONCLUSIONS

We determined cut-offs for Af-IgG and Asp f 1-IgG measured by EIA, which can be useful in clinical settings where precipitating Abs are unavailable.

Clinical and radiological signs of ABPA associated with airways infection with Aspergillus in the absence of specific IgE

Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity reaction to Aspergillus that mainly affects patients with asthma. For diagnosis, elevated serum IgE level are needed according to Greenberger and Patterson criteria. We report a case of 43 years-old woman who developed ABPA with productive cough, fever and radiological findings of multiple confluent areas of consolidation in both upper lobes. Laboratory tests showed elevated peripheral eosinophil counts (9.3 x 10(3)/ml). In bronchial washing A. galactomannans and A. Fumigatus were isolated, although we found normal levels of serum IgE, and the absence of serum IgG and IgE antibodies to Aspergillus and A. galactomannans. In conclusion, clinical and radiological signs of ABPA can be associated with Aspergillus infection also in the absence of a specific serum antibody reaction.

Suspected Allergic Bronchopulmonary Aspergillosis Cases in Adult Bronchial Asthma Patients Attending a Tertiary Care Clinic

Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity reaction to Aspergillus species (generally Aspergillus fumigatus) that occurs almost exclusively in patients with asthma or, less commonly, cystic fibrosis. Immune responses to Aspergillus antigens cause airway obstruction and, if untreated, bronchiectasis and pulmonary fibrosis. Our objective was to define the clinical characteristics, laboratory and radiological findings of suspected ABPA cases among a cohort of Egyptian patients with bronchial asthma. 52 moderate and severe asthma patients were recruited from the Allergy and Immunology clinic at Ain Shams University hospitals. Patients were subjected to history taking for asthma symptoms, skin test with Aspergillus fumigatus antigen, total IgE level, peripheral blood eosinophilia, chest x-ray and high resolution CT chest. 27 patients had positive skin prick and /or intradermal test to Aspergillus fumigatus antigen, and 11 (21.2%) of them fulfilled 4 of the criteria for ABPA diagnosis. Patients with suspected ABPA had significantly higher serum total IgE levels (median (IQR) = 625 IU/ml (514.9-762) with P-value <0.0001). Our study suggests a high frequency of suspected ABPA cases for further confirmation by appropriate diagnostic tests; there is a need for better recognition of ABPA as it is yet under recognized in Egypt Clinicians ought to have a high index of suspicion for ABPA while managing any patient with bronchial asthma to detect ABPA prior to development of irreversible complications.

Allergic bronchopulmonary aspergillosis

There remains a lack of agreement on diagnostic criteria and approaches to treatment of patients with allergic bronchopulmonary aspergillosis (ABPA). The results of a survey of American Academy of Allergy, Asthma, & Immunology members regarding these 2 issues are presented and compared for concordance with published recommendations. The literature was reviewed for pertinent reports, and an electronic survey was conducted of American Academy of Allergy, Asthma, & Immunology members and fellows regarding diagnostic criteria, numbers of patients evaluated for ABPA, and treatment approaches. From 508 respondents to the survey sent to 5155 US physicians in the American Academy of Allergy, Asthma, & Immunology database of members and fellows, 245 health professionals (48%) had treated at least 1 patient with ABPA in the previous year. For the diagnosis of ABPA, there was a difference in the threshold concentration of total serum IgE because 44.9% used ≥417 kU/L, whereas 42.0% used ≥1000 kU/L. Analysis of these findings suggests that ABPA might be underdiagnosed. With regard to pharmacotherapy, oral steroids were recommended for 97.1% of patients and oral steroids plus inhaled corticosteroids plus antifungal agent were used with 41.2% of patients. The armamentarium for treatment of ABPA includes oral corticosteroids as the initial treatment with inhaled corticosteroids used for management of persistent asthma. Azoles remain adjunctive. Published experience with omalizumab has been limited.

Anti IgE antibody as treatment of allergic bronchopulmonary aspergillosis in a patient with cystic fibrosis

Allergic bronchopulmonary aspergillosis (ABPA) occurs in 7-9% of patients with cystic fibrosis (CF) and causes a worsening of lung function and respiratory symptoms. Standard treatment of ABPA consists of oral steroids; however, higher corticosteroid therapy associated to antifungal agent (itraconazole) long-term treatments are often required to reduce respiratory exacerbations and to prevent progressive lung damage. Here we describe the case of a girl with CF who experienced clinical and functional improvement over 12-months treatment with omalizumab. At birth, our patient was diagnosed with mild-to-moderate CF and from childhood she underwent annual cycles of antibiotic and corticosteroid therapies. At 12 years, she presented with a worsening respiratory condition, asthma symptoms and reduced lung function (FEV1 of 78%). Blood tests showed an increased concentration of plasma total IgE and positive specific IgE antibodies to Aspergillus fumigatus; allergic skin tests were also positive for A. fumigatus. The patient started steroid therapy but had impaired glucose tolerance due to long-term steroid use. Subcutaneous omalizumab 300 mg every two weeks was initiated and after 14 weeks she had improved respiratory symptoms (FEV1 99%) and a marked reduction in the use of systemic antibiotic and corticosteroid therapies. No side effects were reported. Our case shows that therapy with omalizumab for a prolonged period can resolve symptoms of asthma.

[The role of allergological tests in allergic bronchopulmonary aspergillosis (ABPA)]

Allergic Bronchopulmonary Aspergillosis (ABPA) is an uncommon respiratory condition in which Asp. spp spores and mycelia inhalation trigger an immuno allergic inflammatory response in the bronchial airways. ABPA mostly develops in asthmatic and cystic fibrosis patients. The true prevalence of ABPA in not known. It is important to exclude ABPA in all asthmatics with positive skin reactivity to Aspergillus. Currently, a number of allergens from A. fumigatus have been cloned and the mRNA was purified - these are the recombinant antigens which can be used to distinguish between ABPA and fungal sensitization. IgE specific for Asp f 4 and Asp f 6 are restricted to ABPA patients and have a sensitivity and specificity of 90% and 100%, respectively. Aspergillus hipersensitivity can be demonstrated using in vivo (skin prick test) and in vitro methods (specific IgE and IgG, serum precipitins). In ABPA skin prick test is almost always positive. Normal levels of total IgE exclude ABPA. Serum total and specific IgE vary according to disease activity and are usefull for monitoring the treatment.

Clinical relevance of peripheral blood eosinophil count in allergic bronchopulmonary aspergillosis

BACKGROUND AND AIMS

Currently, there is not a uniform consensus regarding the number of criteria or specific cut-off values for the variety of tests that are used to diagnose allergic bronchopulmonary aspergillosis (ABPA). Traditionally, an eosinophil count >1000 cells/μl is considered an important criterion in the diagnosis of ABPA. The goal of this study was to delineate the significance of the peripheral blood eosinophil count in the diagnosis of ABPA, and the relationship between eosinophil counts and lung function and immunological and radiological parameters.

METHODS

This study was a retrospective analysis of the data from ABPA patients who were managed in our chest clinic. Based on their eosinophil count, the patients were classified into the following three categories: <500, 500-1000 and >1000 cells/μl. The spirometric, immunological and radiological characteristics were also assessed.

RESULTS

We studied 108 males and 101 females with a combined mean (±SD) age of 34.1±12.5years. The median (IQR) eosinophil count at diagnosis was 850 (510-1541)cells/μl, and 60% of the patients had an eosinophil count of <1000 cells/μl. We found no relationship between eosinophil count and lung function using spirometry and other immunological parameters. The median eosinophil count was higher in patients with an high resolution computed tomography (HRCT) chest finding of bronchiectasis (986 vs. 620, p<0.001) vs. those without and in patients with high-attenuation mucus (1200 vs. 800, p<0.001) compared to those without high-attenuation mucus.

CONCLUSIONS

A peripheral blood eosinophil count has limited utility in the diagnosis of ABPA, and there is no relationship between eosinophil count and lung function or other immunological parameters. The higher eosinophil count that we observed in patients with central bronchiectasis or high-attenuation mucus suggests that eosinophils are primary mediators of inflammatory activity in ABPA.

[Diagnostics of mycotic sensitization in children with allergic respiratory diseases by the ImmunoCAP technique]

The need to verify sensitization to mycotic allergens in children with allergic bronchopulmonary diseases is due to the severity of their clinical course, the high frequency of complications, and the inadequate efficiency of conventional treatment regimens. The sensitivity of most techniques used in clinical practice to estimate the level of specific artibodies to mycotic antigens is inadequately high. Recently clinically introduced high-technology diagnostic methods allow one to attack the problem at a qualitatively new level. The application of one of these methods, namely the highly sensitive semiautomatic diagnostic technology ImmunoCAP, permits the determination of the rates of IgE- and IgG-associated specific immune reactions in children with allergic respiratory diseases.

Comparison of serum markers for allergic bronchopulmonary aspergillosis in cystic fibrosis

The diagnosis of allergic bronchopulmonary aspergillosis (ABPA) in cystic fibrosis (CF) is a challenge. Thymus- and activation-regulated chemokine (TARC) has recently been reported to play a role in ABPA. The aim of this study was to compare the diagnostic value of TARC with that of known serological markers for diagnosis of ABPA in CF patients. The present study longitudinally followed 48 CF patients, of whom 12 had a diagnosis of ABPA according to Nelson's criteria, for 1-8 yrs with repeated measurements of serum total immunoglobulin (Ig)E, specific Aspergillus fumigatus IgE and IgG, specific IgE against recombinant A. fumigatus allergens (rAsp f) 1, 3, 4 and 6, and TARC. Median (interquartile range) TARC levels were 589 (465-673) pg x mL(-1) in ABPA patients and 232 (189-289) pg x mL(-1) in non-ABPA patients. Receiver operating characteristic curves revealed that TARC was superior to the other markers for diagnosis of ABPA. Diagnostic accuracy was greater for TARC (93%) than for total IgE (74%), or rAsp f 4 (75%) or f 6 (79%). The present study indicates that thymus- and activation-regulated chemokine may be useful in the diagnosis of allergic bronchopulmonary aspergillosis in cystic fibrosis patients. However, larger studies are needed before thymus- and activation-regulated chemokine can routinely be used in diagnostic algorithms.

Allergic bronchopulmonary aspergillosis' diagnosis remains a challenge

INTRODUCTION

Allergic bronchopulmonary aspergillosis (ABPA) is a complex disease, triggered by a hypersensitivity reaction to the allergens of Aspergillus fumigatus, a fungus that opportunistically colonizes the lungs of patients with asthma. The diagnosis of ABPA is difficult. A major problem is the lack of standardized allergens used in the determination of specific IgE, but the use of recombinant allergens has been proposed to overcome this. The aim of the present study is to evaluate whether serological tests for IgE specific to recombinant allergens of A. fumigatus (rAsp) can aid in the detection of sensitization to this fungus and in the diagnosis of ABPA.

METHODS

This was an observational, cross-sectional study. The diagnosis of ABPA, using classical criteria, was searched in 65 asthmatics patients with immediate cutaneous reactivity to A. fumigatus. After that, serum titers of IgE against rAsp f 1, rAsp f 2, rAsp f 3, rAsp f 4 and rAsp f 6 were determined. In order to compare the differences between patients with confirmed and excluded diagnosis of ABPA, the two-tailed Fisher's exact test was used.

RESULTS

Although 19 of 65 patients had IgE against at least one recombinant, the disease was diagnosed in only six patients by classical criteria. One of them had IgE against all recombinant allergens tested and another one had antibody against Asp f 3.

DISCUSSION

The determination of serum IgE against recombinant A. fumigatus allergens in this group was not helpful to make the diagnosis of ABPA, neither to detect sensitization to fungus.

A rapid HPLC method with fluorometric detection for determination of plasma itraconazole and hydroxy-itraconazole concentrations in cystic fibrosis children with allergic bronchopulmonary aspergillosis

The development and validation of a simple, rapid and selective high-performance liquid chromatography (HPLC) method is described for the quantitation of itraconazole and hydroxy-itraconazole in 100 microL of plasma from a paediatric population. The mobile phase of methanol (75% v/v) and water (25% v/v) was pumped at 1 mL/min through a C18 Symmetry (3.9 mm i.d. x 150 mm) cartridge. Using a protein-precipitation method, 100 microL internal standard (IS) solution (R051012, 555 microg/L in acetonitrile) were added to 100 microL of plasma followed by 10 microL zinc sulphate solution (20% w/v). Itraconazole, hydroxy-itraconazole and IS eluted at 4.7, 8.3 and 12.5 min, respectively and were detected fluorometrically at 250 nm (excitation) and 380 nm (emission). Recoveries were 87.1-96.7%. Calibrations in drug-free plasma were linear (r2 > 0.99) from 50 to 2000 microg/L, using 1/c2 (c = concentration) weighting. Intraday and interday imprecision (CV%) was 4.8-17.3 and 6.3-16.6% for itraconazole, and 4.6-17.9 and 7.02-18.4% for hydroxy-itraconazole. Inaccuracy was -7.1 to -14.7% for itraconazole and -0.1 to -9.7% for hydroxy-itraconazole. The clinical application of this method was demonstrated by measurement of itraconazole and hydroxy-itraconazole in plasma samples drawn from paediatric cystic fibrosis patients, who were prescribed itraconazole for treatment of allergic bronchopulmonary aspergillosis.

Chemokines indicate allergic bronchopulmonary aspergillosis in patients with cystic fibrosis

RATIONALE

Allergic bronchopulmonary aspergillosis (ABPA) is characterized by a Th2 immune response. Mouse models suggest a critical role for the Th2 chemokines thymus- and activation-regulated chemokine (TARC) and macrophage-derived chemokine (MDC) in ABPA.

OBJECTIVES

To determine whether serum levels of TARC and MDC characterize ABPA in patients with cystic fibrosis (CF) and to examine longitudinally if levels of TARC and MDC indicate ABPA exacerbations in patients with CF.

METHODS

Levels of TARC and MDC and levels of Th1 (IL-12 and IFN-gamma) and Th2 (IL-4, IL-5, and IL-13) cytokines were analyzed in serum of 16 patients with CF with ABPA, six non-CF patients with asthma with ABPA, 13 patients with CF colonized with Aspergillus fumigatus, six patients with CF sensitized to A. fumigatus, 12 atopic patients with CF, and 13 non-CF atopic control subjects by ELISA. The longitudinal course of TARC, MDC, and IgE levels was assessed during ABPA episodes.

RESULTS

Patients with ABPA had significantly higher serum levels of TARC compared with the other patient groups. Cytokine levels did not differ among the patient groups. Longitudinally, levels of TARC indicated ABPA exacerbations in patients with CF more clearly than IgE levels. In patients with CF and ABPA, levels of TARC correlated positively with specific IgE to A. fumigatus and rAsp f4.

CONCLUSIONS

Serum levels of TARC differentiate patients with CF or patients with asthma with ABPA from patients with CF colonized with or sensitized to A. fumigatus, atopic patients with CF, and atopic control subjects. Longitudinally, levels of TARC indicate ABPA exacerbations, suggesting TARC as a marker for identification and monitoring of ABPA in patients with CF.

Second-hand smoke increases nitric oxide and alters the IgE response in a murine model of allergic aspergillosis

This study was performed to determine the effects of environmental tobacco smoke (ETS) on nitric oxide (NO) and immunoglobulin (Ig) production in a murine model of allergic bronchopulmonary aspergillosis (ABPA). Adult BALB/c mice were exposed to aged and diluted sidestream cigarette smoke from day 0 through day 43 to simulate “second-hand smoke”. During exposure, mice were sensitized to soluble Aspergillus fumigatus (Af) antigen intranasally between day 14 and 24. All Af sensitized mice in ambient air (Af + AIR) made elevated levels of IgE, IgG1, IgM, IgG2a and IgA. Af sensitized mice housed in ETS (Af + ETS) made similar levels of immunoglobulins except for IgE that was significantly reduced in the serum and bronchoalveolar lavage (BAL). However, immunohistochemical evaluation of the lung revealed a marked accumulation of IgE positive cells in the lung parenchyma of these Af + ETS mice. LPS stimulation of BAL cells revealed elevated levels of NO in the Af + AIR group, which was further enhanced in the Af+ETS group. In vitro restimulation of the BAL cells on day 45 showed a TH0 response with elevated levels of IL3, 4, 5, 10 and IFN-γ. However, by day 28 the response shifted such that TH2 cytokines increased while IFN-γ decreased. The Af + ETS group showed markedly reduced levels in all cytokines tested, including the inflammatory cytokine IL6, when compared to the Af+AIR group. These results demonstrate that ETS affects ABPA by further enhancing the NO production and reduces the TH2 and the inflammatory cytokines while altering the pattern of IgE responses.

Tryptophan residue is essential for immunoreactivity of a diagnostically relevant peptide epitope of A. fumigatus

The role of tryptophan (Trp17) in immunoreactivity of P1, the diagnostically relevant peptide from a major allergen/antigen of Aspergillus fumigatus, was evaluated by chemically modifying tryptophanyl residue of P1. In BIAcore kinetic studies, unmodified P1 showed a 100-fold higher binding with ABPA (Allergic Bronchopulmonary Aspergillosis) patients' IgG [KD (equilibrium dissociation constant) = 2.74 e(-8) +/- 0.13 M] than the controls' IgG (KD = 2.97 e(-6) +/- 0.14 M), whereas chemically-modified P1 showed similar binding [KD patients' IgG = 3.25 e(-7) +/- 0.16 M, KD controls' IgG = 3.86 e(-7) +/- 0.19 M] indicating loss of specific immunoreactivity of P1 on tryptophan modification. Modified P1 showed loss of specific binding to IgE and IgG antibodies of ABPA patients in ELISA (Enzyme-Linked Immunosorbent Assay). The study infers that tryptophan residue (Trp17) is essential for immunoreactivity of P1.

Second-hand smoke increases bronchial hyperreactivity and eosinophilia in a murine model of allergic aspergillosis

Involuntary inhalation of tobacco smoke has been shown to aggravate the allergic response. Antibodies to fungal antigens such as Aspergillus fumigatus (Af) cause an allergic lung disease in humans. This study was carried out to determine the effect of environmental tobacco smoke (ETS) on a murine model of allergic bronchopulmonary aspergillosis (ABPA). BALB/c mice were exposed to aged and diluted sidestream cigarette smoke to simulate 'second-hand smoke'. The concentration was consistent with that achieved in enclosed public areas or households where multiple people smoke. During exposure, mice were sensitized to Af antigen intranasally. Mice that were sensitized to Af antigen and exposed to ETS developed significantly greater airway hyperreactivity than did mice similarly sensitized to Af but housed in ambient air. The effective concentration of aerosolized acetylcholine needed to double pulmonary flow resistance was significantly lower in Af + ETS mice compared to the Af + AIR mice. Immunological data that supports this exacerbation of airway hyperresponsiveness being mediated by an enhanced type 1 hypersensitivity response include: eosinophilia in peripheral blood and lung sections. All Af sensitized mice produced elevated levels of IL4, IL5 and IL10 but no IFN-γ indicating a polarized Th2 response. Thus, ETS can cause exacerbation of asthma in ABPA as demonstrated by functional airway hyperresponsiveness and elevated levels of blood eosinophilia.

Use of a synthetic peptide epitope of Asp f 1, a major allergen or antigen of Aspergillus fumigatus, for improved immunodiagnosis of allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is an immunologically complex allergic disorder caused by the fungal pathogen Aspergillus fumigatus. Elevated levels of total immunoglobulin E (IgE), specific IgE, and IgG antibodies in sera are important immunodiagnostic criteria for ABPA. International reference standards or standardized immunodiagnostic assays are not available due to a lack of well-defined diagnostic antigens. The present study was carried out to identify and evaluate the immunodiagnostic relevance of synthetic epitopic peptides of Asp f 1, a major allergen, antigen, or cytotoxin of A. fumigatus. Five overlapping peptides were synthesized from the N terminus of Asp f 1, one of the potential immunodominant regions predicted by algorithmic programs. The 11-amino-acid synthetic peptide (P1) significantly inhibited both IgG binding (89.10% +/- 4.45%) and IgE binding (77.32% +/- 3.38%) of the standardized diagnostic antigen (SDA) (a well-defined pool of diagnostically relevant allergens and antigens of A. fumigatus). With a panel of sera of ABPA patients, allergic patients with skin test negativity to A. fumigatus, and healthy individuals, P1 showed a higher diagnostic efficiency than SDA (specific IgG, 100%; specific IgE, 98.3%). The diagnostic efficiency of P1 could be attributed to the presence of homologous epitopes in various immunodominant allergens or antigens of A. fumigatus. The ability of P1 to induce histamine release from sensitized mast cells and a Th2 type of cytokine profile in peripheral blood mononuclear cells of ABPA patients suggests its potential for use in intradermal testing. P1 could be further explored for development of a standardized, specific, and sensitive immunodiagnostic test for aspergillosis.

Surfactant protein D in serum from patients with allergic bronchopulmonary aspergillosis

Surfactant protein D (SP-D) interacts with Aspergillus fumigatus and is strongly increased in the lavage from animals with acute allergic reactions to the fungus, suggesting a central role for SP-D. As the course of cystic fibrosis (CF) is often complicated by an allergic bronchopulmonary aspergillosis (ABPA), the authors hypothesised that SP-D may also be increased in serum during an ABPA, potentially assisting in its diagnosis and follow-up. In 22 patients with CF (11 with ABPA, 11 matched without ABPA) and 19 control patients without a pulmonary disease, SP-D concentrations in serum were assessed by an enzyme immunoassay. Serum SP-D in CF patients (130 +/- 16 ng x mL(-1) (mean +/- SEM)) was significantly higher than in the controls without lung disease (66 +/- 8 ng x mL(-1)). During the whole ABPA-episode, SP-D level did not change significantly, despite large changes of total serum immunoglobulin E. There was a clear negative correlation between SP-D concentration and overall lung function, i.e. forced expiratory volume in one second and forced vital capacity. Serum level of surfactant protein D may be of value to follow pulmonary function and lung injury in cystic fibrosis patients. Surfactant protein D serum levels are not helpful for the diagnosis and follow-up of an allergic bronchopulmonary aspergillosis episode, contrary to what was expected from animal experiments.

Immunodiagnosis of ABPA

For the diagnosis of allergic aspergillosis demonstration of specific immune responses to allergens has been accepted as a significant paradigm. Elevated levels of total IgE and Aspergillus fumigatus specific IgE and IgG antibodies are important criteria for diagnosis of ABPA. Although reference antigens or standardized methods are not available, there are a number of relevant recombinant antigens, which have been isolated in recent years. Several techniques have been employed in the demonstration of specific antibodies against antigens of Aspergillus fumigatus in the sera of patients. Of these methods, the widely followed ones are ELISA, radioimmunoassay, Western blot, and agar gel double diffusion. Recently, semi-automated methods have been developed using recombinant allergens to detect circulating antibody against Aspergillus. However, these methods have not been evaluated widely. Here we review the immunodiagnostic methods currently in use for allergic bronchopulmonary aspergillosis.

[Value of Aspergillus galactomannan antigen detection in the diagnosis and follow-up of invasive aspergillosis in hematological patients]

Serum galactomannan detection is considered to be a useful test for early diagnosis and follow-up of invasive aspergillosis. From February to September 2002, adult patients hospitalized in our Hematology Unit for receiving intensive chemotherapy and/or hematopoietic stem cell transplant were prospectively studied. We analyzed a total of 760 samples obtained from 100 patients. Eleven patients (11%) having a positive result (OD index >1.5 ng/ml) in two consecutive Platelia Aspergillus tests were considered galactomannan-positive cases. On the other hand, 12 patients (12%) were diagnosed of proven or probable invasive aspergillosis. Sensitivity (66.6%), specificity (95.5%), positive predictive value (72.7%) and negative predictive value (96.7%) were comparable to those of larger series. Galactomannan positivity allowed also to anticipate invasive aspergillosis diagnosis (from two to 17 days before radiographic findings and from two to 15 days before mycological culture). Moreover, kinetics of antigenemia could be useful for assessing therapeutic response. Once accepted galactomannan test as a diagnostic criterium for invasive aspergillosis knowing potential causes of false positive results is of paramount importance.

Does amphotericin B lipid complex (Abelcet) affect haematological parameters erroneously?

Abelcet is composed of large particles which could be misinterpreted as blood cells on measurements with blood cell counters. The direct measurement of drug suspensions on blood cell counters has been performed in an in vitro study. In an ex vivo study, the haematological parameters were compared before and during Abelcet infusions. A significant interference effect was observed in platelet counts, together with minimal differences in the WBC, RBC, and Hb parameters in the in vitro study. In the ex vivo study, there were statistically significant deviations only in RBC counts and in haemoglobin (Hb) level, while there was no difference in the other parameters. It is been reported that the drug accumulates very rapidly in the reticuloendothelial system and circulates minimally in the plasma. That is why there is a significant deviation in the direct counting of platelets, while the platelet counts taken from the patients do not differ statistically.

C-terminal cysteine residues determine the IgE binding of Aspergillus fumigatus allergen Asp f 2

The knowledge of the structure function relationship of the allergen is essential to design allergenic variants with reduced IgE binding capacity but intact T cell reactivity. Asp f 2 is a major allergen from the fungus Aspergillus fumigatus and >90% of A. fumigatus-sensitized individuals displayed IgE binding to Asp f 2. In the present study, we evaluated the involvement of C-terminal cysteine residues in IgE binding conformation of Asp f 2. The deletion mutants were constructed by adding three C-terminal cysteines of the native Asp f 2 one at a time to the non-IgE binding Asp f 2 (68-203). The point mutants of Asp f 2 (68-268) with C204A and C257A substitutions were constructed to study the role of C-terminal cysteines in IgE binding. Immunological evaluation of reduced and alkylated Asp f 2 and its mutants were conducted to determine the contribution of free sulfhydryl groups as well as the disulfide bonds in allergen Ab interaction. Four-fold increase in IgE Ab binding of Asp f 2 (68-267) compared with Asp f 2 (68-266) and complete loss in IgE binding of C204A mutant of Asp f 2 (68-268) indicate the involvement of C(204) and C(267) in IgE binding conformation of Asp f 2. A significant reduction in IgE binding of wild and mutated Asp f 2 after reduction and alkylation emphasizes the importance of cysteine disulfide bonds in epitope Ab interaction. The hypoallergenic variants may be explored further to develop safe immunotherapeutic strategy for allergic disorders.

Evaluation of allergic bronchopulmonary aspergillosis in patients with and without central bronchiectasis

Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity disorder induced by Aspergillus species colonizing the bronchial tree. Thirty one patients fulfilling criteria of ABPA were evaluated in the present study. Eleven patients were diagnosed as ABPA-S (serological positive) and 20 patients as ABPA-CB (with central bronchiectasis). The two groups of patients were compared on the basis of clinical, serological, and radiographic observations. Serum anti Aspergillus fumigatus IgG was positive in 72% of cases of ABPA-S and 85% of ABPA-CB patients at the time of presentation. Specific IgE against A. fumigatus and total IgE were significantly lower in ABPA-S (specific IgE= 7.42 IU and total IgE= 1127 ng/mL) as compared to ABPA-CB (specific IgE = 44 IU and total IgE = 2874 ng/mL). The spirometric changes in ABPA-S (normal 80%, mild obstruction 10%, and severe obstruction 10%) were milder than in ABPA-CB (normal 40%, mild obstruction 10%, moderate obstruction 20%, and severe obstruction 30%). These patients were monitored closely for seasonal exacerbation with new pulmonary infiltrates which gave lower recordings in ABPA-S patients. No patient in the ABPA-S group progressed to end-stage lung disease. This may be due to early recognition and treatment. The present data suggest that ABPA-S represents the early stage of an apparently less aggressive form of ABPA than ABPA-CB.

Surveillance of Aspergillus galactomannan antigenemia for invasive aspergillosis by enzyme-linked immunosorbent assay in neutropenic patients treated for hematological malignancies

INTRODUCTION

The incidence of invasive fungal infections is increasing in patients with hematological malignancies. Invasive aspergillosis is one of the most frequently encountered infections with a high mortality rate. New diagnostic tests for invasive aspergillosis such as the detection of Aspergillus galactomannan antigen by a sandwich enzyme-linked immunosorbent assay (ELISA) have recently been described. The objective of this study was to evaluate this assay as a potential surrogate for invasive procedures used to diagnose IA.

MATERIALS AND METHODS

We analyzed the performance of a commercially available ELISA test which we routinely use for the surveillance of galactomannan antigenemia in patients with hematological malignancies experiencing chemotherapy-induced prolonged neutropenia (ANC < 500/mm(3) for more than 7 days). Serum samples were collected on a weekly basis. Test positivity was defined in accordance with the manufacturer's recommendations.

RESULTS

Over the 2 year study period, we analyzed 507 samples obtained during 193 neutropenic episodes from 135 patients. Ten, six and two patients were considered to have proven, probable or possible invasive aspergillosis, respectively, based on clinical, radiological or microbiological data. Forty-four positive (Index>1.5) and 26 'undetermined' (1.5 > Index > 1.0) test results were observed in 17 and ten patients respectively. All invasive aspergillosis cases had at least a positive or an undetermined test result. Only one positive and one undetermined result were found in two patients before the onset of clinical or radiological signs suggesting invasive aspergillosis. Sensitivity was 69% and specificity 96% if only positive results are considered; when 'undetermined' test results were combined with positive results, sensitivity attained 100% and specificity 92% suggesting that the cutoff value for positivity can be lowered from 1.5 to 1.0.

CONCLUSIONS

Although the ELISA test did not appear to play a role in the early diagnosis of invasive aspergillosis and in the anticipation of antifungal therapy in our experience, it clarifies the diagnosis of infection in probable or possible invasive aspergillosis especially when the cutoff value is lowered and is useful for monitoring patients receiving specific therapy.

T-cell receptor bias in patients with allergic bronchopulmonary aspergillosis

CD4(+) Th2 helper cell mediated immune responses have been shown to play a crucial role in the pathogenesis of ABPA. HLA and TCR are the candidate genes, which can influence the specificity of these responses. We have previously established a strong association of HLA DR2/5 in ABPA susceptibility. The study was designed to determine whether allergen specific T cell express a limited usage of T cell receptor (TCR) Vbeta gene repertoire in ABPA and to find an association of susceptible HLA-DR determinants with the identified TCR gene segments. TCR Vbeta typing was performed on antigen specific T cell lines from 14 ABPA and 12 nonABPA patients. The majority of ABPA patients (86%) expressed allergen specific T cells with Vbeta13 genes indicating its role in susceptibility, whereas in nonABPA controls, Vbeta1 genes T cell repertoires were predominantly expressed. The unrestricted pattern of Vbeta gene amplification seen before antigen stimulation suggests an oligoclonal expansion of a specific T cell population in response to the allergen Asp f 1 in ABPA and nonABPA patients. The increased usage of Vbeta13 in ABPA and Vbeta1 in nonABPA indicates their importance in susceptibility and resistance, respectively.

Cyclophilins, a new family of cross-reactive allergens

Type I allergic reactions occur by immediate release of anaphylactogenic mediators due to cross-linking of IgE bound to the high-affinity Fc(epsilon)RI on the surface of effector cells of sensitized individuals after allergen exposure. IgE-mediated hypersensitivity against normally innocuous environmental antigens is of clinical importance because of an increasing incidence of asthma and severe atopic diseases causing raising health care burdens to the society. A vast variety of different molecular structures has been shown to be able to induce hypersensitivity reactions. However, the high structural homology between phylogenetically conserved allergenic proteins present in different, apparently unrelated sources of exposure seems to play an important role in IgE-mediated poly-sensitization. These allergen families, formally termed pan-allergens, represent proteins sharing a high degree of sequence homology. Here we report cloning, production and serological investigations of a new pan-allergen family, the cyclophilins, found to be cross-reactive across species including humans. IgE-mediated cross-reactivity against autoantigens may contribute to perpetuation of severe atopic disorders even in the absence of exogenous allergen exposure. The molecular definition of pan-allergen families may substantially contribute to reduce the number of structures needed for diagnosis and therapy of allergic diseases based on highly pure, standardized recombinant allergens.

Antibody binding of deletion mutants of Asp f 2, the major Aspergillus fumigatus allergen

Asp f 2, a 268 amino acid major allergen from Aspergillus fumigatus (Af) demonstrated nine linear IgE binding regions. It is not known whether any of these linear epitopes are also conformatory epitopes. Hence, we constructed deletion mutants of Asp f 2 devoid of one or more epitopes, and the IgE binding of these proteins with sera from patients with ABPA was compared with the full-length Asp f 2 expressed in E. coli and Pichia. The Pichia expressed protein reacted weakly with IgE, but strongly with IgG of ABPA sera compared to E. coli expressed Asp f 2. Weak IgE binding only was seen when the C-terminal or N-terminal was deleted, while depletion of both ends negated all reactivity. The monoclonal antibody IL-B8 and IgE and IgG of ABPA sera bound significantly to the Asp f 2 E-4 fragment indicating that the major B-cell epitope is located at the N-terminal end of Asp f 2.

Skin test reactivity to 2 recombinant Aspergillus fumigatus allergens in A fumigatus-sensitized asthmatic subjects allows diagnostic separation of allergic bronchopulmonary aspergillosis from fungal sensitization

BACKGROUND

Aspergillus fumigatus, an opportunistic pathogen, is associated with an impressive list of pulmonary complications. Among these, allergic bronchopulmonary aspergillosis (ABPA) represents a complex clinical syndrome that is difficult to diagnose. A clear distinction between allergic sensitization to A fumigatus and ABPA is essential for therapy to prevent deterioration of pulmonary function in subjects with ABPA.

OBJECTIVE

This study was carried out to determine the specificity and sensitivity of 2 A fumigatus allergens for the in vivo diagnosis of ABPA.

METHODS

Serologic investigations with recombinant A fumigatus allergens indicated the existence of disease-specific allergens that are useful for discrimination between ABPA and fungal sensitization. However, serologic studies fail to indicate the allergen-specific IgE levels required to elicit an allergic reaction in vivo.

RESULTS

We show that the recombinant A fumigatus allergens rAsp f 4, a protein with unknown biologic function, and rAsp f 6 (manganese superoxide dismutase) are able to provoke immediate skin reactions exclusively in patients with ABPA. The reactions, which are elicited by a few nonograms of the allergens, strictly depend on the presence of allergen-specific serum IgE. The IgE cut-off values for positive skin reactions to rAsp f 4 and rAsp f 6 of 0.9 and 1.2 kU(A)/L correspond to allergen-specific serum concentrations of 2 to 3 microg/L and allow a sensitive, highly specific diagnosis of ABPA.

CONCLUSIONS

In contrast to fungal extracts, rAsp f 4 and rAsp f 6 allow discrimination between ABPA and sensitization to A fumigatus. Moreover, the allergens are suitable for an automated serologic diagnosis of ABPA, facilitating their introduction in clinical practice.

Immunological characterization of Asp f 2, a major allergen from Aspergillus fumigatus associated with allergic bronchopulmonary aspergillosis

The 37-kDa recombinant protein Asp f 2, encoding an allergen of Aspergillus fumigatus, was expressed in a prokaryotic expression system and immunologically evaluated for its functional and structural properties. The open reading frame for a 310-amino-acid-long protein was shown to encode a signal peptide of 31 amino acids. A native 37-kDa culture filtrate protein and a 55-kDa mycelial glycoprotein (gp55) exhibited complete N-terminal sequence homology to Asp f 2. A GenBank search for homologous proteins revealed 60 and 44% sequence homologies to the cytosolic protein ASPND1 from Aspergillus nidulans and fibrinogen binding protein from Candida albicans, respectively. The glycosylation sites and cysteine molecules are conserved in all the three proteins. The extracellular matrix protein laminin showed a dose-dependent interaction with Asp f 2. This protein, expressed as a major cell-associated protein within 24 h of in vitro fungal culture, comprises 20 to 40% of total fungal protein. Furthermore, both native and recombinant Asp f 2 exhibited specific immunoglobulin (IgE) binding with allergic bronchopulmonary aspergillosis (ABPA) and cystic fibrosis-ABPA patients, whereas A. fumigatus-sensitized allergic asthma and normal control subjects failed to show IgE binding with Asp f 2. These results indicate that Asp f 2 is a major allergen of A. fumigatus exhibiting IgE antibody binding with sera from patients with ABPA. The antigen should be explored further for its potential role in the differential diagnosis of A. fumigatus-associated allergic diseases.

Effects of alkaline protease or restrictocin deficient mutants of Aspergillus fumigatus on human polymorphonuclear leukocytes

Several substances including proteases and restrictocin have been suggested as candidates for virulence determinants in invasive pulmonary aspergillosis. However, the roles of such substances are not well understood. This study compared the in vitro suppressive effects of Aspergillus fumigatus culture filtrates (ACFs), on the functions of human polymorphonuclear leukocytes (PMNLs), the principal cells in the host defence against aspergillus hyphae, from a clinically isolated wild-type and isogenic mutant strains which lack production of elastolytic alkaline protease (Alp) and/or restrictocin. ACFs were obtained by culturing conidia of each strain in Medium- 199 at 37 degrees C for 5 days. ACFs of the wild-type significantly (p<0.01) suppressed chemotaxis, superoxide anion (O2-) release and PMNL-mediated hyphal damage, compared with the control (Medium-199). ACFs of the mutant strains that lack Alp or restrictocin significantly (p<0.01) suppressed chemotaxis and O2(-)-release, but did not suppress hyphal damage, compared with the control. The wild-type significantly (p<0.01) suppressed chemotaxis of PMNLs compared with the mutant strains lacking Alp or restrictocin, whereas there were no significant differences in suppression of O2(-)-release and hyphal damage by PMNLs. ACF of a mutant strain that lacks both Alp and restrictocin had much less activity, but significantly (p<0.01) suppressed chemotaxis of PMNLs compared with the control. In conclusion, alkaline protease and restrictocin may play roles in the suppressive effect of Aspergillus fumigatus culture filtrates on the functions of human polymorphonuclear leukocytes. Other antiphagocytic substances produced by Aspergillus fumigatus remain to be identified.

The association of HLA-DR alleles and T cell activation with allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity lung disease caused by the mold Aspergillus fumigatus. We previously reported that the majority of T cell clones (TCC) isolated from three ABPA patients, and specific for a dominant Ag of A. fumigatus, Asp f 1, were IL-4-producing CD4+ Th2 cells capable of responding to Ag in association with the HLA-DR subtypes DRB1*1501, *1503, and *1601 for HLA-DR2, and DRB1*1101, *1104, and *1202 for HLA-DR5. In the present study we extended the previous findings to determine whether the observed restriction with the HLA-DR2/5 subtypes held importance in a larger patient population. Serotyping revealed that 16 of 18 ABPA patients were either HLA-DR2, HLA-DR5, or both. Compared with a normal control population, the frequencies of HLA-DR2 (50 vs 22.3%) and HLA-DR5 (44.4 vs 19.8%) were significantly increased in these ABPA patients. Genotype analyses of an additional 15 patients identified the same HLA-DR subtypes previously shown functional for Asp f 1 Ag presentation. The relative avidities of Asp f 1 peptides for the purified HLA-DR subtypes, DRB1*1501 (functional) and DRB1*1502 (nonfunctional), were examined to determine whether differential binding to the HLA-DR subtypes explains successful Ag presentation. Similar low binding avidities were detected for both HLA-DR subtypes, indicating that the functionality cannot be simply explained by differences in binding affinities. Thus, the limited number and their role in Ag presentation emphasizes the possibility that the six identified HLA-DR subtypes are important in the pathophysiology of ABPA.

Purification and characterization of a 93 kDa Aspergillus fumigatus antigen with diagnostic potential

A glycoprotein with an apparent molecular weight of 93 kDa was purified from a water-soluble extract of Aspergillus fumigatus NCPF 2109 by single step affinity chromatography using the mannose-specific snowdrop (Galanthus nivalis) lectin coupled to agarose. The carbohydrate moiety contained only mannose and galactose. Partial sequencing of cyanogen bromide fragments of the antigen yielded two sequences, KQNKP and GEIPMKF?PQL, with no homology to any reported proteins. In a preliminary evaluation of its diagnostic potential the 93 kDa antigen was recognized by the sera of four patients with allergic bronchopulmonary aspergillosis, in addition to a monoclonal antibody raised against a partially purified fraction of the A. fumigatus water-soluble extract.

Molecular cloning and expression of a recombinant Aspergillus fumigatus protein Asp f II with significant immunoglobulin E reactivity in allergic bronchopulmonary aspergillosis

The cDNA of Aspergillus fumigatus encoding an allergen was cloned and expressed in Escherichia coli. The 987 bp long cDNA clone expressed a recombinant protein Asp f II of 34 kd. This protein exhibited binding to immunoglobulin E (IgE) in the serum samples from patients with allergic bronchopulmonary aspergillosis (ABPA). The patients with ABPA and central bronchiectasis demonstrated high levels of serum IgE antibodies, whereas patients with ABPA without central bronchiectasis, patients with asthma and Aspergillus skin test reactivity but no evidence of ABPA, and patients with aspergilloma showed only low levels of IgE antibody to Asp f II. In two-dimensional electrophoresis, a native antigen electroeluted from an A. fumigatus culture filtrate antigen preparation showed an isoelectric point and molecular weight similar to that of Asp f II. In a competitive enzyme-linked immunosorbent assay (ELISA), the IgE antibody reactivity of Asp f II with patient serum samples could be significantly inhibited by culture filtrate antigens of A. fumigatus. These results indicate that Asp f II has immunologic reactivities comparable to those of native A. fumigatus antigens. The recombinant Asp f II can be expressed in E. coli in large quantities and should prove useful as a standardized allergen for sensitive and specific immunodiagnosis of ABPA, especially in patients with central bronchiectasis.

Evaluation of the diagnostic value of the measurement of (1-->3)-beta-D-glucan in patients with pulmonary aspergillosis

The value of the measurement of (1-->3)-beta-D-glucan, a major and common cell wall constituent of fungi, for diagnosing pulmonary aspergillosis was assessed in comparison with that of conventional examinations. The concentrations of (1-->3)-beta-D-glucan in sera was elevated in 7 out of 8 patients with active aspergillosis, but not in cases without active diseases, except for one sample. Further, the concentrations well reflected the activity of the aspergillosis in each case. Regarding conventional examinations, with the immunodiffusion test it was difficult to detect the present activity of the disease. The radioallergosorbent test was useful for diagnosing bronchopulmonary aspergillosis, but not for other types of aspergillosis. The Aspergillus-specific component, galactomannan, was insensitive and the enzyme-linked immunosorbent assay gave highly variable results. Thus, although the assessment of the specificity of the assay is still necessary, compared with other tests, the assay of (1-->3)-beta-D-glucan has the advantage of diagnosing pulmonary aspergillosis and also of assessing the disease activity.

Soluble serum interleukin 2 receptors in patients with asthma and allergic bronchopulmonary aspergillosis

BACKGROUND

When T cells are activated, they produce two distinct surface receptors for interleukin 2 (IL2). One of these surface receptors is a 55-kD protein called IL2Ra which is released into peripheral blood following T cell activation. This soluble protein (sIL2R) can be measured in peripheral blood utilizing an ELISA, and thus provides an indirect indicator of T cell activation.

OBJECTIVE

The purpose of this study was to determine whether allergic bronchopulmonary aspergillosis (ABPA) was associated with increased soluble interleukin 2 receptors (sIL2R).

METHODS

We used the Immunoenzymometric Assay Kit (Immunotech International, Marseille, France) which had a monoclonal antibody to sIL2R to sensitize wells. To determine the degree of T cell activation in patients with asthma and ABPA, we have evaluated the concentration of sIL2R in the peripheral blood in four groups: (1) 26 nonatopic patients, (2) 39 patients skin test positive to Aspergillus who did not have serologic evidence of ABPA, (3) 14 patients with quiescent ABPA, and (4) 13 patients who had a new roentgenographic infiltrate from ABPA.

RESULTS

The mean concentration of sIL2R in the four groups were 24.5 pM (+/- 16.7), 38.4 pM (+/- 27.2), 48.4 pM (+/- 28.2), and 64.8 pM (+/- 33.0), respectively. Group 4 was greater than groups 1 and 2 (P < .05), and group 3 was greater than group 1 (P < .05).

CONCLUSIONS

In patients with ABPA that is flaring, there is greater T cell activation than in either nonatopic controls or in patients who have asthma. Patients with ABPA in remission also had significantly greater T cell activation than nonatopic controls.

Allergic bronchopulmonary aspergillosis: serologic update for 1995

Allergic bronchopulmonary aspergillosis (ABPA) is a complex disease occurring in 1-2% of patients with asthma involving hypersensitivity to Aspergillus species. The diagnosis is made correlating clinical history and supporting serologic tests. Over many years various serologic tests have been used to both diagnose and follow disease activity. Initial serology from patients with all four positive tests (total serum IgE, IgE and IgG antibody indices, serum precipitins to Aspergillus fumigatus) were compared with the patients' most recent serology. The total serum IgE, IgE antibody index and serum precipitins had the most initial positive tests which stayed positive throughout treatment. The IgG antibody index was the most inconsistent. There were no significant differences between all four tests. We concluded that all four serologic tests are important in the diagnosis of ABPA.

IgE and eosinophil regulation in a murine model of allergic aspergillosis

Exposure of BALB/c mice to Aspergillus fumigatus (Af), the antigen responsible for causing allergic bronchopulmonary aspergillosis in humans, caused elevated levels of serum immunoglobulin E (IgE) and peripheral blood and lung eosinophilia similar to that observed in the human disease. We have investigated the role of interleukin-4 (IL-4), IL-5 and interferon-gamma in regulating IgE and eosinophilia in the mouse model. Animals were immunized by intraperitoneal injections of soluble Af antigens adsorbed to alum. These animals developed elevated IgE and Af specific IgG1 and were then treated with anticytokine monoclonal antibodies before the final exposure to particulate Af antigens by the intranasal route. The results showed that anti-IL-5 abrogated eosinophilia in mice, while those treated with anti-IL-4 retained the same or reduced IgE levels compared to pretreatment levels. All anti-IL-5, anti-IFN-gamma, and control antibody-treated animals showed enhanced IgE levels. Anti-IFN-gamma treatment of mice resulted in marked enhancement of eosinophilia compared to all other groups. Eosinophil numbers observed in the histological sections of the lungs confirmed the eosinophilia detected in the peripheral blood. These results indicate that the increase in IgE and eosinophils after exposure to Af antigens in BALB/c mice are due to Af-induced production of IL-4 and IL-5 and that both IgE and eosinophilia are independently regulated.

Rise in total IgE as an indicator of allergic bronchopulmonary aspergillosis in cystic fibrosis

BACKGROUND

Allergic bronchopulmonary aspergillosis is a serious complication of cystic fibrosis and may be difficult to diagnose. The aim of this study was to define the usefulness of measuring total IgE compared with other major criteria in the diagnosis of allergic bronchopulmonary aspergillosis in children with cystic fibrosis.

METHODS

A retrospective analysis was carried out of the case records of 160 children attending a tertiary referral paediatric cystic fibrosis clinic.

RESULTS

Sixteen children had a total IgE level above 500 IU/ml. Eleven children had six or more other major criteria and were considered to have allergic bronchopulmonary aspergillosis. These 11 children had a fourfold rise in IgE in association with clinical deterioration. A further child had a fourfold rise in IgE to 341 IU/l, and was also thought to have allergic bronchopulmonary aspergillosis. Eleven had a fall in IgE with successful treatment; one patient died with uncontrolled disease. Only one of these 12 children had negative precipitins to Aspergillus fumigatus. The five children with a raised IgE not thought to have bronchopulmonary aspergillosis had four or fewer major criteria and were not treated; none had positive precipitins.

CONCLUSIONS

A fourfold rise in total IgE, particularly to above 500 IU/ml, is strongly suggestive of the diagnosis of allergic bronchopulmonary aspergillosis in children with cystic fibrosis. The measurement of total IgE has the merit of being simple to perform and objective. Positive aspergillus precipitins provide useful confirmatory evidence. These two criteria, taken in conjunction with clinical deterioration and new radiological shadowing, allow simplification of the diagnosis of allergic bronchopulmonary aspergillosis in cystic fibrosis.

Isolation and characterization of a major allergenic component (gp55) of Aspergillus fumigatus

IgE class antibodies specific for antigens in a water-soluble extract of Aspergillus fumigatus (strain NHL-5759) were analyzed by immunoblotting with sera from patients with allergic bronchopulmonary aspergillosis. All the sera tested were reactive with a major 50 to 60 kd protein in the extract. This allergen, designated gp55, was purified by gel filtration and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The antigen was found to be present in the water-soluble extract in the form of a complex composed of approximately eight molecules of gp55. The carbohydrate and phosphate content of the purified antigen were 23.1% and 0.46%, respectively. The molar ratio of mannose to galactose residues was 2.76:1, and the protein was glycosylated predominantly with N-linked oligosaccharides. The serologic activity of the gp55 antigen was abolished by treatment with nonspecific protease (Pronase) but not by treatment with sodium metaperiodate or endoglycosidases. Thus the major antigenic site of the glycoprotein is located within its peptide moiety. The antigen itself displayed no chymotryptic or tryptic activity. The amino acid sequence of the 20 N-terminal residues of the antigen (ATPHEPVFFSWDAGAVTSFP) is different from that of any other protein previously reported.

Serological findings in patients with allergic bronchopulmonary aspergillosis during remission

The concentrations of total IgG, complement C3 and circulating immune complexes (CIC) were studied in 15 patients with allergic bronchopulmonary aspergillosis (ABPA) during remission and compared with those of 10 matched controls. The concentrations of complement and circulating immune complexes were similar to those of the controls but 33% of patients with ABPA in remission still had circulating immune complexes, mainly of IgG. Even so, the concentrations of IgG were significantly higher in patients during remission compared to controls but were lower than those observed during the acute stage of ABPA.

Hypersensitivity pneumonitis resulting from Aspergillus fumigatus in a greenhouse

A 57-y-old female who had cultivated vegetables in a plastic greenhouse developed a case of hypersensitivity pneumonitis from Aspergillus fumigatus. This report exemplifies a potential hazard caused by a thermotolerant fungus, A. fumigatus, in a poorly constructed greenhouse.

Allergic bronchopulmonary aspergillosis in patients with and without evidence of bronchiectasis

Allergic bronchopulmonary aspergillosis (ABPA) may complicate 1% to 2% of all cases of chronic asthma. Twenty-eight patients fulfilling the diagnostic criteria for ABPA but without evidence of proximal bronchiectasis [ABPA-S (seropositive)] were identified over a 12-year period and classified by stage. The majority of patients were in remission but all had chronic asthma. Serum anti-Aspergillus fumigatus (Af) IgG was lower in ABPA-S (n = 28) versus ABPA-CB (central bronchiectasis) (n = 58) at the time of initial presentation (IgG-Af index 3.62 versus 7.80, t = 3.46, P < or = .001). Serum IgG1-Af was significantly lower in ABPA-S as compared with ABPA-CB (t = 2.37, P = .011), as was serum IgG2-Af (t = 1.91, P = .031) and serum IgG4-Af (t = 1.78, P = .041). There were trends toward lower concentrations of total serum IgE, serum anti-Af-IgE, and anti-Af-IgA in ABPA-S. Eleven patients with ABPA-S were evaluated closely for a total of 63 patient-years and only four exacerbations with pulmonary infiltrates were identified. No patient in either group was observed to progress to end-stage or irreversible lung disease when early recognition and treatment were instituted. We conclude that ABPA-S represents the earliest stage or apparently a less aggressive form of ABPA.

Serum precipitins in pulmonary aspergillosis: preliminary results

Definitive diagnosis of pulmonary aspergillosis is difficult to establish. Thus, confirmative evidence of active fungal aggression is imperative. In this study, an immunodiffusion test was carried out on 36 cases of pulmonary aspergillosis and two groups of subjects comprising 133 patients with non-fungal diseases and 134 healthy volunteers as controls. The test was positive in 92.3% of the patients with mycetoma, in 50% of the patients with allergic bronchopulmonary aspergillosis, and in 25% of the patients with invasive aspergillosis. Results were negative in all subjects in the two control groups. The findings indicate the efficacy of the test under study for supporting the diagnosis of pulmonary aspergillosis.

Evaluation of clinico-immunological parameters in pediatric ABPA patients

Allergic bronchopulmonary aspergillosis patients (ten in the age group 5-13) were studied with respect to clinical and immunodiagnostic tests. All the patients showed wheal and flare reaction with A. fumigatus antigens. Clinical features included bilateral infiltration and hilar lymphadenopathy. Eosinophilic count in these patients was observed to be in the range of 300-2500/mm3. Sera of six patients indicated precipitin reaction with A. fumigatus antigens. An elevated total serum IgE was noticed in all the patients. A. fumigatus specific IgG and IgE antibodies were increased in these patients. Optical density of the sera of all the patients against controls were observed to be in the range of (0.426 to 1.8 for IgG and 0.147 to 0.562 for IgE) by ELISA. Western blot analysis indicated that there may be correlation between the clinical stages of the disease and immunological reactivity of the sera with various antigenic components.

Pulmonary eosinophilia with and without allergic bronchopulmonary aspergillosis

Sixty five patients with pulmonary eosinophilia attending one respiratory unit were reviewed. All had fleeting radiographic abnormalities and peripheral blood eosinophil counts greater than 500 x 10(6)/l. Eighteen had a single episode and 47 recurrent episodes during a median follow up period of 14 years. Thirty three patients had allergic bronchopulmonary aspergillosis on the basis of a positive skin test response to Aspergillus fumigatus, serum precipitins, or culture of A fumigatus from sputum, or a combination of these. All but seven patients had asthma, six of the seven being in the group who did not have allergic bronchopulmonary aspergillosis. The patients with allergic bronchopulmonary aspergillosis were more often male and had a greater incidence of asthma and an earlier age of onset of asthma than those without aspergillosis. The patients with aspergillosis had lower mean blood eosinophil counts and more episodes of pulmonary eosinophilia and more commonly had radiographic shadowing that suggested fibrosis or bronchiectasis (20 v 7). Pulmonary eosinophilia associated with allergic bronchopulmonary aspergillosis appears to be a distinct clinical syndrome resulting in greater permanent radiographic abnormality despite lower peripheral blood eosinophil counts.

Murine monoclonal antibodies binding to the specific antigens of Aspergillus fumigatus associated with allergic bronchopulmonary aspergillosis

Four murine monoclonal antibodies, which were produced against Aspergillus fumigatus antigens using hybridoma technology, reacted with different antigenic components of A. fumigatus, and in turn these antigens showed reactivity with the sera from allergic bronchopulmonary aspergillosis (ABPA). All four antibodies were of IgM isotype. These antibodies reacted against eight antigen preparations from three different strains of A. fumigatus by enzyme-linked immunosorbent assay (ELISA). Only two of four antibodies reacted with the antigens in crossed immunoelectrophoresis (CIE), rocket immunoelectrophoresis, and agar gel double diffusion. In western blot analysis it was found that the antigenic components reacting with the monoclonal antibodies were mostly of the low molecular weight components of A. fumigatus antigens. These components also showed binding to both IgG and IgE antibodies in the sera of ABPA patients, but failed to show any reactivity with sera from aspergilloma patients. Hence these antigenic components may be of diagnostic significance and can be isolated using immunoaffinity chromatography.

Immune responses to Aspergillus in cystic fibrosis

Aspergillus fumigatus (Af) is well recognized in its ability to colonize the respiratory tract in cystic fibrosis (CF). Furthermore, a number of the immune responses of the patient with CF to this organism have been characterized, and the immune inflammatory response to Af may result in allergic bronchopulmonary aspergillosis (ABPA). This study evaluated a series of immunologic parameters in 75 patients with CF in order to characterize more fully the spectrum of immune responses of those patients to Af and to clarify the relationship of those responses to the clinical features of ABPA. The patients could be classified into four groups, depending on the clinical and immunologic findings. Eight (10.7%) of the 75 patients had clinical and laboratory evidence of ABPA, including immediate cutaneous reactivity to Af, eosinophilia, elevated total serum IgE, elevated serum IgE-Af or IgG-Af, and precipitating antibody to Af. Ten (13.3%) patients had these features, except that the total serum IgE level was within the normal range. Forty (53.5%) of the patients had no significant criteria for ABPA but had varying immunologic responses to Af, such as immediate cutaneous reactivity to Af in 25 patients and elevated serum IgE-Af and/or IgG-Af in 19 patients. Seventeen (22.7%) patients had no evidence of an immunologic response, as determined by skin testing and serologic assays. The study demonstrated that the response of patients with CF to Af ranges from clinically apparent ABPA to a possible variant of ABPA, to a nondiagnostic group of features consistent with sensitization to Af or to no characteristic immune response.

Partial characterization of a rapidly released antigenic/allergenic component (Ag 5) of Aspergillus fumigatus

An antigenic component of Aspergillus fumigatus, which was responsible for inducing an initial early antibody response in rabbits immunized with A. fumigatus germlings, has been identified and partially characterized. By immunofluorescent antibody and ELISA techniques, this antigen was demonstrated to be present on the germling surface, although it was also detected in supernatants of conidia/germlings within 1 hour and was present in all shake and stationary culture-filtrate extracts. By incorporation of a monospecific antiserum to this component in an intermediate gel of the reference self-crossed radioimmunoelectrophoresis pattern for allergic bronchopulmonary aspergillosis sera, it was recognized as Ag 5 and was also demonstrated to bind specific IgE. Further immunochemical analyses have revealed that Ag 5 is relatively heat labile, does not bind to concanavalin A, and has a molecular weight of approximately 35 kd. This rapidly released antigenic/allergenic component may play an important role in the initiation of immunologic responses in patients with allergic bronchopulmonary aspergillosis.