A pathologic study of allergic bronchopulmonary aspergillosis

Interplay of Cytokines and Chemokines in Aspergillosis

Aspergillosis is a fungal infection caused by various species of Aspergillus, most notably A. fumigatus. This fungus causes a spectrum of diseases, including allergic bronchopulmonary aspergillosis, aspergilloma, chronic pulmonary aspergillosis, and invasive aspergillosis. The clinical manifestations and severity of aspergillosis can vary depending on individual immune status and the specific species of Aspergillus involved. The recognition of Aspergillus involves pathogen-associated molecular patterns (PAMPs) such as glucan, galactomannan, mannose, and conidial surface proteins. These are recognized by the pathogen recognition receptors present on immune cells such as Toll-like receptors (TLR-1,2,3,4, etc.) and C-type lectins (Dectin-1 and Dectin-2). We discuss the roles of cytokines and pathogen recognition in aspergillosis from both the perspective of human and experimental infection. Several cytokines and chemokines have been implicated in the immune response to Aspergillus infection, including interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), CCR4, CCR17, and other interleukins. For example, allergic bronchopulmonary aspergillosis (ABPA) is characterized by Th2 and Th9 cell-type immunity and involves interleukin (IL)-4, IL-5, IL-13, and IL-10. In contrast, it has been observed that invasive aspergillosis involves Th1 and Th17 cell-type immunity via IFN-γ, IL-1, IL-6, and IL-17. These cytokines activate various immune cells and stimulate the production of other immune molecules, such as antimicrobial peptides and reactive oxygen species, which aid in the clearance of the fungal pathogen. Moreover, they help to initiate and coordinate the immune response, recruit immune cells to the site of infection, and promote clearance of the fungus. Insight into the host response from both human and animal studies may aid in understanding the immune response in aspergillosis, possibly leading to harnessing the power of cytokines or cytokine (receptor) antagonists and transforming them into precise immunotherapeutic strategies. This could advance personalized medicine.

Allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is an inflammatory disease caused by immunologic reactions initiated against Aspergillus fumigatus colonizing the airways of patients with asthma and cystic fibrosis. The common manifestations include treatment-resistant asthma, transient and fleeting pulmonary opacities and bronchiectasis. It is believed that globally there are about five million cases of ABPA, with India alone accounting for about 1.4 million cases. The occurrence of ABPA among asthmatic patients in special clinics may be as high as 13 per cent. Thus, a high degree of suspicion for ABPA should be entertained while treating a patient with bronchial asthma, particularly in specialized clinics. Early diagnosis and appropriate treatment can delay (or even prevent) the onset of bronchiectasis, which suggests that all patients of bronchial asthma should be screened for ABPA, especially in chest clinics. The current review summarizes the recent advances in the pathogenesis, diagnosis and management of ABPA.

Transcriptomic and proteomic host response to Aspergillus fumigatus conidia in an air-liquid interface model of human bronchial epithelium

Aspergillus fumigatus (A. fumigatus) is a wide-spread fungus that is a potent allergen in hypersensitive individuals but also an opportunistic pathogen in immunocompromised patients. It reproduces asexually by releasing airborne conidiospores (conidia). Upon inhalation, fungal conidia are capable of reaching the airway epithelial cells (AECs) in bronchial and alveolar tissues. Previous studies have predominantly used submerged monolayer cultures for studying this host-pathogen interaction; however, these cultures do not recapitulate the mucocililary differentiation phenotype of the in vivo epithelium in the respiratory tract. Thus, the aim of this study was to use well-differentiated primary human bronchial epithelial cells (HBECs) grown at the air-liquid interface (ALI) to determine their transcriptomic and proteomic responses following interaction with A. fumigatus conidia. We visualized conidial interaction with HBECs using confocal laser scanning microscopy (CLSM), and applied NanoString nCounter and shotgun proteomics to assess gene expression changes in the human cells upon interaction with A. fumigatus conidia. Western blot analysis was used to assess the expression of top three differentially expressed proteins, CALR, SET and NUCB2. CLSM showed that, unlike submerged monolayer cultures, well-differentiated ALI cultures of primary HBECs were estimated to internalize less than 1% of bound conidia. Nevertheless, transcriptomic and proteomic analyses revealed numerous differentially expressed host genes; these were enriched for pathways including apoptosis/autophagy, translation, unfolded protein response and cell cycle (up-regulated); complement and coagulation pathways, iron homeostasis, nonsense mediated decay and rRNA binding (down-regulated). CALR and SET were confirmed to be up-regulated in ALI cultures of primary HBECs upon exposure to A. fumigatus via western blot analysis. Therefore, using transcriptomics and proteomics approaches, ALI models recapitulating the bronchial epithelial barrier in the conductive zone of the respiratory tract can provide novel insights to the molecular response of bronchial epithelial cells upon exposure to A. fumigatus conidia.

Ecology of aspergillosis: insights into the pathogenic potency of Aspergillus fumigatus and some other Aspergillus species

Fungi of the genus Aspergillus are widespread in the environment. Some Aspergillus species, most commonly Aspergillus fumigatus, may lead to a variety of allergic reactions and life-threatening systemic infections in humans. Invasive aspergillosis occurs primarily in patients with severe immunodeficiency, and has dramatically increased in recent years. There are several factors at play that contribute to aspergillosis, including both fungus and host-related factors such as strain virulence and host pulmonary structure/immune status, respectively. The environmental tenacity of Aspergilllus, its dominance in diverse microbial communities/habitats, and its ability to navigate the ecophysiological and biophysical challenges of host infection are attributable, in large part, to a robust stress-tolerance biology and exceptional capacity to generate cell-available energy. Aspects of its stress metabolism, ecology, interactions with diverse animal hosts, clinical presentations and treatment regimens have been well-studied over the past years. Here, we synthesize these findings in relation to the way in which some Aspergillus species have become successful opportunistic pathogens of human- and other animal hosts. We focus on the biophysical capabilities of Aspergillus pathogens, key aspects of their ecophysiology and the flexibility to undergo a sexual cycle or form cryptic species. Additionally, recent advances in diagnosis of the disease are discussed as well as implications in relation to questions that have yet to be resolved.

Pattern recognition pathways leading to a Th2 cytokine bias in allergic bronchopulmonary aspergillosis patients

BACKGROUND

Allergic bronchopulmonary aspergillosis (ABPA) is characterised by an exaggerated Th2 response to Aspergillus fumigatus, but the immunological pathways responsible for this effect are unknown.

OBJECTIVE

The aim of this study was to decipher the pattern recognition receptors (PRRs) and cytokines involved in the Aspergillus-specific Th2 response and to study Aspergillus-induced responses in healthy controls and ABPA patients.

METHODS

Peripheral blood mononuclear cells (PBMCs) were stimulated with heat-killed Aspergillus conidia, various other pathogens, or PRR ligands. PRRs and cytokine pathways were blocked with PRR-blocking reagents, anti-TNF (Etanercept or Adalimumab), IL-1Ra (Anakinra) or IFNγ (IFN-gamma). ELISA and FACS were used to analyse cytokine responses.

RESULTS

Aspergillus was the only pathogen that stimulated the Th2 cytokines IL-5 and IL-13, while Gram-negative bacteria, Gram-positive bacteria, Candida albicans, chitin, β-glucan or Toll-like receptor (TLR) ligands did not. Depletion of CD4(+) cells abolished IL-13 production. Blocking complement receptor 3 (CR3) significantly reduced IL-5 and IL-13, while blocking TLR2, TLR4 or dectin-1 had no effect. ABPA patients displayed increased Aspergillus-induced IL-5 and IL-13 and decreased IFNγ production compared with healthy controls. All biological agents tested showed the capability to inhibit Th2 responses, but also decreased Aspergillus-induced IFNγ.

CONCLUSIONS AND CLINICAL RELEVANCE

Aspergillus conidia are unique in triggering Th2 responses in human PBMCs, through a CR3-dependent pathway. ABPA patients display a significantly increased Aspergillus-induced Th2/Th1 ratio that can be modulated by biologicals. These data provide a rationale to explore IFNγ therapy in ABPA as a corticosteroid-sparing treatment option, by dampening Th2 responses and supplementing the IFNγ deficiency at the same time.

The immune interplay between the host and the pathogen in Aspergillus fumigatus lung infection

The interplay between Aspergillus fumigatus and the host immune response in lung infection has been subject of studies over the last years due to its importance in immunocompromised patients. The multifactorial virulence factors of A. fumigatus are related to the fungus biological characteristics, for example, structure, ability to grow and adapt to high temperatures and stress conditions, besides capability of evading the immune system and causing damage to the host. In this context, the fungus recognition by the host innate immunity occurs when the pathogen disrupts the natural and chemical barriers followed by the activation of acquired immunity. It seems clear that a Th1 response has a protective role, whereas Th2 reactions are often associated with higher fungal burden, and Th17 response is still controversial. Furthermore, a fine regulation of the effector immunity is required to avoid excessive tissue damage associated with fungal clearance, and this role could be attributed to regulatory T cells. Finally, in this work we reviewed the aspects involved in the complex interplay between the host immune response and the pathogen virulence factors, highlighting the immunological issues and the importance of its better understanding to the development of novel therapeutic approaches for invasive lung aspergillosis.

Allergic bronchopulmonary mycosis due to fungi other than Aspergillus: a global overview

Allergic bronchopulmonary mycosis (ABPM) is a hypersensitivity-mediated disease of worldwide distribution. We reviewed 143 reported global cases of ABPM due to fungi other than aspergilli. The commonest etiologic agent was Candida albicans, reported in 60% of the cases, followed by Bipolaris species (13%), Schizophyllum commune (11%), Curvularia species (8%), Pseudallescheria boydii species complex (3%) and rarely, Alternaria alternata, Fusarium vasinfectum, Penicillium species, Cladosporium cladosporioides, Stemphylium languinosum, Rhizopus oryzae, C. glabrata, Saccharomyces cerevisiae and Trichosporon beigelii. India accounted for about 47% of the globally reported cases of ABPM, attributed predominantly to C. albicans, followed by Japan (16%) where S. commune predominates, and the remaining one-third from the USA, Australia and Europe. Notably, bronchial asthma was present in only 32% of ABPM cases whereas its association with development of allergic bronchopulmonary aspergillosis (ABPA) is known to be much more frequent. The cases reviewed herein revealed a median IgE value threefold higher than that of ABPA, suggesting that the etiologic agents of ABPM incite a stronger immunological response than that by aspergilli in ABPA. ABPM is currently underdiagnosed, warranting comprehensive basic and clinical studies in order to elucidate its epidemiology and to devise a more effective therapy.

Eosinophilic pneumonias

This review starts with discussions of several infectious causes of eosinophilic pneumonia, which are almost exclusively parasitic in nature. Pulmonary infections due specifically to Ascaris, hookworms, Strongyloides, Paragonimus, filariasis, and Toxocara are considered in detail. The discussion then moves to noninfectious causes of eosinophilic pulmonary infiltration, including allergic sensitization to Aspergillus, acute and chronic eosinophilic pneumonias, Churg-Strauss syndrome, hypereosinophilic syndromes, and pulmonary eosinophilia due to exposure to specific medications or toxins.

Management of allergic bronchopulmonary aspergillosis: a review and update

Since the first description of allergic bronchopulmonary aspergillosis (ABPA) in the 1950s there have been numerous studies that have shed light on the characteristics and immunopathogenesis of this disease. The increased knowledge and awareness have resulted in earlier diagnosis and treatment of patients with this condition. This article aims to provide a summary and updates on ABPA by reviewing the results of recent studies on this disease with a focus on articles published within the last 5 years. A systematic search of PubMed/Medline with keywords of ABPA or allergic bronchopulmonary aspergillosis was performed. All selected articles were reviewed with a focus on findings of articles published from December 2006 to December 2011. The relevant findings are summarized in this paper.

Immunopathology and immunogenetics of allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is a Th2 hypersensitivity lung disease in response to Aspergillus fumigatus that affects asthmatic and cystic fibrosis (CF) patients. Sensitization to A. fumigatus is common in both atopic asthmatic and CF patients, yet only 1%–2% of asthmatic and 7%–9% of CF patients develop ABPA. ABPA is characterized by wheezing and pulmonary infiltrates which may lead to pulmonary fibrosis and/or bronchiectasis. The inflammatory response is characterized by Th2 responses to Aspergillus allergens, increased serum IgE, and eosinophilia. A number of genetic risks have recently been identified in the development of ABPA. These include HLA-DR and HLA-DQ, IL-4 receptor alpha chain (IL-4RA) polymorphisms, IL-10 −1082GA promoter polymorphisms, surfactant protein A2 (SP-A2) polymorphisms, and cystic fibrosis transmembrane conductance regulator gene (CFTR) mutations. The studies indicate that ABPA patients are genetically at risk to develop skewed and heightened Th2 responses to A. fumigatus antigens. These genetic risk studies and their consequences of elevated biologic markers may aid in identifying asthmatic and CF patients who are at risk to the development of ABPA. Furthermore, these studies suggest that immune modulation with medications such as anti-IgE, anti-IL-4, and/or IL-13 monoclonal antibodies may be helpful in the treatment of ABPA.

Pulmonary aspergillosis: a clinical review

Aspergillus is a mould which may lead to a variety of infectious, allergic diseases depending on the host's immune status or pulmonary structure. Invasive pulmonary aspergillosis occurs primarily in patients with severe immunodeficiency. The significance of this infection has dramatically increased with growing numbers of patients with impaired immune state associated with the management of malignancy, organ transplantation, autoimmune and inflammatory conditions; critically ill patients and those with chronic obstructive pulmonary disease appear to be at an increased risk. The introduction of new noninvasive tests, combined with more effective and better-tolerated antifungal agents, has resulted in lower mortality rates associated with this infection. Chronic necrotising aspergillosis is a locally invasive disease described in patients with chronic lung disease or mild immunodeficiency. Aspergilloma is usually found in patients with previously formed cavities in the lung, whereas allergic bronchopulmonary aspergillosis, a hypersensitivity reaction to Aspergillus antigens, is generally seen in patients with atopy, asthma or cystic fibrosis. This review provides an update on the evolving epidemiology and risk factors of the major manifestations of Aspergillus lung disease and the clinical manifestations that should prompt the clinician to consider these conditions. Current approaches for the diagnosis and management of these syndromes are discussed.

Allergic bronchopulmonary aspergillosis in asthma and cystic fibrosis

Allergic bronchopulmonary aspergillosis (ABPA) is a Th2 hypersensitivity lung disease in response to Aspergillus fumigatus that affects asthmatic and cystic fibrosis (CF) patients. Sensitization to A. fumigatus is common in both atopic asthmatic and CF patients, yet only 1-2% of asthmatic and 7-9% of CF patients develop ABPA. ABPA is characterized by wheezing and pulmonary infiltrates which may lead to pulmonary fibrosis and/or bronchiectasis. The inflammatory response is characterized by Th2 responses to Aspergillus allergens, increased serum IgE and eosinophilia. A number of genetic risks have recently been identified in the development of ABPA. These include HLA-DR and HLA-DQ, IL-4 receptor alpha chain (IL-4RA) polymorphisms, IL-10-1082GA promoter polymorphisms, surfactant protein A2 (SP-A2) polymorphisms, and cystic fibrosis transmembrane conductance regulator gene (CFTR) mutations. The studies indicate that ABPA patients are genetically at risk to develop skewed and heightened Th2 responses to A. fumigatus antigens. These genetic risk studies and their consequences of elevated biologic markers may aid in identifying asthmatic and CF patients who are at risk to the development of ABPA. Furthermore, these studies suggest that immune modulation with medications such as anti-IgE, anti-IL-4 and/or IL-13 monoclonal antibodies may be helpful in the treatment of ABPA.

Aspergillus hypersensitivity in patients with chronic obstructive pulmonary disease: COPD as a risk factor for ABPA?

Allergic bronchopulmonary aspergillosis (ABPA) is a pulmonary disorder caused by hypersensitivity to Aspergillus fumigatus which primarily complicates the course of asthma and cystic fibrosis. There is a theoretical possibility that patients with chronic obstructive pulmonary disease (COPD) can also develop Aspergillus hypersensitivity (AH) and/or ABPA. The aim of this prospective case-control study conducted in the Chest Clinic was to evaluate the prevalence of AH/ABPA in patients with COPD. Two hundred subjects with COPD (17, 62, 74, 47; GOLD guidelines stages I–IV respectively) and 100 healthy volunteers were screened with an Aspergillus skin test. Patients were said to have AH if they demonstrated immediate cutaneous hyperreactivity to A. fumigatus antigen and those with positive responses were further investigated for ABPA. Of this patient population there were 179 (89.5%) males and 21 (10.5%) females with a mean age of 57.1 in the COPD arm and 88 males and 12 females with a mean age of 52.3 in the control arm. AH was found in 17 (8.5%) patients with COPD as compared to none in the control group. Two (1.0%) COPD patients fulfilled the serologic criteria for the diagnosis of ABPA. On univariate analysis, age of the patient, duration of COPD, smoking index and the COPD severity did not predict the occurrence of AH. On the basis of this study we concluded that AH/ABPA can occur in patients with COPD, and it is probable that COPD could be a predisposing factor for AH/ABPA. The clinical significance of AH and ABPA in COPD remains unclear.

An alternate method of classifying allergic bronchopulmonary aspergillosis based on high-attenuation mucus

Background and Aim

Allergic bronchopulmonary aspergillosis (ABPA) is classified radiologically based on the findings of central bronchiectasis (CB) and other radiologic features (ORF). However, the long-term clinical significance of these classifications remains unknown. We hypothesized that the immunological activity and outcomes of ABPA could be predicted on HRCT chest finding of high-attenuation mucus (HAM), a marker of inflammatory activity. In this study, we evaluate the severity and clinical outcomes of ABPA with different radiological classifications.

Methods

Patients were classified based on CT chest findings as: (a) serologic ABPA (ABPA-S) and ABPA-CB; (b) ABPA-S, ABPA-CB, and ABPA-CB-ORF; and, (c) ABPA-S, ABPA-CB and ABPA-CB-HAM. The clinical, spirometric and serological (total and A fumigatus specific IgE levels, eosinophil count) severity of the disease and clinical outcomes in various classifications were analyzed.

Results

Of the 234 (123 males, 111 females; mean age, 34.1 years) patients, 55 (23.5%) had normal HRCT, 179 (76.5%) had CB, 49 (20.9%) had HAM, and 27 (11.5%) had ORF. All immunological markers were consistently higher in the HAM classification, while in other classifications these findings were inconsistent. On multivariate analysis, the factors predicting frequent relapses were presence of HAM (OR 7.38; 95% CI, 3.21–17.0) and CB (OR 3.93; 95% CI, 1.63–9.48) after adjusting for ORF.

Conclusions

The classification scheme based on HAM most consistently predicts immunological severity in ABPA. Central bronchiectasis and HAM are independent predictors of recurrent relapses in ABPA. Hence, HAM should be employed in the radiological classification of ABPA.

Noninvasive pulmonary Aspergillus infections

Aspergillus can cause several forms of pulmonary disease ranging from colonization to invasive aspergillosis and largely depends on the underlying lung and immune function of the host. This article reviews the clinical presentation, diagnosis, pathogenesis, and treatment of noninvasive forms of Aspergillus infection, including allergic bronchopulmonary aspergillosis (ABPA), aspergilloma, and chronic pulmonary aspergillosis (CPA). ABPA is caused by a hypersensitivity reaction to Aspergillus species and is most commonly seen in patients who have asthma or cystic fibrosis. Aspergillomas, or fungus balls, can develop in previous areas of cavitary lung disease, most commonly from tuberculosis. CPA has also been termed semi-invasive aspergillosis and usually occurs in patients who have underlying lung disease or mild immunosuppression.

Prevalence of allergic bronchopulmonary aspergillosis in patients with cystic fibrosis in the state of Bahia, Brazil

OBJECTIVE

To determine the prevalence of allergic bronchopulmonary aspergillosis (ABPA) in patients with cystic fibrosis treated at a referral center in the state of Bahia, Brazil.

METHODS

A cross-sectional study, with prospective data collection, carried out at the Cystic Fibrosis Referral Center of Bahia of the Octavio Mangabeira Specialized Hospital. We evaluated 74 patients diagnosed with cystic fibrosis, older than six years of age, treated between December 9, 2003 and March 7, 2005. We analyzed the following variables: gender, age, forced vital capacity, forced expiratory volume in one second, pharmacodynamic response, chest X-ray findings, facial sinus X-ray findings, wheezing, cultures for Aspergillus spp., total immunoglobulin E (IgE), specific IgE for Aspergillus fumigatus and immediate skin test reactivity to A.fumigatus antigen.

RESULTS

Of the 74 patients, 2 were diagnosed with ABPA. We found total IgE levels > 1,000 IU/mL in 17 (23%), positive immediate skin reactivity to A. fumigatus antigen in 19 (25.7%) and wheezing in 60 (81.1%).

CONCLUSIONS

The prevalence of ABPA was 2.7%. The high levels of total IgE, high incidence of wheezing and high rate of immediate skin test reactivity to A. fumigatus antigen suggest that these patients should be carefully monitored due to their propensity to develop ABPA.

Allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is an immunologic pulmonary disorder caused by hypersensitivity to Aspergillus fumigatus. Clinically, a patient presents with chronic asthma, recurrent pulmonary infiltrates, and bronchiectasis. The population prevalence of ABPA is not clearly known, but the prevalence in asthma clinics is reported to be around 13%. The disorder needs to be detected before bronchiectasis has developed because the occurrence of bronchiectasis is associated with poorer outcomes. Because many patients with ABPA may be minimally symptomatic or asymptomatic, a high index of suspicion for ABPA should be maintained while managing any patient with bronchial asthma whatever the severity or the level of control. This underscores the need for routine screening of all patients with asthma with an Aspergillus skin test. Finally, there is a need to update and revise the criteria for the diagnosis of ABPA. This review summarizes the advances in the diagnosis and management of ABPA using a systematic search methodology.

Usefulness of serum IgG4 in the diagnosis and follow up of autoimmune pancreatitis: A systematic literature review and meta-analysis

High circulating serum immunoglobulin G4 (IgG4) levels have been proposed as a marker of autoimmune pancreatitis (AIP). The aim of the present study was to review the data existing in the English literature on the usefulness of the IgG4 serum levels in the diagnosis and follow up of patients with AIP. A total of 159 patients with AIP and 1099 controls were described in seven selected papers reporting the usefulness of serum IgG4 in diagnosing AIP. In total, 304 controls had pancreatic cancer, 96 had autoimmune diseases, and the remaining 699 had other conditions. The summary receiver-operating characteristic curve analysis was carried out by means of Meta-DiSc open-access software. Serum IgG4 showed good accuracy in distinguishing between AIP and the overall controls, pancreatic cancer and other autoimmune diseases (area under the curve [+/- SE]: 0.920 +/- 0.073, 0.914 +/- 0.191, and 0.949 +/- 0.024, respectively). The studies analyzed showed significantly heterogeneous specificity values in each of the three analyses performed. The analysis of the four studies comparing AIP and pancreatic cancers also showed significantly heterogeneous values of sensitivities and odds ratios. Regarding the usefulness of IgG4 as a marker of efficacy of steroid treatment, a decrease in the serum concentrations of IgG4 was found in the four available studies. The serum IgG4 subclass is a good marker of AIP, and its determination should be included in the diagnostic workup of this disease. However, the heterogeneity of the studies published until now means that more studies are necessary in order to better evaluate the true accuracy of IgG4 in discriminating AIP versus other autoimmune diseases.

Interaction of airway epithelial cells (A549) with spores and mycelium of Aspergillus fumigatus

OBJECTIVE

To study the interaction of airway epithelial cell line A549 with fragments of mycelium, spores of Aspergillus fumigatus in vitro and to determine if toll-like receptors (TLRs) are involved in the process.

METHODS

A549 cells were exposed to fragments of A. fumigatus mycelium, zymosan and inactivated A. fumigatus spores. Interleukin 6 (IL-6) and IL-8 released by A549 cells to the culture supernatant were measured by ELISA. Presence of TLR2 and TLR4 on A549 cells were studied by immuno-histochemistry.

RESULTS

Mycelium fragments of A. fumigatus showed strong binding to epithelial cells but had limited effects on the release of IL-6 and IL-8 by A549 cells. Irradiated A. fumigatus spores were partly internalised by A549 cells and inhibited A549 cells to produce IL-6. TNF-alpha pre-incubated A549 cells produced increased IL-6 after exposure to zymosan and WIAF. Immuno-histochemistry showed a negative staining for TLR2 and TLR4.

CONCLUSIONS

The low levels of cytokines produced by A549 cells after the firm binding of either mycelium or spores of A. fumigatus may lead to insufficient recruitment of inflammatory cells to the infected site, which may result in the escape of detection by the immune defence system. TLR2 and TLR4 are probably not or only in part involved in the above process, although very low expression cannot be excluded.

Allergic bronchopulmonary aspergillosis in paediatric cystic fibrosis patients

Allergic bronchopulmonary aspergillosis (ABPA) is a severe complication in children, adolescents and adults with cystic fibrosis (CF), the prevalence of which ranges from 6-25%. The disease is the result of the colonisation of the respiratory tract by fungi of the genus Aspergillus, commonly Aspergillus fumigatus, and subsequent host sensitisation to fungal antigens, accompanied by a Th2 CD4 type response mediated by the production of specific IgE. The consequent inflammatory and obstructive bronchopulmonary injury can progress to fibrosis. The diagnosis should be considered early in patients with CF who show wheezing, transient pulmonary infiltrates and reduced lung function. The objective diagnosis is not straightforward because of overlapping clinical and radiological signs, particularly the progression of bronchiectasis. Specific criteria are needed for the diagnosis of ABPA in patients with CF, such as those proposed by the Cystic Fibrosis Foundation. The study of specific IgE against recombinant antigens of A. fumigatus has contributed to the early diagnosis of ABPA with high sensitivity and specificity. The technique has also shown promise in the follow-up of patients after steroid therapy and the early detection of recurrences. Treatment consists of long-term systemic corticosteroid usage, the monitoring of their adverse effects, and of the measurement of total serum IgE levels. The concomitant use of oral itraconazole seems to promote a better control of the disease and to reduce the duration of systemic steroid therapy but its use continues to be controversial. Controlled studies involving larger numbers of patients are necessary if we are to better understand the management of ABPA.

Genetic and respiratory tract risk factors for aspergillosis: ABPA and asthma with fungal sensitization

Allergic bronchopulmonary aspergillosis (ABPA) is a Th2 allergic hypersensitivity lung disease due to bronchial colonization of Aspergillus fumigatus that affects 1-2% of asthmatic and 7-9% of cystic fibrosis (CF) patients. We hypothesize that genetic risk factors predispose these patients to develop ABPA. We previously reported HLA-DR2 and DR5 restriction as a risk factor for the development of ABPA. We further propose that HLA-DR restriction is necessary but not sufficient for the development of ABPA. Recently, we reported that IL-4Rα single nucleotide polymorphisms (SNP) and in particular the ile75val SNP in the IL-4 binding region is another risk factor and is associated with increased sensitivity to IL-4 stimulation. It has been reported that the combination of IL-4Rα and IL-13 SNP, ile75val/arg110gln, is associated with more severe asthma. In preliminary studies, we have observed increased frequency of this combination in ABPA asthmatic and CF patients. Another genetic risk factor reported by Brouard et al. is the -1082 GG genotype in the IL-10 promoter in CF patients for the colonization of A. fumigatus and development of ABPA. This genotype was associated with increased plasma IL-10 levels, and perhaps may be associated with increased skewing of Th2 Aspergillus responses rather than down-regulation of inflammatory responses. We hypothesize that increased sensitivity of IL-4 mediated activities secondary to polymorphisms IL-4R in conjunction of other polymorphisms such as IL-13 and IL-10 in conjunction with HLA-DR2/DR5 restriction to Aspergillus antigens in ABPA patients result in increased B-cell activity, monocyte/dendritic cell phenotype that skews Th2 responses, and skewing of Aspergillus-specific Th2 cells. This model system may be applicable to other fungi such as Alternaria and Cladosporium which is associated with increased asthma severity.

Allergic bronchopulmonary aspergillosis in a patient with cystic fibrosis: diagnostic criteria when the IgE level is less than 500 IU/mL

BACKGROUND

Recently, the Cystic Fibrosis Foundation developed a consensus report recommending diagnostic criteria for allergic bronchopulmonary aspergillosis (ABPA) in patients with cystic fibrosis that includes a serum IgE level greater than 500 IU/mL as the "minimal diagnostic criterion."

OBJECTIVE

To describe a 7-year-old girl with ABPA whose serum IgE level increased to only 398 IU/mL.

METHODS

Total IgE and anti-Aspergillus serologic measurements were performed using enzyme-linked immunosorbent assay and standard laboratory techniques; HLA analysis was performed; interleukin 4 receptor alpha single nucleotide polymorphisms were performed using polymerase chain reaction and DNA sequencing; CD23+ B cells were measured using flow cytometry; and cytokine synthesis to Aspergillus purified antigens was assessed using flow cytometry.

RESULTS

A 7-year-old girl with cystic fibrosis who had mild pulmonary disease and well-controlled asthma developed pulmonary infiltrates, increased wheezing, and decreased pulmonary function. Additional studies demonstrated peripheral blood eosinophilia (eosinophil count, 1807 cells/mm3 [19%]) and an increase in IgE and IgG anti-Aspergillus serology; bronchoalveolar lavage revealed septate hyphae with 45 degrees branching subsequently identified as A fumigatus and pulmonary eosinophilia. Previous HLA typing revealed that the patient was HLA-DR2+, DRB*1501, HLA-DQ2-, a pattern associated with increased risk of ABPA. In addition, there was increased up-regulation of CD23 molecules by interleukin 4 stimulation on the patient's B cells, as observed in ABPA. The patient was treated with corticosteroids and itraconazole with resolution of symptoms and pulmonary infiltrates.

CONCLUSIONS

Examination of the pulmonary inflammatory response using bronchoalveolar lavage, genetic risk with HLA-DR2+DQ2- typing, and increased interleukin 4 sensitivity are useful adjunctive studies in the diagnosis of ABPA.

Pathophysiology and immunology of allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is a complication of persistent asthma and cystic fibrosis (CF), diseases in part characterized by excessive viscous mucus and compromised mucociliary clearance. Inhaled conidia of Aspergillus fumigatus are able to persist and germinate, releasing exoproteases and other fungal products that further compromise clearance, breach the epithelium, and activate immune responses. Chemotactic cytokines (e.g. IL-8, RANTES, eotaxin) in particular have been implicated in murine models. Chemokine-mediated recruitment of CD4+TH2 lymphocytes specific for A. fumigatus is a crucial feature of ABPA. Susceptibility also appears to involve immunogenetic factors including atopy and defined major histocompatibility complex-restricted allelic expression on antigen-presenting cells that are permissive for a TH2-predominant immune response. Certain A. fumigatus allergens appear more associated with ABPA rather than simple A. fumigatus allergy. ABPA is characterized by marked local and systemic eosinophilia, an adaptive immune response with elevated levels of A. fumigatus-specific IgG, IgA and IgE antibodies, and a profound nonspecific IL-4-dependent elevation in total IgE. Clinically, ABPA manifests with recurring episodes of asthma, pulmonary infiltrates, and central bronchiectasis that may progress to fibrosis. It is treated with systemic glucocorticoids and azoles. Monitoring clinical, radiographic and serologic responses (especially total IgE) is essential for successful management.

Allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) occurs in nonimmunocompromised patients and belongs to the hypersensitivity disorders induced by Aspergillus. Genetic factors and activation of bronchial epithelial cells in asthma or cystic fibrosis are responsible for the development of a CD(4)+Th2 lymphocyte activation and IgE, IgG and IgA-AF antibodies production. The diagnosis of ABPA is based on the presence of a combination of clinical, biological and radiological criteria. The severity of the disease is related to corticosteroid-dependant asthma or/and diffuse bronchiectasis with fibrosis. The treatment is based on oral corticosteroids for 6-8 weeks at acute phase or exacerbation and itraconazole is now recommended and validated at a dose of 200 mg/day for a duration of 16 weeks.

Pathogenesis of allergic bronchopulmonary aspergillosis and an evidence-based review of azoles in treatment

BACKGROUND

Allergic bronchopulmonary aspergillosis (ABPA) is a complex condition that affects people with asthma and cystic fibrosis (CF). It results from exposure to the fungus Aspergillus fumigatus, which leads to worsening airway inflammation and progressive damage to the lungs. The aim of this review is to outline the pathogenesis of the disorder, diagnostic criteria and to discuss the use of anti-fungal agents in its treatment.

METHODS

The Cochrane library of systematic reviews and the Cochrane database of controlled trials were searched for controlled trials on ABPA and its treatment in both asthma and CF. In addition, articles included within the reviews were examined separately, and a separate search carried out using Medline.

RESULTS

A systematic review for the use of azole anti-fungal agents in ABPA was identified for their use in both CF and non-CF-related disease. The review of ABPA alone identified two randomized-controlled trials of itraconazole in chronic disease. These trials demonstrated improvements in symptoms and immune activation, but were short-term trials and failed to show a significant change in lung function. No trials were identified in CF.

CONCLUSIONS

The use of anti-fungal agents in ABPA seems to be a rational one, with short-term efficacy demonstrated for the use of itraconazole. Further investigations are required to identify individuals who will benefit most from treatment and to establish the correct dose and means of delivering treatment in ABPA. Longer-term studies are required to demonstrate that treatment modifies the progressive decline in lung function seen with the disease.

Immunopathogenesis of allergic bronchopulmonary aspergillosis in cystic fibrosis

Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity lung disease mediated by an allergic late-phase inflammatory response to Aspergillus fumigatus antigens. ABPA is characterized by markedly elevated Aspergillus-specific and total IgE levels and eosinophilia, and manifested by wheezing, pulmonary infiltrates, and bronchiectasis and fibrosis, which afflict asthmatic and cystic fibrosis (CF) patients. We propose that ABPA develops in genetically susceptible CF patients due to HLA-DR2 and DR5 restriction, increased sensitivity to IL-4 stimulation, and increased A. fumigatus allergen-specific Th2 CD4+ T-cell-mediated responses. In addition, A. fumigatus proteases play a role in facilitation of antigen transport across the epithelial cell layer by damaging the epithelial integrity and by a direct interaction with epithelial cell surface receptors, resulting in pro-inflammatory cytokine production and corresponding inflammatory responses.

Allergic bronchopulmonary aspergillosis: a review of a disease with a worldwide distribution

Allergic bronchopulmonary aspergillosis (ABPA), an immunologically mediated lung disease, occurs predominantly in patients with asthma. This chronic relapsing disorder ranges clinically from mild asthma to fatal destructive lung disease and is caused by hypersensitivity to colonized Aspergillus fumigatus (Af). The immunopathogenesis of the disease is yet to be understood clearly. Specific IgE-Af and IgG-Af, the serological markers, contribute to the diagnosis. Radiologically, ABPA is characterized by fleeting pulmonary infiltrates often confused with pulmonary tuberculosis. However, central bronchiectasis on computed tomography is considered to be the hallmark of the disease. Early diagnosis and therapy with prednisolone, the cornerstone of management, could alter the course of the disease and prevent the development of end-stage lung fibrosis.

Sinobronchial allergic mycosis: the SAM syndrome

We contend that the presence of concomitant allergic fungal sinusitis (AFS) and allergic bronchopulmonary mycosis in the same patient represents an expression of the same process of fungal hypersensitivity in the upper and lower airways. We have termed this process the SAM syndrome, an acronym for sinobronchial allergic mycosis. Diagnostic criteria have been established for the SAM syndrome, and the clinical characteristics of one previously unreported and four previously reported patients have been tabulated. Patients with the SAM syndrome have chronic sinusitis involving multiple sinuses, asthma, immediate cutaneous reactivity to fungal allergens, peripheral eosinophilia, and radiographic evidence of bronchiectasis. Total serum IgE levels are usually elevated as well. A variety of chest radiographic abnormalities may occur, ranging from mass lesions to diffuse pulmonary infiltrates and even normal findings on chest radiographs. Patients present for an evaluation of either sinus or lung disease and, at that time, demonstrate no clinical features that distinguish them from patients with isolated sinus or lung disease. All patients reported to date have had clinical responses to therapy with corticosteroids. We postulate that SAM is underdiagnosed in patients with AFS, a disease recently reported from medical centers in the southeastern and western United States. Moreover, since our patient had a mutation in the cystic fibrosis transmembrane conductor regulator (CFTR) gene, we further hypothesize that CFTR gene mutations may play an important role in the pathogenesis of the SAM syndrome.

Peripheral decrease and pulmonary homing of CD4+CD45RO+ helper memory T cells in cystic fibrosis

Interstitial lung disease, although of prognostic impact for patients with cystic fibrosis (CF), remains difficult to assess without histopathologic investigations. As changes of peripheral blood lymphocyte subsets (LS) may accompany severe systemic lymphocyte immune responses, we compared peripheral LS of 44 patients with CF, 23 non-CF patients with recurrent pulmonary infections and 83 healthy controls (flow cytometry; CD3, CD19, CD16, CD56, CD4, CD8, CD11b, CD45RA, CD45RO, HLA-DR and CD25 antigens). Additional immunohistochemistry was performed on lung tissue of four CF patients aged 0.5, 12, 17 and 20 years, respectively. Patients with CF showed low absolute counts of CD4+CD45RO+ memory helperT cells, CD16+CD56+ NK cells, CD8+ and interleukin-2 receptor-positive T cells in peripheral blood (P < 0.001). Similar changes were registered in the non-CF patients with pulmonary infections, indicating that those were not specific for CF. Immunohistochemistry showed activation of bronchus-associated lymphoid tissue with interstitial accumulation of CD4+CD45 RO+ T cells in the three older patients. Patients with CF show marked changes of peripheral blood LS which are presumably not CF-specific and may mirror homing to lung tissue in the course of interstitial lung disease. Further research should evaluate its usefulness in monitoring progression of lung disease in CF.

Diagnosis and treatment of allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is an underdiagnosed pulmonary disorder in asthmatic patients and patients with cystic fibrosis. Its clinical and diagnostic manifestations arise from an allergic response to multiple antigens expressed by fungi, most commonly Aspergillus fumigatus, colonizing the bronchial mucus. The clinical course is one of recurrent exacerbations characterized by chest infiltrates evident on chest x-ray films and associated with cough, wheeze, and sputum production that usually respond to oral corticosteroid treatment. Specific immunologic and radiologic markers of disease include elevation of the total serum IgE levels, presence of aspergillus IgE antibodies, and the occurrence of central bronchiectasis. Long-term treatment with corticosteroids is often required for effective management. The adverse effects of chronic corticosteroid use have led to attempts at treatment with antifungal agents such as itraconazole. Itraconazole has been reported anecdotally to be effective, and evidence for its effectiveness in randomized trials is still accruing. Consideration should be given to its use as a corticosteroid-sparing agent or for treatment of patients in whom corticosteroid response is poor. The natural history and prognosis of ABPA are not well characterized but may be complicated by progression to bronchiectasis and pulmonary fibrosis. If ABPA is diagnosed and treated before the development of bronchiectasis and fibrosis, these complications may be prevented.

Aspergillus fumigatus and aspergillosis

Aspergillus fumigatus is one of the most ubiquitous of the airborne saprophytic fungi. Humans and animals constantly inhale numerous conidia of this fungus. The conidia are normally eliminated in the immunocompetent host by innate immune mechanisms, and aspergilloma and allergic bronchopulmonary aspergillosis, uncommon clinical syndromes, are the only infections observed in such hosts. Thus, A. fumigatus was considered for years to be a weak pathogen. With increases in the number of immunosuppressed patients, however, there has been a dramatic increase in severe and usually fatal invasive aspergillosis, now the most common mold infection worldwide. In this review, the focus is on the biology of A. fumigatus and the diseases it causes. Included are discussions of (i) genomic and molecular characterization of the organism, (ii) clinical and laboratory methods available for the diagnosis of aspergillosis in immunocompetent and immunocompromised hosts, (iii) identification of host and fungal factors that play a role in the establishment of the fungus in vivo, and (iv) problems associated with antifungal therapy.

The spectrum of eosinophilic lung disease: radiologic findings

PURPOSE

Eosinophilic lung disease includes various disease entities. Each disease manifests different radiologic findings. The purpose of this review is to present the radiologic findings of the spectrum of eosinophilic lung disease.

METHOD

We reviewed the radiologic, histologic, and clinical findings of the spectrum of eosinophilic lung disease from the previous reports and our experiences.

RESULTS

Simple pulmonary eosinophilia is characterized by transient and migrating opacities on chest radiography. Acute eosinophilic pneumonia is characterized by acute clinical symptoms and signs and rapid changes of radiographic diffuse reticular lesions. Chronic eosinophilic pneumonia, with more prolonged symptom duration, history of asthma, occurrence of relapse, and radiologic features of subpleural consolidation, can be differentiated from acute eosinophilic pneumonia. Allergic bronchopulmonary aspergillosis presents with bilateral central bronchiectasis with or without mucoid impaction. Although these diseases show specific radiographic findings, some show overlapping radiographic features. High-resolution CT enables characterization of parenchymal lesions further by showing internal and marginal features and the exact extent of the lesions. Extrapulmonary organs are involved in Churg-Strauss syndrome and idiopathic hypereosinophilic syndrome. Asthma is associated with Churg-Strauss syndrome, allergic bronchopulmonary aspergillosis, chronic eosinophilic pneumonia, and bronchocentric granulomatosis.

CONCLUSION

Integration of clinical, laboratory, and radiologic findings enables initial and differential diagnoses of various eosinophilic lung diseases.

A 12-year longitudinal study of Aspergillus sensitivity in patients with cystic fibrosis

STUDY OBJECTIVE

The object of the study was to longitudinally follow immune parameters of Aspergillus fumigatus sensitization so as to predict those at risk for developing allergic bronchopulmonary aspergillosis (ABPA).

DESIGN

Patients were evaluated for 5 immune parameters (skin test [ST], positive precipitating antibody [PPN], total IgE, IgE anti-A fumigatus antibody [IgE-Af], and IgG anti-A fumigatus antibody [IgG-Af]) at yearly intervals over a 12-year time period.

SETTING

Patients were enrolled and evaluated during routine visits to the cystic fibrosis (CF) clinic at Cardinal Glennon Children's Hospital, St. Louis.

PATIENTS

One hundred eighteen patients with documented CF participated.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Six patients were diagnosed as having ABPA. In the non-ABPA patient group, 42% had a positive ST, 42% were PPN positive, 54% had IgE-Af, 61% had IgG-Af, and 10% had an IgE greater than 1,000 IU/mL at some point in time. However, on follow-up, 18% lost skin reactivity, 54% lost-PPN, 53% lost IgE-Af, 45% lost IgG-Af, and IgE greater than 1,000 IU/mL declined more than 72% in 64% of patients. These losses were spontaneous, without systemic corticosteroid intervention.

CONCLUSIONS

Spontaneous diminution and loss of immune parameters in non-ABPA CF patients prevented us from defining a profile of sensitivity likely to result in ABPA. This variability highlights the importance of obtaining follow-up studies and including clinical symptoms when considering the diagnosis of ABPA in patients with CF.

T cell subsets, epitope mapping, and HLA-restriction in patients with allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity lung disease characterized by Aspergillus fumigatus (Af) colonization, IgE and IgG anti-Af antibodies, pulmonary infiltrates, bronchiectasis, and pulmonary fibrosis. Little is known regarding T cell responses and their role in the pathogenesis of ABPA. To examine T cell reactivity to Af antigens, T cell clones (TCC) specific to the Asp f 1 antigen, an 18-kD protein of Af, were established from the peripheral blood of three ABPA patients. The majority of TCC isolated from ABPA patients, and specific for the Asp f 1 allergen of Af, are IL-4 producing CD4+ cells of the Th2 phenotype. Further analysis in this study revealed that the majority of TCC reacted to mainly two epitopes of Asp f 1, while the remaining TCC reacted to three additional "minor" epitopes. Blocking studies using monoclonal antibodies specific for class II HLA-D region gene products showed that most TCC, 19/21, were restricted by HLA-DR molecules, and the remaining two clones by HLA-DP molecules. The use of a panel of HLA-matched and mismatched EBV-transformed B cells as antigen presenting cells revealed that the HLA-DR restriction was mediated exclusively by either the HLA-DR2 or HLA-DR5 alleles. Genotyping of DRB1 gene products showed that class II presentation for most clones was not restricted to a single allele, representing DRB1 gene products of either HLA-DR2 or DR5. These studies offer insight into the cellular and molecular determinants which contribute to the immunopathophysiology of ABPA.

Immunohistochemical detection of GM-CSF, IL-4 and IL-5 in a murine model of allergic bronchopulmonary aspergillosis

BACKGROUND

Granulocyte macrophage-colony stimulating factor (GM-CSF), interleukin-4 (IL-4) and IL-5 are important in tissue eosinophil accumulation and high IgE production in allergic inflammatory reaction.

OBJECTIVE

We examine lung GM-CSF, IL-4 and IL-5 expression in a murine model of allergic bronchopulmonary aspergillosis (ABPA) characterized by eosinophil and lymphocyte lung infiltration and elevated serum IgE level.

METHODS

C57BL/6 mice were intranasally treated three times a week for 1, 2 or 3 week(s) with Aspergillus fumigatus (Af) antigen or saline and were sacrificed on days 7, 14 and 21. Immunohistochemical analyses for GM-CSF, IL-4 and IL-5 were performed on lung sections.

RESULTS

Af treatment induced a remarkable pulmonary eosinophil influx. Increased numbers of lung T lymphocytes and GM-CSF positive cells were observed on days 14 and 21. IL-4 and IL-5 positive cells were increased significantly only on day 14. Immunostained serial sections showed that most (> or = 98%) cytokine positive cells were CD3 positive. Few eosinophils (< 2% of cytokine positive cells) were immunoreactive for GM-CSF and IL-5. Significant correlations were found between the number of GM-CSF and IL-5 positive cells, and the number of eosinophils in Af-treated lung (r = 0.62, P < 0.05 and r = 0.52, P < 0.05 respectively), and between the number of IL-4 positive cells and the serum total IgE level (r = 0.64, P < 0.01).

CONCLUSIONS

Our data suggest a role for T lymphocyte GM-CSF, IL-4 and IL-5 in Af-induced mouse pulmonary eosinophilia and increased serum IgE production and further support the importance of T helper (TH2) cells in the pathogenesis of ABPA.

The pathology of fungal disease in the lung

The gross and histological appearance of pulmonary mycotic disease is rarely pathognomonic for a particular entity. Tissue obtained through an invasive procedure is usually necessary for a specific diagnosis. Pathological diagnosis is directed by the pattern of inflammation and based on the morphological identification of fungi. The interventional radiologist plays a critical role in the diagnosis of pulmonary mycoses by obtaining additional material for culture. An open and inquisitive collaboration between the radiologist and pathologist can improve diagnostic accuracy for both specialists.

Clinical significance of the recovery of Aspergillus species from the respiratory secretions of cystic fibrosis patients

The frequent recovery of Aspergillus species from the respiratory tract secretions of cystic fibrosis (CF) patients is well recognized, and the presence of the fungus in the airways may trigger an inflammatory response that can manifest as the clinical entity known as allergic bronchopulmonary aspergillosis (ABPA). In our CF patient population we studied the clinical characteristics of those who had Aspergillus sp. recovered from their respiratory tract secretions (n = 45) and compared them with the characteristics seen, during the same time period, in those patients who were culture negative for Aspergillus sp. (n = 167). There were no differences in peripheral blood eosinophil count (P = 0.9) or serum immunoglobulin E levels (P = 0.61). By logistic regression analysis there seemed to be an increased risk for more advanced lung disease, both radiographically (defined by a Brasfield chest radiograph score < 18) and by lung function parameters in those who were culture positive. However, after appropriate adjustment, almost all the increased risk was associated with age and gender, but not with the presence of Aspergillus sp. in respiratory secretions. Additionally, increasing age was strongly correlated with the risk of Aspergillus sp. being cultured from respiratory secretions (P = 0.0025). The presence of Aspergillus sp. in respiratory secretions was not associated with two indicators of atopy in our CF patient population. We do not have evidence that the culture of Aspergillus sp. from CF respiratory secretions is independently associated with an increased risk for more advanced lung disease.

Experimental allergic bronchopulmonary aspergillosis in the mouse: immunological and histological features

C57BL/6 mice treated with intranasal instillation of 100 micrograms of Aspergillus antigen three times a week developed a pulmonary eosinophilia, observed in the bronchoalveolar lavage (BAL) and on histopathological examination. At week 3, the instillation of Aspergillus antigen provoked a 10-fold increase in the BAL cell number and eosinophils were the predominant inflammatory cells (66.4%). Histopathological findings showed focal alveolar lesions with peribronchial and perivascular infiltration of lymphoid cells, numerous eosinophils, epithelioid cells, and granulomas with giant cells. Increases in total IgE and IgG1 levels in BAL fluid (33-fold and 14-fold) and serum (67-fold and 8-fold) were observed also (P < 0.05). IgG1 specific to Aspergillus fumigatus (Af) was detected only in the antigen-treated mice. At 12 weeks, there was a persistent but less intense eosinophilia both in BAL and on histopathological examination accompanied by steadily elevated total IgE and total IgG1 and a higher level of specific IgG1-Af in BAL fluids and sera. No bronchocentric granulomatosis, mucoid impaction nor bronchiectasis could be observed. Data from the study described here showed that in mice repeated exposure to Aspergillus antigen leads to a strong inflammatory pulmonary response, characterized by remarkable pulmonary eosinophilia and elevations of total IgE, total IgG1 and specific IgG1-Af in both BAL and serum, which are the hallmarks of human allergic bronchopulmonary aspergillosis also. However, this inflammation did not induce the chronic histological features of the human disease.

Environmental exposure to Aspergillus fumigatus allergen (Asp f I)

Asp f I is a major allergen produced by the mycelia of Aspergillus fumigatus. It is not present in spores and can be used as a specific marker for the detection of germination of this fungus. We investigated the domestic and outdoor concentration of Asp f I in Poole, U.K. and Charlottesville, VA, U.S.A. Asp f I was undetectable in 95% (281/296) of house dust extracts and present at low levels (< 0.17 micrograms/g of sieved dust, mean 0.038 micrograms/g) in the remainder. In contrast, Asp fI could be detected in 65% (15/23) of cultures of house dust, suggesting the presence of viable, but ungerminated, A. fumigatus in the majority of homes. Asp f I was detectable in 80% (28/35) of extracts of leaves and compost, but present in these outdoor samples at low levels (< 0.11 micrograms/g, mean 0.27 micrograms/g). Air sampling for Asp f I was undertaken before and after vigorous disturbances at indoor (n = 5) and outdoor (n = 6) sites. Airborne Asp f I was not detected in domestic samples or in undisturbed outdoor samples. Following disturbance it could be measured in outdoor samples (range 7.6-29 ng/m3). The results suggest that while exposure to A. fumigatus is common, exposure to Asp f I and germinating A. fumigatus is uncommon. It is probable that those individuals who develop antibody responses to Asp f I have been exposed to A. fumigatus which has germinated in their respiratory tract.