Asp f I CD4 + TH2-like T-cell lines in allergic bronchopulmonary aspergillosis

Risk factors for nontuberculous mycobacterial isolation in patients with cystic fibrosis: A meta-analysis

BACKGROUND

To better understand the mechanisms of infection with nontuberculous mycobacteria (NTM) in patients with cystic fibrosis (CF), we explore different risk factors associated with NTM positivity in a meta-analysis.

METHODS

Studies published before 31 July 2019 were selected from MEDLINE. Combined odds ratios (ORs) were calculated by pooling the ORs of each study. The weighted mean difference (WMD) was used for continuous numerical measurements. Summary data were pooled using fixed- or random-effects models according to the presence of heterogeneity (P < .1 or I²  > 50%).

RESULTS

Nineteen studies with a total of 23 418 patients, of whom 1421 (6%) were diagnosed as NTM positive, were included. Older age was significantly associated with NTM positivity (WMD = 2.12, 95% confidence interval [CI]: 1.11-3.13; P < .01, fixed-effects model). The OR for Staphylococcus aureus colonization was 1.66 (95% CI: 1.21-2.26; P = .001) in 11 studies (8091 patients), the OR for Aspergillus fumigatus colonization was 3.59 (95% CI: 3.05-4.23; P < .001) in 11 studies (20 480 patients), and the OR for Stenotrophomonas maltophilia colonization was 3.41 (95% CI: 2.66-4.39; P < .01) in seven studies (14 935 patients). Oral corticosteroids were significantly associated with NTM positivity (OR = 1.98, 95% CI: 1.24-3.16; P < .01, 6 studies, 1936 patients). No other factor showed a significant association.

CONCLUSION

Older age, S. aureus, S. maltophilia, and A. fumigatus chronic colonization, and oral corticosteroids were significantly associated with an increased risk of NTM positivity. CF patients with more severe conditions should be closely monitored for NTM.

Fungus-Specific CD4 T Cells as Specific Sensors for Identification of Pulmonary Fungal Infections

Patients with cystic fibrosis (CF) suffer from chronic lung infections, caused by bacterial, viral or fungal pathogens, which determine morbidity and mortality. The contribution of individual pathogens to chronic disease and acute lung exacerbations is often difficult to determine due to the complex composition of the lung microbiome in CF. In particular, the relevance of fungal pathogens in CF airways remains poorly understood due to limitations of current diagnostics to identify the presence of fungal pathogens and to resolve the individual host-pathogen interaction status. T-lymphocytes play an essential role in host defense against pathogens, but also in inappropriate immune reactions such as allergies. They have the capacity to specifically recognize and discriminate the different pathogens and orchestrate a diverse array of effector functions. Thus, the analysis of the fungus-specific T cell status of an individual can in principle provide detailed information about the identity of the fungal pathogen(s) encountered and the actual fungus-host interaction status. This may allow to classify patients, according to appropriate (protective) or inappropriate (pathology-associated) immune reactions against individual fungal pathogens. However, T cell-based diagnostics are currently not part of the clinical routine. The identification and characterization of fungus-specific T cells in health and disease for diagnostic purposes are associated with significant challenges. Recent technological developments in the field of fungus-specific T helper cell detection provide new insights in the host T cell-fungus interaction. In this review, we will discuss basic principles and the potential of T cell-based diagnostics, as well as the perspectives and further needs for use of T cells for improved clinical diagnostics of fungal diseases.

Immunoproteomics of Aspergillus for the development of biomarkers and immunotherapies

Filamentous fungi of the genus Aspergillus play significant roles as pathogens causing superficial and invasive infections as well as allergic reactions in humans. Particularly invasive mycoses caused by Aspergillus species are characterized by high mortality rates due to difficult diagnosis and insufficient antifungal therapy. The application of immunoproteomic approaches has a great potential to identify new targets for the diagnosis, therapy, and vaccine development of diseases caused by Aspergillus species. Serological proteome analyses (SERPA) that combine 2D electrophoresis with Western blotting are still one of the most popular techniques for the identification of antigenic proteins. However, recently a growing number of approaches have been developed to identify proteins, which either provoke an antibody response or which represent targets of T-cell immunity in patients with allergy or fungal infections. Here, we review advances in the studies of immune responses against pathogenic Aspergilli as well as the current status of diagnosis and immunotherapy of Aspergillus infections.

Epidemiology of nontuberculous mycobacteria (NTM) amongst individuals with cystic fibrosis (CF)

BACKGROUND

Infection by nontuberculous mycobacteria (NTM) in patients with cystic fibrosis (CF) is often associated with significant morbidity. Limited, conflicting results are published regarding risk factors for pulmonary NTM disease. We analysed factors potentially associated with NTM in a large population of European patients with CF.

METHODS

We investigated associations between presence of NTM and various factors for patients registered in the European Cystic Fibrosis Society Patient Registry.

RESULTS

374 (2.75%) of 13,593 patients studied had at least one positive NTM culture within the study year. Age- and FEV1-adjusted odds of NTM infection was more than 2.5 times higher (95%CI: 1.79; 3.60) in patients infected by Stenotrophomonas maltophilia than in patients not infected (p<0.0001), 2.36 times higher (95%CI: 1.80;3.08) in patients with ABPA than without (p<0.0001), 1.79 times higher (95%CI: 1.34; 2.38) in patients who use bronchodilators than in patients who don't (p<0.0001), 1.49 times higher (95%CI: 1.18; 1.89) in patients who use inhaled antibiotics than in patients who don't (p=0.001), and 1.30 times higher (95%CI: 1.02; 1.66) in patients who use rhDNase than in patients who don't (p=0.032).

CONCLUSIONS

NTM-positive cultures in individuals with CF are associated with distinct clinical variables. Improved data collection identifying risk factors for NTM infection will allow more focused screening strategies, and influence therapeutic choices and infection control measures in high-risk patients.

T helper 2 response in allergic bronchopulmonary aspergillosis is not driven by specific Aspergillus antigens

Allergic bronchopulmonary aspergillosis (ABPA) is characterized by an allergic immunological response to Aspergillus fumigatus. In this study, we investigated whether certain Aspergillus antigens are more allergenic than others, as was postulated previously. We stimulated peripheral blood mononuclear cells from patients with ABPA with the classically described A. fumigatus allergens Aspf1, Aspf2, Aspf3, and Aspf4, as well as two other Aspergillus antigens, Crf1 and Catalase1. Activated CD4+ T cells displayed a T helper 2 phenotype with the production of IL-4 in response to stimulation with several of these different antigens. Immune responses were not limited to the classically described A. fumigatus allergens. In healthy individuals, we demonstrated a similar recognition profile to the different antigens, but in contrast the activated CD4+ T cells exerted a T helper 1 phenotype and mainly produced IFN-γ after stimulation with A. fumigatus antigens. In conclusion, irrespective of the A. fumigatus antigen, the T-cell immune response in patients with ABPA is skewed to a T helper 2 cytokine secretion profile.

Molecular biology and immunology of fungal allergens

Fungi are non-chlorophyllus microorganisms, which constitutes the main source of outdoor and indoor allergens. The antigens present in the spores and fragments of hyphae induce allergic responses in sensitized patients. The frequently recognized fungi associated with asthma include Alternaria, Cladosporium, Aspergillus, and Penicillium. With the advent of molecular biology techniques a number of fungal genes encoding relevant allergens have been cloned and the expressed allergens purified and characterized. In this review, we have presented the recent developments, where recombinant allergens have been used in the precise diagnosis of fungal allergy. We have also discussed the role played by these allergens and the T- and B-cell epitopes in the immune mechanism in fungal allergy.

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.

Triggering receptor expressed on myeloid cells-1 (TREM-1) modulates immune responses to Aspergillus fumigatus during fungal asthma in mice

Triggering receptor expressed on myeloid cells-1 (TREM-1) expression is increased during pulmonary fungal infection suggesting that this receptor might be involved in anti-fungal immune responses. To address the role of TREM-1 in a murine model of fungal allergic airway disease, A. fumigatus-sensitized CBA/J mice received by intratracheal injection a mixture of live A. fumigatus conidia and one of a control adenovirus vector (Ad70), an adenovirus containing a gene encoding for the extracellular domain of mouse TREM-1 and the F(c) portion of human IgG (AdTREM-1Ig; a soluble inhibitor of TREM-1 function), or an adenovirus containing mouse DAP12 (AdDAP12; DAP12 is an intracellular adaptor protein required for TREM-1 signaling), and examined at various days after challenge. Whole lung TREM-1 levels peaked at day 3 whereas circulating TREM-1 levels peaked at day 30 in this fungal asthma model. AdTREM-1Ig-treated mice exhibited significantly higher airway hyperresponsiveness following methacholine challenge compared with Ad70- and AdDAP12-treated mice. Whole lung analysis of AdTREM-1Ig treated mice revealed markedly higher amounts of fungal material compared with the other groups. ELISA analysis of whole lung and bronchoalveolar lavage samples indicated that several pro-allergic cytokine and chemokines including CCL17 and CCL22 were significantly increased in the AdTREM-1Ig group compared with the other groups. Finally, Pam3Cys and soluble Aspergillus antigens induced TREM-1 transcript expression in macrophages in a TLR2 dependent manner. In conclusion, TREM-1 modulates the immune response directed against A. fumigatus during experimental fungal asthma.

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.

A comparison between intratracheal and inhalation delivery of Aspergillus fumigatus conidia in the development of fungal allergic asthma in C57BL/6 mice

Allergic asthma is a debilitating disease of the airways characterized by airway hyperresponsiveness, eosinophilic inflammation, goblet cell metaplasia with associated mucus hypersecretion, and airway wall remodelling events, particularly subepithelial fibrosis and smooth muscle cell hyperplasia. Animal models that accurately mimic these hallmarks of allergic airways disease are critical for studying mechanisms associated with the cellular and structural changes that lead to disease pathogenesis. Aspergillus fumigatus, is a common aeroallergen of human asthmatics. The intratracheal (IT) delivery of A. fumigatus conidia into the airways of sensitized mice has been described as a model of allergic disease. Here, we compared the IT model with a newly developed inhalation (IH) challenge model. The IH model allowed multiple fungal exposures, which resulted in an exacerbation to the allergic asthma phenotype. Increased recruitment of eosinophils and lymphocytes, the hallmark leukocytes of asthma, was noted with the IH model as compared to the IT model in which macrophages and neutrophils were more prominent. Immunoglobulin E (IgE) production was significantly greater after IH challenge, while that of IgG(2a) was higher after IT challenge. Airway wall remodelling was pronounced in IH-treated mice, particularly after multiple allergen challenges. Although the IT model may be appropriate for the examination of the played by innate cells in the acute response to fungus, it fails to consistently reproduce the chronic remodelling hallmarks of allergic asthma. The ability of the IH challenge to mimic these characteristics recommends it as a model suited to study these important events.

The utility of antifungal agents for asthma

PURPOSE OF REVIEW

Recent work demonstrates that patients with refractory asthma are likely to be sensitized to environmental fungi and that specific antifungal treatments may be of benefit to this group.

RECENT FINDINGS

The relationships among fungal sensitization, exposure and asthma severity are imperfectly understood. Exposure to environmental fungi occurs ubiquitously and there is emerging evidence that internal airways colonization could be a source of ongoing exposure. Antifungal treatments appear to improve asthma-related quality of life. Such treatments are generally well tolerated but there are potential side-effects. The mechanisms behind the clinical improvements are not yet fully established.

SUMMARY

Antifungal treatments are used in some centres for patients with refractory asthma. Further research needs to explore the questions of patient selection, optimum duration of therapy and the prediction and management of azole-corticosteroid drug interactions. Advances in our understanding of the fungal molecular allergome and in our understanding of the allergic importance of small hyphal fragments may help to more precisely define the relationships among fungal sensitization, exposure and asthma severity.

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.

HLA-DRB1 alleles control allergic bronchopulmonary aspergillosis-like pulmonary responses in humanized transgenic mice

BACKGROUND

Allergic bronchopulmonary aspergillosis (ABPA) is a lung hypersensitivity disease mediated in part by CD4(+) T(H)2 cells. There is a significant association between ABPA and the HLA-DR2 genotypes DRB1(*)1501 and DRB1(*)1503, whereas resistance might be associated with HLA-DRB1(*)1502.

OBJECTIVE

We sought to elucidate the role of HLA-DR alleles in allergic inflammation in lungs.

METHODS

HLA-DR humanized transgenic mice expressing either the susceptible or resistant alleles were analyzed for the nature and extent of pulmonary inflammation after exposure to Aspergillus species antigens.

RESULTS

Exposed DRB1(*)1501 and DRB1(*)1503 transgenic mice displayed infiltrates made up prominently of eosinophils, which is consistent with the inflammation found in ABPA. The resistant DRB1(*)1502 mice, on the other hand, displayed minimal to moderate inflammation, consisting mainly of T-cell infiltrates. Significantly more mucin was produced in the DRB1(*)1503 and DRB1(*)1501 mice, and their ability to limit the number of Aspergillus species conidia within the lung parenchyma was impaired. Despite their differences, both the DRB1(*)1503 and DRB1(*)1502 strains mounted comparable T cell-proliferative responses to Aspergillus species antigens.

CONCLUSION

The HLA-DR2 alleles DRB1(*)1501 and DRB1(*)1503 play a major role in the development of allergic pulmonary inflammation. In contrast, the HLA-DR2 allele DRB1(*)1502 mediates a nonallergic T(H)1-like response to the organism, possibly explaining an ABPA resistance factor. These results are in support of our published human studies in patients with cystic fibrosis and asthma.

CLINICAL IMPLICATIONS

HLA-DR typing in patients with cystic fibrosis and asthma will aid in the identification of individuals at risk for ABPA.

Infectious disease, the innate immune response, and fibrosis

The unrelenting and destructive progression of most fibrotic responses in the pulmonary, cardiovascular, integumentary, and alimentary systems remains a major medical challenge for which therapies are desperately needed. The pathophysiology of fibrosis remains an enigma, but considerable research and debate surrounds the question of whether chronic inflammation is the key driver of unrestrained wound healing (i.e., the fibrotic response) in these and other organ systems. This Review describes how infectious pathogens, chronic inflammation, and unrestrained fibroproliferation are likely to be part of a dynamic, unrelenting process propelling human fibrotic diseases.

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.

Generation of cytotoxic T cell responses directed to human leucocyte antigen Class I restricted epitopes from the Aspergillus f16 allergen

Invasive aspergillosis (IA) is a major cause of infection-related mortality in patients with haematological malignancies, especially in recipients of haematopoietic stem cell transplants. We have prepared overlapping pentadecapeptides (11-aa overlap with previous peptide) spanning the entire 427-aa coding region of the Aspergillus allergen, Asp f16 shown previously in mice to induce Th1-type cell responses in vivo and in humans to induce proliferative and cytotoxic CD4(+) T cell responses. Mature dendritic cells (DC) pulsed with a complete pool of peptides were used to generate T cell lines. Two lines from HLA-B*3501(+) donors were found to be strongly cytotoxic to autologous Asp f16-peptide pool- and Aspergillus culture extract-pulsed targets after 4-5 weekly primings. Cytotoxic T lymphocyte (CTL) culture supernatant killed Aspergillus conidia, and cells directly killed Aspergillus hyphae. Cytotoxic activity and interferon (IFN)-gamma production were mediated exclusively by CD8(+) T cells in response to pool-pulsed targets. Interleukin (IL)-4 production was not detected. CTL activity was restricted by HLA-B*3501 and based on peptide prediction programmes was most probably directed to YFKYTAAAL (YFK), LPLCSAQTW (LPL) and GTRFPQTPM (GTR) in one donor, while only LPL was recognized by CTL from the second donor. Pool-pulsed B*3503(+) BLCL but not B*3502(+) or B*3508(+) BLCL presented peptide to donor no. 1. B*3503(+) BLCL presented YFK and to a lesser extent GTR, but not peptide LPL. Our data show that in addition to our previously identified Class II restricted peptide response, DC pulsed with a pentadecapeptide pool from Asp f16 are capable of inducing polyclonal, HLA-Class I-restricted, Aspergillus-specific T cells that may be capable of conferring immunity to IA.

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.

Mannose-binding lectin deficiency alters the development of fungal asthma: effects on airway response, inflammation, and cytokine profile

Aspergillus fumigatus is a major fungal pathogen that may be fatal to immunocompromised individuals and causes airway hyperreactivity and remodeling in sensitized individuals. Herein, we examined the role of mannose-binding lectin (MBL), a complement-activating plasma protein, during pulmonary innate and allergic immune responses directed against A. fumigatus spores or conidia. Neither group of nonsensitized MBL-A-sufficient (MBL-A+/+) nor -deficient (MBL-A-/-) mice challenged with an intravenous or intratracheal (i.t.) bolus of A. fumigatus spores experienced fungus-induced mortality, but marked airway remodeling was observed in MBL-A-/- mice challenged i.t. with conidia. In a model of chronic fungal asthma, MBL-A+/+ and MBL-A-/- A. fumigatus-sensitized mice were examined at days 4 and 28 after an i.t. challenge with A. fumigatus conidia. Airway hyperresponsiveness in sensitized MBL-A-/- mice was significantly decreased at both times after conidia challenge compared with the sensitized MBL-A+/+ group. In the sensitized MBL-A-/- mice, whole lung T helper cell type 2 cytokine levels were significantly decreased at day 4 after conidia, and whole lung interferon-gamma levels were significantly increased at day 28 after conidia when compared with controls. However, histological evidence showed similar airway remodeling at day 28 after conidia (i.e., subepithelial fibrosis and goblet cell metaplasia) in the two groups of mice. Thus, these findings show that MBL-A is not required for mouse survival following exposure to A. fumigatus conidia, and this murine collectin isoform contributes to the development and maintenance of airway hyperresponsiveness but not chronic airway remodeling during chronic fungal asthma.

IgE antibody to Aspergillus fumigatus recombinant allergens in cystic fibrosis patients with allergic bronchopulmonary aspergillosis

BACKGROUND

Allergic bronchopulmonary aspergillosis (ABPA) in cystic fibrosis (CF) is characterized by a heightened Th2 CD4+ T-cell response to Aspergillus fumigatus (Af) allergens and a hyper-immunoglobulin E (IgE) state compared with cystic fibrosis patients without ABPA. The IgE serologic differentiation of ABPA from atopic CF patients can be difficult. We propose as the reactivity with purified antigens varies qualitatively and quantitatively and that the antibody response is more specific than with crude Af antigen extract, the IgE responses to purified recombinant Af allergens may differentiate ABPA from atopic CF patients.

METHODS

Serum IgE reactivity to seven recombinant purified allergens and to a crude extract of Af was measured in 15 ABPA, in 23 Af skin test positive (ST+), and in 19 Af skin test negative (ST-) CF patients. Four of the ABPA CF patients were studied before and after developing ABPA. Nine ABPA patients were studied during flares and remissions of ABPA.

RESULTS

Allergic bronchopulmonary aspergillosis patients had significantly increased IgE reactivity to Asp f2, f3, f4, f6, and f16 compared with the Af ST+ and ST- non-ABPA CF patients. In the ABPA patients studied before and after developing ABPA, IgE reactivity also increased to Asp f2, f3, f4, and f6, and to the crude extract. In ABPA CF patients, IgE reactivity to Asp f1, f2, f3, and f6 significantly increased during periods of ABPA flares compared with periods of remission. Analysis of the receiver operating curve demonstrated that IgE reactivity to Asp f3 and f4 gave the best sensitivity and specificity and were better than IgE reactivity to a crude extract of Aspergillus. Furthermore, in ABPA patients studied during periods of remission the IgE reactivity to Asp f3 and f4 remained significantly elevated compared with Af ST+ non-ABPA patients. The IgE responses when considered either to be positive or negative to Asp f3 and f4 significantly differentiated ABPA from Af ST+ and ST- non-ABPA CF patients. In contrast, IgE reactivity was considered positive to the crude extract in 89% of ABPA, 61% of Af ST+, and 0% of Af ST- non-ABPA CF patients.

CONCLUSIONS

Immunoglobulin E reactivity to a panel of purified Af allergens, especially to Asp f3 and f4, differentiates ABPA from atopic Af ST+ non-ABPA CF patients. Serial determinations of IgE reactivity to individual purified Aspergillus antigens, especially Asp f3, demonstrates that increases in IgE reactivity may provide improved distinction between stages of flares and remission compared with changes in IgE reactivity to a crude Aspergillus extract.

Increased sensitivity to IL-4 in cystic fibrosis patients with allergic bronchopulmonary aspergillosis

BACKGROUND

Allergic bronchopulmonary aspergillosis (ABPA) is characterized by a heightened Th2 CD4+ T-cell response to Aspergillus fumigatus allergens and a hyper-immunoglobulin (Ig)E state compared with cystic fibrosis patients without ABPA. We hypothesize that one reason for this response is increased sensitivity to interleukin (IL)-4 in ABPA resulting in increased expression of CD23 and CD86 and leading to a positive amplification mechanism that increases Th2 CD4+ T cell responses.

METHODS

Peripheral blood mononuclear cells (PBMC) were isolated from seven ABPA CF and 19 non-ABPA CF patients and 16 nonatopic controls and stimulated with rIL-4 (range 0.1-10 ng/ml) and rIL-13 (range 1-10 ng/ml) for 48 h. The number of CD23 molecules and percentages of CD23+ B cells were quantified by flow cytometry. Both phorbol 12-myristate 13-acetate (PMA)/ionomycin (IO) and antigen stimulated, toxoid and Asp f2/f3/f4, PBMC were examined for cytoplasmic cytokine synthesis enumerated by cytokine staining using flow cytometry to measure Th2 and Th1 CD3+ T cells.

RESULTS

The numbers of CD23 molecules on B-cells were significantly elevated at time 0 in ABPA CF patients compared with both non-ABPA CF patients and nonatopic controls. Following IL-4 stimulation in vitro, the numbers and percentages of CD23 expression on B cells were significantly up-regulated in ABPA CF patients compared with non-ABPA CF patients and controls. The IL-13 stimulation up-regulated CD23 expression; however, there was no significant difference in ABPA CF patients compared with non-ABPA CF patients and controls. The percentages of interferon (IFN)-gamma+ CD3+T cells following PMA/IO stimulation were significantly decreased in both ABPA and non-ABPA CF patients compared with controls. There were no significant differences of IL-4+ and IL-13+ CD3+ T cells between ABPA and non-ABPA CF patients. When tetanus toxoid stimulated T cells were examined, both ABPA and non-ABPA CF patients had significantly decreased IFN-gamma+ CD3+ T cells compared with controls. In Asp f2/f3/f4 stimulated T cells, ABPA CF patients had significantly increased IL-4+ CD3+ T cells compared with non-ABPA CF patients and controls.

CONCLUSIONS

ABPA CF patients have increased sensitivity to IL-4 but not to IL-13 up-regulation of CD23 molecules compared with non-ABPA CF patients. There were decreased percentages of IFN-gamma+ and IL-2+ Th1 T cells in CF patients compared with nonatopic controls but similar percentages of IL-4+ Th2 T cells in all three groups. However, ABPA CF patients had increased frequency of Aspergillus-stimulated Th2 T cells. This indicated that there is skewing of Th2 T cells in ABPA CF patients. Thus, in CF ABPA patients there is increased Th2 T cells and increased sensitivity to IL-4.

Fungal allergens

Many fungi are capable of causing IgE-mediated hypersensitivity in humans. However, the most predominant fungi implicated in allergy belong to the genera Aspergillus, Alternaria, Cladosporium, and Penicillium. Pure and relevant allergens are essential for diagnosis as well as for understanding the immunopathogenesis of the disease. Until recently, pure and standardizable antigens from fungi were not available. In recent years, many recombinant allergens have been produced by molecular cloning. Using these allergens, novel methods are being developed to improve diagnosis of mold-induced allergy. By understanding the immunopathogenesis of allergens, new avenues might open up leading to improved patient care, including immunotherapy and vaccination. This review covers the current status of fungal allergens, their role in reliable immunodiagnosis, and their probable use in immunotherapy and vaccination.

Association of polymorphisms in the collagen region of SP-A2 with increased levels of total IgE antibodies and eosinophilia in patients with allergic bronchopulmonary aspergillosis

BACKGROUND

Studies from our group have shown a protective role of pulmonary surfactant protein A (SP-A) against lung allergy and infections caused by Aspergillus fumigatus.

OBJECTIVE

Present study investigated the association of polymorphisms in the collagen region of SP-A1 and SP-A2 (genes encoding SP-A) with allergic bronchopulmonary aspergillosis (ABPA) and its clinical markers.

METHODS

Genomic DNA was extracted from blood samples of patients with ABPA and age-matched, unrelated control subjects. The polymorphisms were detected by means of PCR amplification and sequencing of the collagen region of SP-A1 and SP-A2.

RESULTS

Two exonic (SP-A2 G1649C and SP-A2 A1660G, 10 patients and 11 control subjects) and 2 intronic (SP-A2 T1492C, 8 patients and 8 control subjects; SP-A1 C1416T, 5 patients and 7 control subjects) polymorphisms in the collagen region of SP-A2 and SP-A1 showed significant association with patients with ABPA. A significantly higher frequency of the AGA allele (A1660G) of SP-A2 was observed in patients with ABPA in comparison with control subjects (P =.0156, odds ratio [OR] = 4.78, 95% CI = 1.23 < OR < 18.52). This polymorphism, when existing along with a nonredundant polymorphism, SP-A2 G1649C (Ala91Pro) resulted in a stronger association with ABPA (A1660G and G1649C: P =.0079, OR = 10.4, 95% CI = 1.62 < OR < 66.90). Patients with ABPA with GCT and AGG alleles showed significantly high levels of total IgE and percentage eosinophilia versus patients with ABPA with CCT and AGA alleles.

CONCLUSION

The results indicated that SP-A2 G1649C and SP-A2 A1660G, polymorphisms in the collagen region of SP-A2, might be one of the contributing factors to genetic predisposition and severity of clinical markers of ABPA.

IL-10 controls Aspergillus fumigatus- and Pseudomonas aeruginosa-specific T-cell response in cystic fibrosis

Up to 90% of patients with cystic fibrosis (CF) are chronically colonized with Pseudomonas aeruginosa, and 10% to 50% of CF patients are colonized with Aspergillus fumigatus. Despite an extensive inflammatory reaction, patients cannot eliminate the microorganisms. The present study demonstrates that an IL-10 mediated T-cell tolerance to major infectious agents A. fumigatus and P. aeruginosa plays an important role in the control of T-cell-mediated inflammatory responses in CF. Peripheral blood mononuclear cells of CF patients secreted significantly higher amounts of IL-10. T-cell response against recombinant A. fumigatus antigens rAsp f 3, rAsp f 4, rAsp f 6, and heat-inactivated P. aeruginosa was controlled by IL-10. Proliferation and interferon-gamma production was significantly increased when endogenous IL-10 was blocked in aspergillus and pseudomonas antigen-stimulated cells of CF patients. The role of IL-10 was further documented by increased spontaneous proliferation of peripheral blood mononuclear cells of CF patients after preincubation with antisense oligonucleotides blocking the synthesis of IL-10 receptor-associated kinases janus tyrosine kinase 1 and tyrosine kinase 2. Together, these data demonstrate an important role of IL-10-mediated peripheral T-cell tolerance to P. aeruginosa and A. fumigatus in the control of the intensity of the inflammatory T-cell response in CF.

Aspergillosis. Pathogenesis, clinical manifestations, and therapy

Diseases caused by Aspergillus species are increasing in importance, especially among immunocompromised hosts. Clinical manifestations are variable, ranging from allergic to invasive disease, largely depending on the status of the host's immune system. This article focuses on the pathogenesis and clinical manifestations of diseases caused by Aspergillus species, with more detailed discussion on therapy of the most morbid manifestation, invasive aspergillosis.

Vaccination of mice against invasive aspergillosis with recombinant Aspergillus proteins and CpG oligodeoxynucleotides as adjuvants

In a murine model of invasive pulmonary aspergillosis, dendritic cells (DCs) pulsed with Aspergillus antigens induced the activation of CD4(+) Th1 cells capable of conferring resistance to the infection. Here we show that the combined, local delivery of unmethylated CpG oligodeoxynucleotides (ODNs) and the Asp f 16 Aspergillus allergen resulted in the functional maturation and activation of airway DCs capable of inducing Th1 priming and resistance to the fungus. Therefore, ODNs act as a potent adjuvant for the vaccine-induced protection against the fungus by promoting dominant Th1 response to Aspergillus antigens and allergens.

Allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) complicates asthma and cystic fibrosis. The survival factors in Aspergillus fumigatus that support saprophytic growth in bronchial mucus are not understood. Prednisone remains the most definitive treatment but need not be administered indefinitely. MHC II -restricted CD4(+) T( H)2 clones have been derived from patients with ABPA. The total serum IgE concentration is elevated sharply but is "nonspecific. " IgE serum isotypic antibodies to A fumigatus are useful in diagnosis; this is in contrast to the situation for patients with asthma without ABPA. High-resolution computed tomography of the chest demonstrates multiple areas of bronchiectasis in most patients with ABPA and is a useful radiologic tool. Some asthma control patients might have a few bronchiectatic airways, but not to the extent seen in or of the same character as those in ABPA. This review discusses clinical, radiologic, investigational, pathogenetic, and treatment issues of ABPA.

T cell proliferation and cytokine secretion to T cell epitopes of Asp f 2 in ABPA patients

The pathogenesis of allergic bronchopulmonary aspergillosis (ABPA) involves specific cytokines secreted by lymphocytes in response to Aspergillus fumigatus (Af) allergens. To gain information about the lymphoproliferative response and cytokine production against a major Af allergen, Asp f 2, we studied Asp-f-2-specific T cell clones (TCCs) from ABPA patients. TCCs were stimulated with rAsp f 2, its deletion mutants, and synthetic peptides to identify the T cell epitope(s) and to understand cytokine production. PBMCs from four of five ABPA patients showed proliferation in response to Asp f 2. Three TCCs from one patient showed higher IL-5 secretion compared to IL-4 and IFN-gamma. Two TCCs from the second patient showed a mixed Th1/Th2 response, as evidenced by production of IL-4, IL-5, and IFN-gamma. An epitope from the N-terminal region of Asp f 2 induced only IL-5 secretion. High IL-5 secretion might explain the marked eosinophilia observed in ABPA patients.

Purified recombinant A. fumigatus allergens induce different responses in mice

Aspergillus fumigatus an opportunistic fungus is associated with a number of diseases in humans. Allergy resulting from exposure to the A. fumigatus allergens has been recognized frequently. The damage caused by the disease is very striking in patients with atopy and those with cystic fibrosis. Avoidance to exposure is not feasible because A. fumigatus spores are ubiquitously distributed in the environment. Hence, immunotherapeutic regimens in severe forms of A. fumigatus allergy may have a high potential. However, before such forms of therapy can be envisaged, it is essential to understand the immunopathogenesis. In the present study, we investigated the role of purified A. fumigatus allergens in the development of allergic asthma in mice. We have used four major recombinant A. fumigatus allergens in the murine model. Mice exposed to Asp f 1, f 3, and f 4 showed inflammatory changes in the lungs and airway hyperreactivity. The immune responses, including elevated serum IgE, enhanced eosinophils, recruitment in the peripheral blood and lungs, and expression of regulatory cytokines, are characteristic of a Th2 response. Asp f 6 demonstrated only a reduced response in these animals. The results suggest that the pathology induced by crude A. fumigatus extract results from the cumulative effects of the allergens and the individual responses varied considerably with different purified antigens.

Enhanced pulmonary allergic responses to Aspergillus in CCR2-/- mice

Allergic responses to Aspergillus species exacerbate asthma and cystic fibrosis. The natural defense against live Aspergillus fumigatus spores or conidia depends on the recruitment and activation of mononuclear and polymorphonuclear leukocytes, events that are dependent on chemotactic cytokines. In this study, we explored the relative contribution of the monocyte chemoattractant protein-1 receptor, CCR2, in the pulmonary response to A. fumigatus conidia. Following sensitization to soluble A. fumigatus Ags, mice lacking CCR2 due to targeted deletion were markedly more susceptible to the injurious effects of an intrapulmonary challenge with live conidia compared with mice that expressed CCR2 or CCR2+/+. CCR2-/- mice exhibited a major defect in the recruitment of polymorphonuclear cells, but these mice also had significantly more eosinophils and lymphocytes in bronchoalveolar lavage samples. CCR2-/- mice also had significant increases in serum levels of total IgE and whole lung levels of IL-5, IL-13, eotaxin, and RANTES compared with CCR2+/+ mice. Airway inflammation, hyper-responsiveness to spasmogens, and subepithelial fibrosis were significantly enhanced in CCR2-/- mice compared with CCR2+/+ mice after the conidia challenge. Thus, these findings demonstrate that CCR2 plays an important role in the immune response against A. fumigatus, thereby limiting the allergic airway inflammatory and remodeling responses to this fungus.

T cell vaccination in mice with invasive pulmonary aspergillosis

Aspergillus fumigatus, an opportunistic fungal pathogen, is responsible for multiple airway diseases of an allergic and a nonallergic nature. In a murine model of invasive pulmonary aspergillosis, resistance is associated with a decreased lung inflammatory pathology and the occurrence of an IL-12-dependent Th1-type reactivity that are both impaired by IL-4. In the present study we assess the ability of Aspergillus crude culture filtrate Ags and the recombinant allergen Asp f 2 to induce protective antifungal responses in mice with invasive pulmonary aspergillosis. Similar to what occurred upon nasal exposure to viable A. fumigatus conidia, treatment of immunocompetent mice with Aspergillus crude culture filtrate Ags resulted in the development of local and peripheral protective Th1 memory responses, mediated by Ag-specific CD4+ T cells producing IFN-gamma and IL-2 capable of conferring protection upon adoptive transfer to naive recipients. Protective Th1 responses could not be observed in mice deficient of IFN-gamma or IL-12 and did not occur in response to Asp f 2, which, on the contrary, elicited high level production of inhibitory IL-4. The results show that Ags of Aspergillus exist with the ability to induce both Th1- and Th2-type reactivity during infection, a finding that suggests a possible mechanism through which potentially protective immune responses are inhibited in mice with the infection. However, the occurrence of Th1-mediated resistance upon vaccination with Aspergillus crude culture filtrate Ags, suggests the existence of fungal Ags useful as a candidate vaccine against invasive pulmonary aspergillosis.

Fungal allergens and peptide epitopes

Fungal allergens represent a major cause of atopic disorders. Immunochemical and molecular characterization of fungal allergens has been hampered by the lack of pure proteins and to inherent variation among fungal proteins and in their poor yields. With the advent of molecular biology techniques, a number of allergens have been cloned, sequenced, and expressed from a variety of fungal species. The knowledge of the primary, secondary, and tertiary structures of these allergens, the immunodominant regions of these proteins, and their interaction with T and B-cell epitopes, results in better understanding of the molecular mechanisms of allergy and may provide avenues of immunologic intervention to treat patients. The present review deals with the current understanding of fungal allergen epitopes.

Intravenous injection of major and cryptic peptide epitopes of ribotoxin, Asp f 1 inhibits T cell response induced by crude Aspergillus fumigatus antigens in mice

Aspergillus fumigatus, a ubiquitous fungus, is implicated in the pathogenesis of a number of clinically different allergic diseases in man. Peptide-based immunotherapy may offer an alternative in patient care and management. The purpose of this study was to evaluate the role of T cell epitopes of A. fumigatus ribotoxin, Asp f 1 in inducing tolerance in mice exposed to A. fumigatus antigen. The epitope analysis in BALB/c mice using synthetic peptides of Asp f 1 demonstrated both cryptic and dominant epitopes detected from 42 through 54 and 155 through 167 aa, accordingly. Intravenous injection of these peptides markedly inhibited the response induced by the exposure to crude A. fumigatus extract in mice as evidenced by the in vitro interleukin-2 (IL-2) production and proliferation of T-lymphocytes. Cytokine transcription studies indicate that, when stimulated with the peptides in immunogenic conditions, the major peptide (aa 155-167) specific T cell clone produced only IFN-gamma, but not IL-4. The ability of both dominant and cryptic peptide epitopes of a single molecule to induce tolerance against the immune response to a multi-molecular allergen complex has significant implication for peptide-based immunotherapy.

Immunomodulatory Role of C10 Chemokine in a Murine Model of Allergic Bronchopulmonary Aspergillosis

The immunomodulatory role of the chemokine C10 was explored in allergic airway responses during experimental allergic bronchopulmonary aspergillosis (ABPA). The intratracheal delivery of Asperigillus fumigatus Ag into A. fumigatus-sensitized mice resulted in significantly increased levels of C10 within the bronchoalveolar lavage, and these levels peaked at 48 h after A. fumigatus challenge. In addition, C10 levels in BAL samples were greater than 5-fold higher than levels of other chemokines such as monocyte-chemoattractant protein-1, eotaxin, and macrophage-inflammatory protein-1α. From in vitro studies, it was evident that major pulmonary sources of C10 may have included alveolar macrophages, lung fibroblasts, and vascular smooth muscle cells. Experimental ABPA was associated with severe peribronchial eosinophilia, bronchial hyperresponsiveness, and augmented IL-13 and IgE levels. The immunoneutralization of C10 with polyclonal anti-C10 antiserum 2 h before the intratracheal A. fumigatus challenge significantly reduced the airway inflammation and hyperresponsiveness in this model of ABPA, but had no effect on IL-10 nor IgE levels. Taken together, these data suggest that C10 has a unique role in the progression of experimental ABPA.

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.

Aspergillus fumigatus antigen exposure results in pulmonary airway resistance in wild-type but not in IL-4 knockout mice

Inhalation of Aspergillus fumigatus, a ubiquitous fungus, results in the development of allergic bronchopulmonary aspergillosis, a disabling allergic lung disease. For better patient management early diagnosis is essential, and understanding of the immune mechanism is important in achieving this goal. Although animal model studies have contributed to the understanding of the disease mechanism, details on the immunopathogenesis are still lacking. In the present study, we have developed an allergic aspergillosis model in wild-type and IL-4 knockout mice and studied the immune and airway responses. The results indicate that the immune response, pulmonary pathology, and airway reactivity comparable to allergic bronchopulmonary aspergillosis are reproducible in wild mice. IL-4 knockout mice showed similar pulmonary pathology, but no increase in airway resistance, suggesting that IgE and hence IL-4 may be important in eliciting the airway response, while other factors may be involved in the inflammatory process.

Increased antigen-specific Th-2 response in allergic bronchopulmonary aspergillosis (ABPA) in patients with cystic fibrosis

The majority of patients with cystic fibrosis (CF) become colonized with Aspergillus fumigatus (A. fumigatus) in the lower respiratory tract, the prevalence being up to 60%. Between 1-11% of CF patients develop allergic bronchopulmonary aspergillosis (ABPA). Previous studies of ABPA in selected patients suffering from cystic fibrosis or atopic asthma have suggested a pathogenic role for antigen-specific "Th2-like" T lymphocytes. The aim of this study was to evaluate the quantitative importance of such Th2 cells, using improved techniques for measuring interleukin-4 (IL-4) and IL-5 secretion in unseparated peripheral blood mononuclear cell (PBMC) suspensions from CF patients with ABPA and from a control group without ABPA. Thus, 20 patients with CF, heavily colonized with A. fumigatus in the lower respiratory tract, were studied: 10 patients with ABPA, and 10 without. Unseparated PBMC were stimulated in vitro by A. fumigatus antigen and by an unrelated antigen (tetanus toxoid) as a control. After 6 days of stimulation, IL-4 and IL-5 (markers for Th2 cell activity) and interferon-gamma (IFN-gamma) (marker for Th1 cell activity) were quantified in the supernatants by enzyme-linked immunosorbent assay. PBMC from ABPA patients secreted significantly higher amounts of IL-4, i.e., 0.48 (0.15-0.8) ng/mL (median (range)), and IL-5, 37.64 (0.32-82.85) ng/mL, compared to secretions obtained in non-ABPA CF controls of 0.07 (0.04-0.16) ng/mL and 3.00 (0.10-5.09) ng/mL, respectively (P < 0.01 for both). IFN-gamma secretion was similar in the two groups, amounting to 21.5 (2.05-72.5) ng/mL in ABPA patients vs. 20.75 (1.80-54.0) ng/mL in non-ABPA patients (P = 0.47). No significant differences were obtained in the cytokine secretion induced by tetanus toxoid stimulation between the two groups. We conclude that ABPA in CF patients is associated with an antigen-specific, Th2-like T-cell immune response, as indicated by excessive secretion of IL-4 and IL-5.

Thymosin-alpha1 stimulates maturation of CD34+ stem cells into CD3+4+ cells in an in vitro thymic epithelia organ coculture model

The effect of thymosin-alpha1 on thymopoiesis is largely unknown. Thymosin is found in the cortical and medullary thymic epithelia, as well as in nurse cells; thus, it is hypothesized that thymosin may affect both early and late stage of thymocyte maturation. In this study, the effect of thymosin-alpha1 on thymopoiesis was determined by coculturing in vitro CD34+ stem cells (SC) with allogeneic cultured thymic epithelia fragments (CTEF) for 1-4 weeks and analyzing T-cell maturation by flow cytometry. Thymosin-alpha1 significantly enhanced the cell number (e.g., proliferation) of mononuclear cells obtained at 2 and 4 weeks of the SC-CTEF cocultures (P < 0.01 and < 0.05, respectively). In particular, thymosin-alpha1 stimulated expression of CD3+ cells at 3 and 4 weeks (P < 0.05). The predominant subpopulation increased by thymosin stimulation was single positive mature CD4+ cells, which was confirmed to occur within the SC-CTEF thymic organ tissue by laser confocal immunofluorescence microscopy. Thymosin stimulation tended to enhance IL-7 synthesis, critical cytokine in the maturation of thymocytes. In summary, this is the first study to demonstrate that thymosin-alpha1 enhanced thymopoiesis of CD34+ stem cells in humans using an in vitro model of differentiation using stem cells and cultured thymic epithelial fragments cocultures. Furthermore, the thymosin significantly increased expression of CD3+4+ T cells.

IgE down regulation and cytokine induction by Aspergillus antigens in human allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA), occurring primarily in patients with asthma or cystic fibrosis (CF), is a hypersensitivity reaction to Aspergillus fumigatus (Af), and is characterized by increased serum IgE levels and peripheral blood and pulmonary eosinophilia. We evaluated the IgE and cytokine profile in ABPA through enzyme-linked immunosorbent assay (ELISA), and evaluated eosinophil activity with the eosinophil peroxidase (EPO) assay. IgE and cytokines were measured in supernatants from cultures of peripheral blood mononuclear cells (PBMC) from three subject groups: ABPA patients, patients with asthma, and healthy individuals. All cultures for the three subject groups were studied in the presence and absence of two purified Af antigens (the 35-kD antigen and heat shock protein 1). We found that increased in vitro levels of IgE in unstimulated PBMC culture supernatants correlated significantly with serum IgE concentrations in ABPA patients. We measured a decrease in IgE levels of up to 75% of baseline values in supernatants from PBMC cultured with Af antigens. Interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) concentrations in cultures with Af were increased in ABPA, whereas concentrations of IL-4 did not differ in the three subject groups. An inverse relation was noted between the changes in IgE and IFN-gamma measured in 4 of 5 ABPA patients. The PBMC supernatants also promoted EPO activity in purified eosinophils from ABPA patients, and to a lesser extent in purified eosinophils from healthy subjects. These results show that the 35-kD antigen and HSP1 from Af downregulate IgE in vitro but are capable of inducing eosinophilia in ABPA. Further studies could result in the characterization of epitopes leading to these disparate effects. An identification of the IgE-down-regulating epitopes in Af antigens might have therapeutic significance.