Blood basophils from cystic fibrosis patients with allergic bronchopulmonary aspergillosis are primed and hyper-responsive to stimulation by aspergillus allergens

Laboratory biomarkers in the diagnosis and follow-up of treatment of allergic bronchopulmonary aspergillosis in cystic fibrosis

Allergic bronchopulmonary aspergillosis (ABPA), a severe inflammatory respiratory disease, is caused by a hypersensitivity reaction to the colonization of the airways with Aspergillus fumigatus. It is most often described in patients with asthma or cystic fibrosis. The diagnosis of ABPA is based on a combination of clinical, radiological, and immunological findings that have been included in different diagnostic criteria over the years. In this paper, we review the biomarkers included in these diagnostic criteria and novel research biomarkers that may be used in the diagnosis and treatment follow-up of ABPA in cystic fibrosis.

Progress and challenges in fungal lung disease in cystic fibrosis

PURPOSE OF REVIEW

This review is an overview of the recent progress made for the diagnosis and understanding of fungal lung disease in people with cystic fibrosis (CF), with a focus on Aspergillus fumigatus , the most common filamentous fungus in the CF airway. Currently, the longstanding question of the clinical significance of Aspergillus fumigatus and other fungi in CF respiratory cultures, in the absence of allergy, remains. Clinical criteria and biomarkers are needed to classify fungal lung disease and determine who may warrant therapy.

RECENT FINDINGS

Several retrospective and prospective studies have described the prevalence of A. fumigatus and other fungi in the CF lung and factors contributing to the changes in fungal epidemiology. Selective fungus culture testing for the detection of fungi in CF sputa has been well studied, yet a standardized fungus culture protocol has yet to be defined. Culture-independent molecular studies and other fungal diagnostic testing have been conducted in the CF population, leading to efforts to better understand the clinical role of these tests. Recent works have aimed to determine whether chronic A. fumigatus colonization is associated with lung disease progression measured by FEV 1 percentage predicted, structural lung disease, lung clearance index and respiratory quality-of-life. However, the existing knowledge gaps remain: definition of a fungal respiratory infection, the association between fungal infection and clinical outcomes, and indications for antifungal therapy.

SUMMARY

Significant progress has been made for the detection and diagnosis of fungal lung disease. Yet, the role and impact of A. fumigatus and other fungal infections on respiratory health in people with CF remains to be determined.

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.

Biomarkers for the Diagnosis of Allergic Bronchopulmonary Aspergillosis in Cystic Fibrosis: A Systematic Review and Meta-Analysis

BACKGROUND

Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity reaction to Aspergillus fumigatus and impacts 10% of individuals with cystic fibrosis (CF). A diagnosis of ABPA is challenging to establish in CF owing to overlapping clinical and radiologic features with CF lung disease. Recent studies have identified blood tests, imaging, and other biomarkers that may be useful for diagnosis.

OBJECTIVE

To summarize biomarkers that can aid in the diagnosis of ABPA in CF patients and to quantify their diagnostic accuracy through meta-analysis.

METHODS

We searched MEDLINE, EMBASE, and the Cochrane Controlled Register of Trials and included studies that used a laboratory technique or imaging modality in CF patients diagnosed with ABPA. Pooled sensitivity and specificity were calculated using a hierarchical summary receiver operating characteristic model.

RESULTS

We identified 791 articles, of which 29 met our eligibility criteria and 9 were included in the meta-analysis. Hyperattenuating mucus on computed tomography (CT) scan (n = 3 studies; pooled sensitivity 62% and specificity 92%) and serum specific immunoglobulin E against recombinant Aspergillus funigatus antigens f4 (n = 6; 69%, 89%) and f6 (n = 6; 39%, 97%) demonstrated high specificity. Based on single studies, serum thymus and activation regulated chemokine (92%, 94%), stimulated basophil expression of CD203c (94%, 74%), the inverted mucoid impaction signal on magnetic resonance imaging (94%, 100%), and skin prick test with recombinant Aspergillus fumigatus f4 and/or f6 (100%, 100%) showed high sensitivity and specificity.

CONCLUSIONS

Recent studies have found promising biomarkers for diagnosing ABPA in CF. Further research is needed to improve our understanding of their utility in diagnosis and disease monitoring.

Anaphylaxis and anaphylactoid reactions associated with the insertion of peripherally inserted central catheters: A multiyear comparative retrospective cohort study

OBJECTIVE

Peripherally inserted central catheters (PICCs) are a mainstay of nonpermanent vascular access devices. In this study, we assessed patients displaying anaphylaxis or anaphylactoid reactions to the PowerPICC SOLO and Groshong PICC (Bard Access Systems) using the Sherlock tip locating system (TLS).

METHODS

Patients from 2 tertiary-care hospitals were systematically monitored over 4 years for adverse events following the insertion of a PICC using the Sherlock TLS. Insertion data were also collected using the BioFlo PICC (Angiodynamics)from a third hospital site and from The Ottawa Hospital over 4 years as an additional comparator. Three definitions of anaphylaxis and anaphylactoid reactions were utilized, and the Cohen κ was used to assess interrater agreement. Analysis of reactions among the patient cohorts was performed using the χ2 test with Yates correction or the Fisher exact test as appropriate.

RESULTS

Among 8,257 insertions using the TLS PICCs, 37 potential reactions (0.45%) were recorded. Using specific definitions for anaphylaxis or anaphylactoid reactions, 54.1%-91.9% met criteria. Comparator populations using data from Calgary (n = 491) and Ottawa (n = 7,889) using the BioFlo PICC insertion found no reactions. Anaphylactic or anaphylactoid reactions were significantly associated with the PowerPICC SOLO and Groshong PICC with the TLS compared to the BioFlo PICC (P < .0001) across all definitions. The largest subset of patients experiencing adverse reactions had cystic fibrosis (CF) (n = 4, 10.8%).

CONCLUSION

Our study results demonstrate significant adverse events associated with the PowerPICC SOLO and Groshong PICC using the Sherlock TLS inserted across a range of patient populations. The incidence rate of anaphylaxis or anaphylactoid reactions in the CF population at our center is significantly higher than in non-CF patients (P < .001).

Immunomodulation in Cystic Fibrosis: Why and How?

Cystic fibrosis (CF) lung disease is characterized by unconventional mechanisms of inflammation, implicating a chronic immune response dominated by innate immune cells. Historically, therapeutic development has focused on the mutated cystic fibrosis transmembrane conductance regulator (CFTR), leading to the discovery of small molecules aiming at modulating and potentiating the presence and activity of CFTR at the plasma membrane. However, treatment burden sustained by CF patients, side effects of current medications, and recent advances in other therapeutic areas have highlighted the need to develop novel disease targeting of the inflammatory component driving CF lung damage. Furthermore, current issues with standard treatment emphasize the need for directed lung therapies that could minimize systemic side effects. Here, we summarize current treatment used to target immune cells in the lungs, and highlight potential benefits and caveats of novel therapeutic strategies.

The utility of the basophil activation test in differentiating asthmatic subjects with and without allergic bronchopulmonary aspergillosis

BACKGROUND

Asthma with Aspergillus sensitisation (ASA) and allergic bronchopulmonary aspergillosis (ABPA) are distinct clinical conditions, with different management strategies.

OBJECTIVE

To determine the utility of the basophil activation test (BAT) in differentiating between asthmatic subjects with and without ABPA.

METHODS

We performed the BAT using flow cytometry for the basophil activation markers CD63, CD193, and CD203c in consecutive subjects with unsensitised asthma (UA), ASA and ABPA. The BAT was performed unstimulated (baseline) and after stimulation with peanut and Aspergillus fumigatus antigens. Stimulation indices (SI) for CD63, CD193 and CD203c were compared between the study groups.

RESULTS

We enrolled 82 (UA [n = 25], ASA [n = 25], ABPA [n = 32]) subjects. Only those subjects without peanut sensitisation on serological testing were included in further analyses (n = 50). The receiver operating characteristic analysis of SI for CD63, CD193 and CD203c for the diagnosis of ABPA vs other asthmatics (UA and ASA) showed an area under the curve of 0.577, 0.317 and 0.625, respectively. The SI CD203c at a cut-off of 1.2 (sensitivity 50.0%, specificity 88.9%) and the SI CD63 at a cut-off of 1.3 (sensitivity 42.9%, specificity 91.7%) also had limited utility for the diagnosis of ABPA.

CONCLUSION

The BAT cannot be used as a diagnostic test in distinguishing ABPA complicating asthma from ASA and UA.

Current Approach in the Diagnosis and Management of Allergic Bronchopulmonary Aspergillosis in Children With Cystic Fibrosis

Allergic bronchopulmonary aspergillosis (ABPA) is a complex pulmonary disorder characterized by a hypersensitivity reaction to Aspergillus fumigatus, and almost always seen in patients with cystic fibrosis (CF) and asthma. Fungal hyphae leads to an ongoing inflammation in the airways that may result in bronchiectasis, fibrosis, and eventually loss of lung function. Despite the fact that ABPA is thought to be more prevalent in CF than in asthma, the literature on ABPA in CF is more limited. The diagnosis is challenging and may be delayed because it is made based on a combination of clinical features, and radiologic and immunologic findings. With clinical deterioration of a patient with CF, ABPA is important to be kept in mind because clinical manifestations mimic pulmonary exacerbations of CF. Early diagnosis and appropriate treatment are important in preventing complications related to ABPA. Treatment modalities involve the use of anti-inflammatory agents to suppress the immune hyperreactivity and the use of antifungal agents to reduce fungal burden. Recently, in an effort to treat refractory patients or to reduce adverse effects of steroids, other treatment options such as monoclonal antibodies have started to be used. Intensive research of these new agents in the treatment of children is being conducted to address insufficient data.

The myriad challenges of respiratory fungal infection in cystic fibrosis

Fungal infection in cystic fibrosis (CF) is a recognized challenge, with many areas requiring further investigation. Consensus definitions exist for allergic bronchopulmonary aspergillus in CF, but the full scope of clinically relevant non-allergic fungal disease in CF-asymptomatic colonization, transient or chronic infection localized to endobronchial mucus plugs or airway tissue, and invasive disease-is yet to be clearly defined. Recent advances in mycological culture and non-culture identification have expanded the list of both potential pathogens and community commensals in the lower respiratory tract. Here we aim to outline the current understanding of fungal presence in the CF respiratory tract, risk factors for acquiring fungi, host-pathogen interactions that influence the role of fungi from bystander to pathogen, advances in the diagnostic approaches to isolating and identifying fungi in CF respiratory samples, challenges of classifying clinical phenotypes of CF patients with fungi, and current treatment approaches. Development and validation of biomarkers characteristic of different fungal clinical phenotypes, and controlled trials of antifungal agents in well-characterized target populations, remain central challenges to surmount and goals to be achieved.

QFMatch: multidimensional flow and mass cytometry samples alignment

Part of the flow/mass cytometry data analysis process is aligning (matching) cell subsets between relevant samples. Current methods address this cluster-matching problem in ways that are either computationally expensive, affected by the curse of dimensionality, or fail when population patterns significantly vary between samples. Here, we introduce a quadratic form (QF)-based cluster matching algorithm (QFMatch) that is computationally efficient and accommodates cases where population locations differ significantly (or even disappear or appear) from sample to sample. We demonstrate the effectiveness of QFMatch by evaluating sample datasets from immunology studies. The algorithm is based on a novel multivariate extension of the quadratic form distance for the comparison of flow cytometry data sets. We show that this QF distance has attractive computational and statistical properties that make it well suited for analysis tasks that involve the comparison of flow/mass cytometry samples.

Fungal Pathogens in CF Airways: Leave or Treat?

Chronic airway infection plays an essential role in the progress of cystic fibrosis (CF) lung disease. In the past decades, mainly bacterial pathogens, such as Pseudomonas aeruginosa, have been the focus of researchers and clinicians. However, fungi are frequently detected in CF airways and there is an increasing body of evidence that fungal pathogens might play a role in CF lung disease. Several studies have shown an association of fungi, particularly Aspergillus fumigatus and Candida albicans, with the course of lung disease in CF patients. Mechanistically, in vitro and in vivo studies suggest that an impaired immune response to fungal pathogens in CF airways renders them more susceptible to fungi. However, it remains elusive whether fungi are actively involved in CF lung disease pathologies or whether they rather reflect a dysregulated airway colonization and act as microbial bystanders. A key issue for dissecting the role of fungi in CF lung disease is the distinction of dynamic fungal-host interaction entities, namely colonization, sensitization or infection. This review summarizes key findings on pathophysiological mechanisms and the clinical impact of fungi in CF lung disease.

Fungal Contaminants in Drinking Water Regulation? A Tale of Ecology, Exposure, Purification and Clinical Relevance

Microbiological drinking water safety is traditionally monitored mainly by bacterial parameters that indicate faecal contamination. These parameters correlate with gastro-intestinal illness, despite the fact that viral agents, resulting from faecal contamination, are usually the cause. This leaves behind microbes that can cause illness other than gastro-intestinal and several emerging pathogens, disregarding non-endemic microbial contaminants and those with recent pathogenic activity reported. This white paper focuses on one group of contaminants known to cause allergies, opportunistic infections and intoxications: Fungi. It presents a review on their occurrence, ecology and physiology. Additionally, factors contributing to their presence in water distribution systems, as well as their effect on water quality are discussed. Presence of opportunistic and pathogenic fungi in drinking water can pose a health risk to consumers due to daily contact with water, via several exposure points, such as drinking and showering. The clinical relevance and influence on human health of the most common fungal contaminants in drinking water is discussed. Our goal with this paper is to place fungal contaminants on the roadmap of evidence based and emerging threats for drinking water quality safety regulations.

Developments in the diagnosis and treatment of allergic bronchopulmonary aspergillosis

INTRODUCTION

Allergic bronchopulmonary aspergillosis (ABPA) is a complex pulmonary disorder characterized by recurrent episodes of wheezing, fleeting pulmonary opacities and bronchiectasis. It is the most prevalent of the Aspergillus disorders with an estimated five million cases worldwide. Despite six decades of research, the pathogenesis, diagnosis and treatment of this condition remains controversial. The International Society for Human and Animal Mycology has formed a working group to resolve the controversies around this entity. In the year 2013, this group had proposed new criteria for diagnosis and staging, and suggested a treatment protocol for the management of this disorder. Since then, several pieces of new evidence have been published in the investigation and therapeutics of this condition. Areas covered: A non-systematic review of the available literature was performed. We summarize the current evidence in the evaluation and treatment of this enigmatic disorder. We suggest modifications to the existing criteria and propose a new scoring system for the diagnosis of ABPA. Expert commentary: All patients with asthma and cystic fibrosis should routinely be screened for ABPA using A. fumigatus-specific IgE levels. Glucocorticoids should be used as the first-line of therapy in ABPA, and itraconazole reserved in those with recurrent exacerbations and glucocorticoid-dependent disease.

Prevalence of Aspergillus sensitization and allergic bronchopulmonary aspergillosis in cystic fibrosis: systematic review and meta-analysis

BACKGROUND

The prevalence of Aspergillus sensitization (AS) and allergic bronchopulmonary aspergillosis (ABPA) in cystic fibrosis (CF) has been varyingly reported. The aim of this systematic review was to estimate the overall prevalence of AS/ABPA in CF.

METHODS

We searched the PubMed and EmBase databases for studies reporting the prevalence of AS/ABPA in CF. We calculated the proportion with 95% confidence interval (CI) to assess the prevalence of AS and ABPA in the individual studies and then pooled the results using a random effects model. Statistical heterogeneity was assessed using the I2 test while publication bias was assessed using both graphical and statistical methods.

RESULTS

Our search yielded 64 eligible studies. The pooled prevalence of AS was 39.1% (95% CI: 33.3-45.1) and was higher with skin test compared to specific IgE (43.8% vs. 32.8%, P = 0.002); however, the prevalence did not vary with the type of skin test used (intradermal or percutaneous). The prevalence of ABPA was 8.9% (95% CI: 7.4-10.7) and was higher in adults as compared to children (10.1% vs. 8.9%, P < 0.0001). There was a wide variation in the criteria used for diagnosing ABPA. Almost 50% (12/23) of the publications after 2004 used criteria other than the CF foundation criteria for diagnosing ABPA. There was significant statistical heterogeneity and evidence of publication bias.

CONCLUSIONS

There is a high prevalence of AS and ABPA in patients with CF. Despite six decades of research, there is still a need to adopt uniform methodology and criteria for the diagnosis of AS/ABPA.

Allergic Bronchopulmonary Aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA), a progressive fungal allergic lung disease, is a common complication of asthma or cystic fibrosis. Although ABPA has been recognized since the 1950s, recent research has underscored the importance of Th2 immune deviation and granulocyte activation in its pathogenesis. There is also strong evidence of widespread under-diagnosis due to the complexity and lack of standardization of diagnostic criteria. Treatment has long focused on downregulation of the inflammatory response with prolonged courses of oral glucocorticosteroids, but more recently concerns with steroid toxicity and availability of new treatment modalities has led to trials of oral azoles, inhaled amphotericin, pulse intravenous steroids, and subcutaneously-injected anti-IgE monoclonal antibody omalizumab, all of which show evidence of efficacy and reduced toxicity.

Animal Models of Cystic Fibrosis Pathology: Phenotypic Parallels and Divergences

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The resultant characteristic ion transport defect results in decreased mucociliary clearance, bacterial colonisation, and chronic neutrophil-dominated inflammation. Much knowledge surrounding the pathophysiology of the disease has been gained through the generation of animal models, despite inherent limitations in each. The failure of certain mouse models to recapitulate the phenotypic manifestations of human disease has initiated the generation of larger animals in which to study CF, including the pig and the ferret. This review will summarise the basic phenotypes of three animal models and describe the contributions of such animal studies to our current understanding of CF.

Earth Mover's Distance (EMD): A True Metric for Comparing Biomarker Expression Levels in Cell Populations

Changes in the frequencies of cell subsets that (co)express characteristic biomarkers, or levels of the biomarkers on the subsets, are widely used as indices of drug response, disease prognosis, stem cell reconstitution, etc. However, although the currently available computational “gating” tools accurately reveal subset frequencies and marker expression levels, they fail to enable statistically reliable judgements as to whether these frequencies and expression levels differ significantly between/among subject groups. Here we introduce flow cytometry data analysis pipeline which includes the Earth Mover’s Distance (EMD) metric as solution to this problem. Well known as an informative quantitative measure of differences between distributions, we present three exemplary studies showing that EMD 1) reveals clinically-relevant shifts in two markers on blood basophils responding to an offending allergen; 2) shows that ablative tumor radiation induces significant changes in the murine colon cancer tumor microenvironment; and, 3) ranks immunological differences in mouse peritoneal cavity cells harvested from three genetically distinct mouse strains.

Blood basophil activation is a reliable biomarker of allergic bronchopulmonary aspergillosis in cystic fibrosis

The diagnosis of cystic fibrosis (CF) patients with allergic bronchopulmonary aspergillosis (ABPA) is clinically challenging, due to the absence of an objective biological test. Since blood basophils play a major role in allergic responses, we hypothesised that changes in their surface activation pattern discriminate between CF patients with and without ABPA.

We conducted a prospective longitudinal study (Stanford cohort) comparing basophil activation test CD203c levels by flow cytometry before and after activation withAspergillus fumigatusallergen extract or recombinantAspf1 in 20 CF patients with ABPA (CF-ABPA) and in two comparison groups: CF patients withA. fumigatuscolonisation (AC) but without ABPA (CF-AC; n=13) and CF patients without either AC or ABPA (CF; n=12). Patients were tested every 6 months and when ill with pulmonary exacerbation. We also conducted cross-sectional validation in a separate patient set (Dublin cohort).

Basophil CD203c surface expression reliably discriminated CF-ABPA from CF-AC and CF over time. Ex vivostimulation withA. fumigatusextract or recombinantAspf1 produced similar results within the Stanford (p<0.0001) and the Dublin cohorts. CF-ABPA patients were likelier to have elevated specific IgE toA. fumigatusand were less frequently co-infected withStaphylococcus aureus.

Basophil CD203c upregulation is a suitable diagnostic and stable monitoring biomarker of ABPA in CF.

The basophil surface marker CD203c identifies Aspergillus species sensitization in patients with cystic fibrosis

BACKGROUND

Colonization by Aspergillus fumigatus in patients with cystic fibrosis (CF) can cause A fumigatus sensitization and/or allergic bronchopulmonary aspergillosis (ABPA), which affects pulmonary function and clinical outcomes. Recent studies show that specific allergens upregulate the surface-expressed basophil marker CD203c in sensitized subjects, a response that can be readily measured by using flow cytometry.

OBJECTIVE

We sought to identify A fumigatus sensitization in patients with CF by using the basophil activation test (BAT).

METHODS

Patients with CF attending Beaumont Hospital were screened for study inclusion. BAT was used to identify A fumigatus sensitization. Serologic (total and A fumigatus-specific IgE), pulmonary function, and body mass index measurements were performed.

RESULTS

The BAT discriminates A fumigatus-sensitized from nonsensitized patients with CF. Persistent isolation of A fumigatus in sputum is a significant risk factor for A fumigatus sensitization. Levels of the A fumigatus-stimulated basophil activation marker CD203c inversely correlated with pulmonary function and body mass index in A fumigatus-sensitized but not nonsensitized patients with CF. Total and A fumigatus-specific IgE, but not IgG, levels are increased in A fumigatus-sensitized patients with CF and ABPA when compared with those in A fumigatus-sensitized and nonsensitized patients with CF without ABPA. Itraconazole treatment did not affect A fumigatus sensitization.

CONCLUSION

Combining the BAT with routine serologic testing allows classification of patients with CF into 3 groups: nonsensitized, A fumigatus-sensitized, and ABPA. Accurate and prompt identification of A fumigatus-associated clinical status might allow early and targeted therapeutic intervention, potentially improving clinical outcomes.

Diagnosis of allergic bronchopulmonary aspergillosis: a case-based approach

Allergic bronchopulmonary aspergillosis is a pulmonary disease occurring in patients with asthma or cystic fibrosis, consequent to a dysregulated immune response to inhaled Aspergillus conidia. The usual presentation is with poorly controlled asthma. Patients may also present with expectoration of mucus plugs, hemoptysis, constitutional symptoms and radiological opacities. Patients may experience smoldering lung destruction despite well-controlled asthma. With emerging data, the diagnostic criteria transcribed by an International Expert Committee in 2013 are the latest evidence-based guidelines. Herein, we utilize a case-based approach to elaborate on the diagnosis of this disease. The review intends to provide a lucid understanding of the diagnostic process for the expert as well as the primary physician, involved in management of this enigmatic disorder.

Dynamic quantification of antigen molecules with flow cytometry

Traditional methods for estimating the number of expressed molecules, based on the detection of target antigens bound with fluorescently labeled antibodies, assume that the antigen-antibody reaction reaches equilibrium. A calibration procedure is used to convert the intensity of the fluorescence signal to the number of target molecules. Along with the different limitations of every calibration system, this substantially limits the applicability of the traditional approaches especially in the case of low affinity antibodies. We address this problem here with studies in which we demonstrate a new approach to the antigen molecule quantification problem. Instead of using a static calibration system, we analyzed mean fluorescence values over time by flow cytometry during antibody-antigen binding. Experimental data obtained with an LSRII cytometer were fitted by a diffusion-reaction mathematical model using the Levenberg-Marquardt nonlinear least squares curve-fitting algorithm in order to obtain the number of target antigen molecules per cell. Results were compared with the Quanti-BRITE calibration system. We conclude that, instead of using experiment-specific calibration, the value of the binding rate constant for each particular antibody-antigen reaction can be used to quantify antigen molecules with flow cytometry. The radius of CD8 antibody molecule binding site was found, that allows recalculating the binding rate constant for other conditions (different sizes of reagent molecules, fluorescent label, medium viscosity and temperature). This approach is independent of specially prepared calibration beads, antibody reagents and the specific dye and can be applied to both low and high affinity antibodies, under both saturating and non-saturating binding conditions. The method was demonstrated on a human blood sample dataset investigating CD8α antigen on T cells in stable binding conditions.

Antibiotic management of lung infections in cystic fibrosis. II. Nontuberculous mycobacteria, anaerobic bacteria, and fungi

Airway infections are a key component of cystic fibrosis (CF) lung disease. Whereas the approach to common pathogens such as Pseudomonas aeruginosa is guided by a significant body of evidence, other infections often pose a considerable challenge to treating physicians. In Part I of this series on the antibiotic management of difficult lung infections, we discussed bacterial organisms including methicillin-resistant Staphylococcus aureus, gram-negative bacterial infections, and treatment of multiple bacterial pathogens. Here, we summarize the approach to infections with nontuberculous mycobacteria, anaerobic bacteria, and fungi. Nontuberculous mycobacteria can significantly impact the course of lung disease in patients with CF, but differentiation between colonization and infection is difficult clinically as coinfection with other micro-organisms is common. Treatment consists of different classes of antibiotics, varies in intensity, and is best guided by a team of specialized clinicians and microbiologists. The ability of anaerobic bacteria to contribute to CF lung disease is less clear, even though clinical relevance has been reported in individual patients. Anaerobes detected in CF sputum are often resistant to multiple drugs, and treatment has not yet been shown to positively affect patient outcome. Fungi have gained significant interest as potential CF pathogens. Although the role of Candida is largely unclear, there is mounting evidence that Scedosporium species and Aspergillus fumigatus, beyond the classical presentation of allergic bronchopulmonary aspergillosis, can be relevant in patients with CF and treatment should be considered. At present, however there remains limited information on how best to select patients who could benefit from antifungal therapy.

Fungi in the cystic fibrosis lung: bystanders or pathogens?

Improvement to the life expectancy of people with cystic fibrosis (PWCF) brings about novel challenges including the need for evaluation of the role of fungi in the cystic fibrosis (CF) lung. To determine if such organisms represent bystanders or pathogens affecting clinical outcomes we review the existing knowledge from a clinical, biochemical, inflammatory and immunological perspective. The prevalence and importance of fungi in the CF airway has likely been underestimated with the most frequently isolated filamentous fungi being Aspergillus fumigatus and Scedosporium apiospermum and the major yeast Candida albicans. Developing non-culture based microbiological methods for fungal detection has improved both our classification and understanding of their clinical consequences including localized, allergic and systemic infections. Cross-kingdom interaction between bacteria and fungi are discussed as is the role of biofilms further affecting clinical outcome. A combination of host and pathogen-derived factors determines if a particular fungus represents a commensal, colonizer or pathogen in the setting of CF. The underlying immune state, disease severity and treatment burden represent key host variables whilst fungal type, form, chronicity and virulence including the ability to evade immune recognition determines the pathogenic potential of a specific fungus at a particular point in time. Further research in this emerging field is warranted to fully elucidate the spectrum of disease conferred by the presence of fungi in the CF airway and the indications for therapeutic interventions.

The use of biological agents for the treatment of fungal asthma and allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is a virulent manifestation of the Th2 asthma endotype that includes asthma with fungal sensitization, raising the feasibility of biological therapies targeting Th2 pathway molecules or cells. The first molecule amenable to clinical intervention with a biological was IgE. Omalizumab, a humanized monoclonal antibody (Mab), targets the same epitope on the IgE CH3 region that binds to and crosslinks high-affinity receptors on mast cells and basophils, thereby initiating the allergic inflammatory cascade. Omalizumab is licensed for allergic asthma and has been beneficial in uncontrolled studies of ABPA, reducing exacerbations and steroid requirements. Trials of several Mabs directed against the Th2 cytokine IL-5 show clinical benefit in patients with a severe refractory eosinophilic asthma phenotype, while a Mab against IL-13 is effective in asthma patients with a Th2-high endotype. Immunodulation is also feasible with small molecule biologicals, such as antisense oligodeoxynucleotides and cholecalciferol. Controlled trials of Th2-inhibiting biologicals in patients with ABPA and severe asthma with fungal sensitization appear warranted.