Cystic fibrosis--immunological reactions to A. fumigatus and common allergens

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.

Antibody testing in aspergillosis--quo vadis?

Humans are constantly exposed to airborne Aspergillus spores. Most develop Aspergillus-specific antibodies by adulthood. Persons with chronic lung disease or Aspergillus airway colonization often have raised levels of Aspergillus-specific immunoglobululin G (IgG). It is not known whether this signifies an increased risk of future aspergillosis.Chronic and allergic forms of pulmonary aspergillosis are estimated to affect over three million people worldwide. Antibody testing is central to diagnosis of these conditions, with raised Aspergillus-specific IgG in chronic pulmonary aspergillosis and raised Aspergillus-specific IgE in allergic aspergillosis. Antibody levels are also used to monitor treatment response in these syndromes. Acute invasive disease is less common. There is a more limited role for antibody testing in this setting as immunosuppression often results in delayed or absent antibody response.Many methods exist to detect Aspergillus-specific antibodies, but there are limited published data regarding comparative efficacy and reproducibility. We discuss the comparative merits of the available tests in the various clinical settings and their suitability for use in the resource-poor settings where the majority of cases of aspergillosis are thought to occur. We summarize the gaps in existing knowledge and opportunities for further study that could allow optimal use of antibody testing in this field.

Cystic fibrosis, atopy, asthma and ABPA

The role of atopy on cystic fibrosis (CF) progression remains unclear but evidence suggests that it may influence the appearance of co-morbid conditions such as CF asthma or allergic bronchopulmonary aspergillosis (ABPA). Recognising asthma in patients with CF is not always easy but the identification of atopic markers favours the diagnosis. Physicians should be aware of this fact in order to achieve a better control of respiratory symptoms in patients with CF. Bronchial mucosa inflammation and abnormal mucus predispose to mould colonisation. These patients are at higher risk of allergic sensitisation, especially when atopic susceptibility is present. In the particular case of A. fumigatus, allergic sensitisation precedes ABPA development, which occurs in up to 10% of CF patients. Progression of lung function deterioration is most strikingly pronounced in patients with ABPA. Therefore, sensitisation with A. fumigatus should be regularly tested in patients with CF, especially those at higher risk. Recombinant allergens constitute an important advance in differentiating Aspergillus sensitisation from ABPA itself.

The role of allergy in manifestations of respiratory disease in adult cystic fibrosis

BACKGROUND

Variability is present in the expression of the clinical phenotype in cystic fibrosis (CF). Part of this variability may be explained by the coexistence of allergy in CF.

OBJECTIVE

To determine the rate of allergy in adult CF and evaluate the association between allergy and the manifestations of upper and lower airway disease.

METHODS

We performed a cross-sectional study of consecutive patients enrolled in a university hospital adult CF clinic. Allergen specific IgE was determined by radioallergosorbent and skin prick tests to common aeroallergens. We characterized features of upper and lower airway disease by clinical evaluation of rhinitis and spirometry before allergy testing.

RESULTS

The study population consisted of 55 patients. Allergen specific IgE was present to at least 1 aeroallergen in 67% by skin prick testing and 80% by radioallergosorbent testing. Rhinitis occurred in 50% of the population and was associated with immediate-type hypersensitivity to aeroallergens other than molds. The frequency of rhinitis increased when there was sensitization to a greater number of aeroallergens and rarely occurred in the absence of allergic sensitization. There was no detectable difference in lung function between those with and without allergic sensitization.

CONCLUSIONS

Immediate-type hypersensitivity to aeroallergens commonly occurs in adult CF. The coexistence of allergy in CF is associated with clinical features of rhinitis. Because allergic manifestations of CF warrant appropriate therapy, individuals with CF should be evaluated for coexistent allergy.

Recurrence of allergic bronchopulmonary aspergillosis in the posttransplant lungs of a cystic fibrosis patient

Cystic fibrosis (CF) is an autosomal recessive disease of exocrine origin. Allergic bronchopulmonary aspergillosis (ABPA) is an immunologic disorder caused by colonization of the airways with Aspergillus fumigatus. A fumigatus has been cultured from posttransplant lungs in CF patients. Colonization of posttransplant lung with Aspergillus is a recognized phenomenon. In this case report, however, we present a patient who developed ABPA both before and after lung transplant. This patient meets the criteria for ABPA based on serologic results. ABPA may be a complication in post-CF lung transplant patients and serologic analysis should be considered when eosinophilia and pulmonary infiltrates or decline in lung function occurs.

Allergic bronchopulmonary aspergillosis in patients with cystic fibrosis

In order to determine the incidence of allergic bronchopulmonary aspergillosis (ABPA) in patients with cystic fibrosis (CF), we reviewed the records of 236 patients followed up at the Duke CF Center. Sixty patients (25 percent) had colonies of Aspergillus fumigatus. These patients were older and had more severe disease as assessed by lower Shwachman-Kulczycki (S-K) scores than the patients who did not have evidence of A fumigatus. In 15 of the patients with A fumigatus (6.5 percent of the total population), the diagnosis was ABPA. Age and S-K scores were not significantly different from those of the patients with A fumigatus without ABPA. Diagnostic features of the affected patients included wheezing refractory to bronchodilator therapy, persistent pulmonary infiltrates, peripheral eosinophilia, positive skin reactivity to an A fumigatus antigen and elevated total serum IgE levels. Steroid therapy was started for all patients, and clinical improvement was noted within 1 month as evidenced by decreased symptoms and weight gain. Chest x-ray films usually showed improvement. Vital capacity improved in all but two patients. Total IgE did not consistently decrease in response to therapy. Although the diagnosis of ABPA may be difficult to establish, ABPA commonly is associated with CF. Most patients respond to steroid therapy; however, the effect of therapy on the course of the disease is difficult to assess.

Immunodiagnosis of aspergillosis

Aspergillus species are ubiquitous fungi and have been implicated as the causative agents of a variety of lung disorders in humans. These disorders include allergic, saprophytic, and systemic manifestations. The allergic disorders mainly affect atopic persons, and invasive or systemic diseases affect immunosuppressed individuals. Immunodiagnosis can help the practitioner diagnose these diseases. Demonstration of circulating antibodies is a useful criterion, but the lack of dependable and standardized antigens is a limiting factor in the diagnosis of most Aspergillus-induced diseases. Despite this limitation, however, immunodiffusion and enzyme-linked immunosorbent assays have been widely used for the detection of antibodies in the sera of patients with aspergillosis. Similarly, crude and semipurified antigens are being used to demonstrate skin hypersensitivity in patients, and several methods have been useful in the detection of antigenemia in patients with invasive aspergillosis. With a growing number of reports on the incidence of aspergillosis and an increase in the number of immunosuppressed individuals in the population, more rapid methods and more reliable reagents for immunodiagnosis are needed. With recent attempts at obtaining reliable reagents for through hybridoma technology and molecular biological techniques, substantial progress toward efficient immunodiagnosis may be achieved.

The relationship between atopy and cystic fibrosis

The incidence and clinical significance of allergy in cystic fibrosis have been discussed. There is little evidence that the high prevalence of positive allergy skin tests in CF is a clinical manifestation of a hypersensitivity lung disease complicating the primary pulmonary disorder, except in the special case of allergic bronchopulmonary aspergillosis. The lung disease of CF appears to be caused by excessive bronchial secretions and recurrent infection that are the result of abnormal ion transport across the apical membrane of the respiratory epithelial cell. There are two important questions concerning the allergic reactions: Are they clinically significant, and, why do they occur? The former question is partly resolved by the data presented, although well-controlled studies of intervention would help to resolve it further. The cause of these reactions, which occur particularly in relationship to the mold Aspergillus fumigatus, is unknown but the author is inclined to the view that they are the result of recurrent infection that induces heightened immunologic reactivity to inhaled allergens. The significance of AF may be simply that this mold has a "predilection for diseased airways" or may be more complex; for example, owing to abnormal ion composition in respiratory secretions, abnormal lectin expression by CF respiratory epithelial cells, or selective filtration by the airways based on particle size.

Correlation of IgE antibody titer to Aspergillus fumigatus with decreased lung function in cystic fibrosis

Obstructive pulmonary disease is a typical feature of cystic fibrosis (CF) and is often associated with bronchial hyperreactivity. Positive skin-test reactions to Aspergillus fumigatus antigens are frequently seen even in nonatopic patients with CF. Full-fledged allergic bronchopulmonary aspergillosis (ABPA) has been estimated to occur in 10% of patients with CF. The relationship between lung function and presence of IgE antibodies to Aspergillus antigens in patients without ABPA is not clear. In 148 outpatients with CF (aged 6-34 years) specific immunoglobulin E (IgE) to Aspergillus fumigatus antigens, basic lung-function parameters, and bronchial response to salbutamol were measured. Multiple regression was performed for age, weight as percentile for actual height (indicating general condition), and Aspergillus RAST. Aspergillus IgE was present in 46% of patients; 19% had RAST class 3 or 4. Independent negative correlations of Aspergillus RAST with FEV1, FEF50%, FEF25%, RV, Chrispin Norman score, and sRaw (P less than 0.05) were found. Bronchodilator sensitivity did not correlate significantly with age and weight percentile. However, Aspergillus RAST did correlate significantly with bronchodilator response measured by sRaw (P less than 0.05). High titers of Aspergillus RAST might serve as a selective criterion for patients to be included in future studies evaluating broncholytic or antiphlogistic therapies.

The pathology of fungal infection and colonization in patients with cystic fibrosis

We used methenamine silver stains to retrospectively evaluate the prevalence of fungi and their associated inflammatory reactions in 63 patients with cystic fibrosis (CF) autopsied between 1982 and 1987. Fungi were detected in 13 patients (21%) who fell into three groups: respiratory tract colonization (five patients); localized infection (five patients); and disseminated infection (three patients). Hyphae consistent with Aspergillus sp were present in five patients; yeast-like cells and/or pseudohyphae consistent with Candida sp occurred in eight patients; and Histoplasma capsulatum produced fibrocaseous lymph node and splenic granulomas in one patient. Acute inflammation typified most fungal lesions, while bronchocentric granulomatosis affected one patient. Compared with patients with no fungi, those with fungi were more frequently treated with indwelling central venous catheters (P less than .05). Autopsy reports on 156 CF patients from 1964 to 1982 disclosed only one with disseminated mycosis (P less than .05). We conclude that stainable fungi can be found in CF patients at autopsy more frequently than previously realized. Fungi usually represent respiratory tract colonization or minimal localized infection, but the prevalence of fatal disseminated infection (4.8%) has also increased. Fungal infection in CF appears to be most closely associated with aggressive therapeutic intervention.

Immune responses to Aspergillus in cystic fibrosis

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

Serum antibodies to Aspergillus fumigatus catalase in patients with cystic fibrosis

Seven to ten percent of patients with cystic fibrosis had serum antibodies to the catalase antigen of Aspergillus fumigatus in three cross-sectional surveys between 1977 and 1984. A total of 208 patients participated at least once, and the cumulated frequency of catalase antibodies in 94 patients included in all three surveys was 16%. The titre range was 1 to 16. The prevalence rate of Aspergillus fumigatus in sputum was 50% for a 2.5-year observation period. Catalase antibodies were strongly associated with the occurrence of Aspergillus fumigatus in sputum (p = 0.003), and the microorganism was more numerous in colonized patients with catalase antibodies than in those without such antibodies (p = 0.004). Patients with Aspergillus fumigatus in sputum and a positive catalase antibody test tended to have an adverse development as regards lung function compared to both carriers without antibodies and non-carriers. The observed differences could not, however, be related to different rates of chronic Pseudomonas aeruginosa infection.

Pathogenetic and serological aspects of pulmonary aspergillosis

Af is an important pathogen of the bronchopulmonary system, and the clinical spectrum encompasses aspergilloma, CNPA, IPA, ABPA, bronchial asthma, and allergic alveolitis. Bronchial carriage may, however, not always be associated with pathological effects. The polymorphism of the aspergillus-related disorders seems mostly to depend upon the different responses of the hosts. This review considers the antigenic composition of Af and specific antibody responses in man in relation to the pathogenesis and diagnosis of the various forms of pulmonary aspergillosis. More than 200 macromolecular components have been listed for Af and more than 30 antigens found to react with human sera. Serum antibodies to Af are common in healthy subjects. Schønheyder and his associates (A-L) have shown that IgG, IgA and IgM antibodies in healthy subjects are directed towards antigens to which also patients with aspergillosis strongly react. With immunofluorescent staining these antigens were found to be associated with hyphal walls, and a MW 470,000 fraction from ruptured mycelium was most reactive in ELISA. The respiratory tract appears to be the major route for exposure since the humoral responses include IgA class antibodies, and sIgA antibodies are found in bronchial secretions. Moreover, IgG antibody levels to the MW 470,000 fraction correlate with occupational exposure and smoking habits. In patients with cystic fibrosis high IgG antibody levels to MW 470,000 and MW 25,000-50,000 antigen fractions were associated with the carriage of Af in the sputum. An individual patient's level of IgA antibodies to the MW 470,000 fraction was inversely related to the Af carrier rate, and this was also true for IgE dependent reactivity to Af antigens. These observations indicate that IgG antibodies to some antigens mirror the extent of antigenic exposure, whereas some IgA and IgE antibodies may play a protective role against bronchial colonization with Af. IgG antibody determinations by ELISA were found to provide a higher diagnostic efficacy in pulmonary aspergillosis than IgA antibody assays. With IgG antibodies there were statistically significant differences between patients and the controls and there was little overlap of ELISA values between the groups. The fractions of MW 250,000 with catalase activity and MW 25,000-50,000 with protease activity, were most suitable for serological diagnosis. A gel immunoelectrophoretic assay proved Af catalase to be a major diagnostic antigen in patients with aspergilloma or with an apical aspergillus lung infiltrate.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunologic aspects of surface infections in the lung

The hallmark of cystic fibrosis is progressive bronchopulmonary damage associated with chronic infection with Pseudomonas aeruginosa, leading to respiratory failure and, ultimately, death. P. aeruginosa is an essentially nonvirulent organism in an immunocompetent host, but it has been shown to colonize the respiratory tract progressively in more than 80% of patients with CF. Patients with CF do not exhibit any evidence of immunologic compromise, and the infection is limited to the mucosal surfaces of the respiratory tract. Thus, P. aeruginosa in bronchopulmonary disease is a unique chronic mucosal infection resulting in a progressive pathologic process. It is therefore conceivable that locally induced alteration in the pulmonary mucosal defense is a major mechanism underlying the development of lung disease in patients with CF. An understanding of immunologic homeostasis in the mucous membranes and in the bronchopulmonary epithelium should provide a better perspective on the factors contributing to the acquisition and chronicity of P. aeruginosa infection in the lower respiratory tract and the development of progressive pulmonary damage unique to CF.

Alternate-day prednisone reduces morbidity and improves pulmonary function in cystic fibrosis

A randomised, double-blind, placebo-controlled study examined the effects of alternate-day prednisone therapy on morbidity and progression of lung disease in cystic fibrosis (CF). At baseline the patients (aged 1-12 years) had mild to moderate lung disease, and the prednisone group did not differ significantly from the placebo group for any values measured. After 4 years, the prednisone-treated group had significant advantages over the placebo group for height, weight, vital capacity, forced expiratory volume in 1 s, peak flow rate, erythrocyte sedimentation rate, and serum IgG. The prednisone-treated group required 9 admissions to hospital for CF-related pulmonary disease compared with 35 for the placebo group. There were no steroid-induced side-effects. To rule out bias in case selection, 69 CF clinic patients comparable in age and clinical status but not included in the study were compared with the placebo group at 4 years; no significant differences between the groups were found.

Bronchial allergy in cystic fibrosis

Thirty-one patients with cystic fibrosis (CF) were thoroughly evaluated for allergy. This included a clinical history, skin tests with twenty-three allergens and bronchial provocation with inhaled allergens and histamine. The bronchial response was measured by whole body plethysmography. Of the patients studied, 40% showed a bronchoconstrictor response to inhaled allergens, despite the fact that none had reported asthma in their clinical history. Strong skin test reactions (3+ and 4+) and weak reactions (2+) were associated with 65% and 4% of positive reactions of the airways respectively. Weak skin reactions with Aspergillus fumigatus, however, were associated with 43% of positive bronchial challenges. In addition to Aspergillus, the mould Alternaria tenuis was found to be an important allergen causing a bronchial response in CF patients. There was no correlation between the thresholds of bronchial sensitivity to allergen and histamine, suggesting that the pathogenetic mechanisms of CF and bronchial asthma are different.

Cystic fibrosis

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Allergic bronchopulmonary aspergillosis in cystic fibrosis

One hundred patients with CF were screened for ABPA. Forty-eight male patients and 52 female patients with age range of 2 to 34 yr (mean 14.2) were studied. Patients were evaluated for skin reactivity and serum precipitating antibodies to Af, predominant sputum organisms, total blood eosinophil levels, total serum IgE, and Af-specific IgE and IgG, as well as abnormalities of pulmonary function and chest x-ray films. Careful evaluation of all patients with CF demonstrated that 10% had features indicative of ABPA, which is another potentially destructive pulmonary disorder. Thus careful evaluation of patients with CF, especially those with asthma, may be rewarding in uncovering a disorder that may slow progression of CF when it is appropriately treated.

Pseudomonas infection, allergy, and cystic fibrosis

The clinical significance of the high prevalence of positive immediate skin tests in cystic fibrosis is unclear. Using analysis of variance, we have tested the hypothesis that patients with allergic cystic fibrosis have worse lung disease than non-allergic patients. Clinical data, skin prick tests, total or specific IgE antibody levels, chest radiographs, and pulmonary function tests were obtained in 104 cystic fibrosis patients. Patients with positive immediate skin reactions to at least one allergen were more likely to be persistently colonised by Pseudomonas aeruginosa than skin test negative patients. The skin test positive patients were also significantly older (mean difference 2.15 years). Analysis of variance showed that pseudomonas infection was the most significant factor contributing to lung damage and the effect of allergy was not significant. Similar longitudinal analysis of pulmonary function over 5 years and study of the hospital admission rate showed that the only statistically significant factor associated with deterioration was colonisation with P. aeruginosa.

Another smoking hazard: raised serum IgE concentration and increased risk of occupational allergy

Individual smoking histories of a general population sample and of two groups of workers exposed to occupational allergens were related to serum IgE concentrations and results of radioallergosorbent and prick tests in the workers. The geometric mean IgE concentration was higher in smokers than in non-smokers. The distribution of serum IgE values in the two groups showed an apparent difference, with a bimodal appearance in the smokers. Evidence of sensitisation against occupational allergens was more common in workers who smoked. The adjuvant effect of smoking on IgE antibody production might be due to damage to airways mucosa and supports the mucosal theory of atopy.

Atopy and cystic fibrosis. A study of CF sibling pairs and their families

We have investigated the prevalence of atopy within families of cystic fibrosis (CF) patients and compared its frequence in CF patients, their parents and their non-CF siblings. By studying families with two CF patients it was also possible to evaluate the factors influencing the development of atopy in one CF patient relative to the other patient within the same family. A significant correlation with age (P less than 0.001) for skin test positivity to common allergens within CF sibling pairs was observed. In 14/18 families studied, only the older CF patient was atopic. The presence of atopy in CF patients was independent of the atopic status of their parents.

Respiratory infections in cystic fibrosis patients caused by virus, chlamydia and mycoplasma--possible synergism with Pseudomonas aeruginosa

116 cystic fibrosis patients were observed, by monthly examinations over an eight-month period, to investigate the importance of non-bacterial respiratory infections (NBI) in exacerbations of the respiratory disease. Sputum was examined for bacteria, and serum investigated for antibody response against virus, mycoplasma and chlamydia and for antibodies against Pseudomonas aeruginosa. During this period each patient had, on an average, 2.9 exacerbations of which 76% were associated with bacteria, most frequently P. aeruginosa (51%), and 20% with NBI, although bacteria were also present in most of these cases. No etiology was established in 18% of the exacerbations. The NBI were caused by respiratory syncytial virus (RSV) (9%), parainfluenza virus (5%), influenza virus (3.6%), adenovirus (2.4%), mycoplasma (0.6%) and chlamydia (0.6%). The incidence of exacerbations was higher in patients with chronic P. aeruginosa infections. RSV infections were more common in patients who developed chronic P. aeruginosa infection during the study period, and RSV infections were frequently associated with a rise of P. aeruginosa antibodies in patients who harboured these bacteria. The important role of NBI as mediators of onset of chronic P. aeruginosa infections in cystic fibrosis patients is suggested.

An automated particle-counting immunoassay (PACIA) for serum IgE

Total IgE was determined in 107 sera using a novel, automated, non-isotopic immunoassay called PACIA (particle-counting immunoassay) based on agglutination of anti-IgE coated latex particles by IgE. The IgE values ranged from 10 to 50,000 iu/ml and were compared with results obtained by a conventional radioimmunoassay (RIA) which used a fast double antibody separation technique--the coefficient of correlation was 0.985 and the regression line y = 0.82 x +130.00. PACIA had several advantages over the RIA technique: using a sampling rate of 50/hr, results were obtained in 35 min compared to 16-20 hr, no labelled IgE was required and the separation step, which relied on measuring the number of non-agglutinated particles by an optical cell counter, was fully automated. The threshold of sensitivity was 10 iu/ml and the maximal coefficient of variation for between assay precision was 12.9%.

125I-Clq-binding and specific antibodies as indicators of pulmonary disease activity in cystic fibrosis

We studied the incidence and levels of circulating immune complexes by the 125I-Clq-binding assay in patients with cystic fibrosis in relation to clinical respiratory status and specific IgG and IgE antibodies to Pseudomonas aeruginosa. Staphylococcus aureus, Aspergillus fumigatus, and Candida albicans. Overall prevalence of CIC was 43%, but 86% of serially studied patients had evidence of CIC at some time. Patients with acute respiratory exacerbations and deteriorating pulmonary function had a higher incidence of CIC (76%) as compared to stable patients (36%, P less than 0.01), as well as significantly higher levels of CIC. Acute exacerbations were also associated with significant increases in IgG antibody to Pseudomonas (P less than 0.005) but not in other antibodies. CIC did not correlate with Pseudomonas-specific IgG nor with any other specific antibody studied. A variety of age-related differences in specific antibody levels were seen. The episodic appearance of CIC is common in CF and is usually associated with exacerbation of lung disease.

Positive immediate skin tests in cystic fibrosis: a possible role for Pseudomonas infection

A review was made of the medical records of 49 patients from whose sputum mucoid Pseudomonas aeruginosa had been isolated over a 20-month period. This showed that 31 of 42 had positive immediate skin prick tests to common antigens. 21 had positive reactions to Aspergillus fumigatus antigens and 23 had precipitins to A. fumigatus antigen. 36 patients had had frequent courses of antibiotics and airway obstruction was present in 47. These results have prompted the hypothesis that the positive skin test reactions in patients with cystic fibrosis may in part be explained by the abundance of fungal and bacterial antigens that occur in the respiratory tract of these patients. The former antigens sensitize the immunoglobulin E producing cells whilst the latter exert an adjuvant action and facilitate this.

Atopy and bronchial reactivity in older patients with cystic fibrosis

We studied 25 adolescent and adult patients with cystic fibrosis (CF) and 25 control subjects to determine if the prevalence of atopy and bronchial hyperreactivity was increased in this disease. Results showed that atopic symptoms, as defined by history, were more frequently present in the CF patients. Prick testing of the skin produced positive reactions in 88% of the CF group and 36% of the control subjects (p less than 0.001), and the mean number of reactions per subject was significantly higher in the former group (p less than 0.001); reactions to fungal antigens were strikingly positive in the CF group. The CF patients had a significantly higher mean serum IgG4 (p less than 0.001), IgE (p less than 0.01), and higher mean eosinophil count (p less than 0.05). Clear-cut bronchial hyperreactivity was demonstrated in the CF group compared with control subjects. Bronchial provocation with 400 micrograms of histamine led to a greater than 15% fall in the preinhalation FEV1 in 35% of the CF subjects compared with 4% of the control group, with a mean percentage fall of 15% and 3% respectively (p less than 0.001). In the CF group a greater than 15% rise in PEFR occurred in 32% after inhalation of the parasympatholytic, ipratropium bromide (54 micrograms), and in 27% after inhalation of the sympathomimetic, fenoterol (400 micrograms). No correlation was found between bronchial reactivity and atopic status, HLA phenotype pattern, or disease severity. The cause of the increased prevalence of atopy and bronchial reactivity in CF patients remains unknown. However, it is clear that a trial of bronchodilator therapy is warranted in adolescents and young adults with CF.

Reversible airway obstruction in cystic fibrosis

Fourteen (29%) of 48 children with cystic fibrosis had a greater than 15% improvement in forced expiratory volume in one second, or in forced vital capacity after inhalation of salbutamol. All these children were atopic (one or more positive prick tests) and had a significantly higher mean serum IgE than either non-atopic subjects or those atopic subjects without airways reversibility (p less than 0.02). Half of those with airways reversibility had or subsequently developed the clinical picture of allergic bronchopulmonary aspergillosis. Of the whole group 81% were atopic, of whom 77% had a positive reaction to A fumigatus, 64% to housedust, and 56% each to grass pollen and cat hair. Children who were not atopic had significantly better spirometry (p greater than 0.05) than those who were. Children with skin hypersensitivity to A fumigatus had identical spirometry to those who were atopic without reactivity to A fumigatus. Serum precipitins to A fumigatus were present in 48%. Serum precipitins to pancreatin were present in 71%, but the presence of these precipitins did not correlate with atopy, airways reversibility, or serum IgE.

Hypogammaglobulinemia in patients with cystic fibrosis

To investigate some aspects of immune function in cystic fibrosis, we measured serum immunoglobulins in 419 patients. Twenty-two per cent of the 154 patients less than 10 years old had hypogammaglobulinemia-G, whereas the older patients had normal or elevated serum immunoglobulins. A single mechanism accounting for the extraordinary prevalence of hypogammaglobulinemia in young patients with cystic fibrosis was not defined in studies of T and B-lymphocyte function in vitro or in studies of IgG metabolism in vivo. Analysis of objective clinical data, including arterial blood gases, chest roentgenograms, and bacteriologic cultures, indicated that the patients with hypogammaglobulinemia had significantly less severe lung disease than did age-matched patients with cystic fibrosis and normal or elevated IgG levels. We conclude that progression of lung disease may be due in part to a hyper-immune response.

Response to bronchial provocation and exercise in children with cystic fibrosis

Ten of fifteen cystic fibrosis children with positive skin prick tests to common antigens gave an immediate bronchial reaction to the antigen inhaled, five of them also gave a late reaction; however only one gave a history of asthma. The antigen most commonly eliciting a positive skin reaction in cystic fibrosis patients is Aspergillus fumigatus. In six children tested to this antigen the bronchial response varied, two were negative, one gave an immediate reaction and three gave a dual (immediate and late) reaction. None of the children showed the characteristic pattern of response to exercise seen in asthmatic patients, an initial rise in Peak Expiratory Flow Rate followed by a fall of greater than 14% below the resting level. Two patients showed an abnormal rise in Peak Expiratory Flow Rate during exercise, a pattern described previously in cystic fibrosis. The results suggest that bronchial allergy, immediate or late does completely explain susceptibility to asthma, and that other factors including perhaps the type of bronchial reactivity shown by bronchoconstriction after exercise may be required. However the majority of the children tested had bronchial allergy and anti-allergy therapy such as inhaled sodium cromoglycate may have a place in the management of selected patients with cystic fibrosis.

Immunological studies in cystic fibrosis

Evidence is presented to support the concept that much of the allergy in cystic fibrosis (CF) is IgE mediated. Total IgE levels were higher in allergic than in nonallergic CF patients. Levels were also higher in those patients who had had the greatest number of chest infections in the preceding 12 months. IgE antibody levels to Dermatophagoides pteronyssinus, Timothy grass pollen, and Aspergillus fumigatus were higher in those with positive results from skin tests to these allergens. The serum IgG, IgM, and IgA levels of allergic and nonallergic CF patients did not differ but the overall mean values for IgG and IgM were higher than those reported for healthy British children. The highest levels tended to be present in patients with the greatest number of recent major chest infections and the difference was significant for IgG. 16 patients had IgA levels 72SD below the reported means for age-matched controls and 11 of these were nonallergic. IgA levels were also higher in patients who had recently experienced major chest infections. 45 of the patients were tissue types for HLA A and B antigens but no significant clinical associations with single antigens were observed. The antigen phenotype A1 + B8 was more common in datients with multiple allergic symptoms than in those with a single allergy or merely a positive result from a skin test Nonsignificant increases of W19 in patients with frequent infections and of A2 in patients presenting with meconium ileus were also noted. The data presented do not permit a choice to be made between the alternative concepts of allergy as a primary abnormality in CF, and allergy arising secondary to infection.

Precipitating antibody to antigens of Pseudomonas aeruginosa in chronic obstructive lung disease

Two antigens designated Pseudomonas aeruginosa cytoplasmic antigen (P(1-5)) and P. aeruginosa cell wal antigen (PCW) were prepared by ultrasonic disintegration and hot phenol extraction of a smooth polyagglutinable strain of P. aeruginosa isolated from the respiratory tract. It was shown that P(1-5) and PCW are immunologically distinct, that P(1-5) is heat-labile while PCW contains a heat-stable component which stains positively for polysaccharide, is positive for endotoxin and cross-reacts with a cell wall antigen of Haemophilus influenzae prepared by hot phenol extraction. Both antigens were able to activate the alternate pathway for complement. A statistically significant number of patients with cystic fibrosis and bronchiectasis have precipitating antibody to that fraction of cytoplasmic antigen specific for P. aeruginosa (P(1-2)) and PCW compared to controls, whereas patients with asthma and chronic bronchitis do not. The use of both antigens increases the number of patients with antibody to P. aeruginosa. Radioactive immunodiffusion studies indicate that 80.8% of controls have precipitating antibody to PCW antigen and that antibody to it is IgG, IgA and IgM. These studies indicate that consideration should be given to PCW as well as P(1-5) in any consideration of the pathogenesis of P. aeruginosa in these conditions.

The variability of skin test hypersensitivity reactions in cystic fibrosis and asthma

Cystic fibrosis (CF) children had a greater variability of skin prick test response compared with asthmatic children, when the tests were performed on two occasions. This suggests that there is a different cause for the allergy in the two groups, perhaps because the asthmatics have a transient period of susceptibility to sensitization in infancy and the CF children a persistent vulnerability. Amongst the asthmatic children, clinical improvement was associated with loss of some skin prick test reactions, and clinical deterioration with an increase in the number of positive reactions. Thus continuing allergic reactions may maintain a mucosal defect, resulting in a persistence of susceptibility to allergen sensitization, and control of the reactions may re-establish normal mucosal defence mechanisms.

Association of cystic fibrosis with allergy

Immediate skin hypersensitivity to various inhalant allergens was present in 59% of 123 children with cystic fibrosis (CF), a much higher percentage than in the general population. This is consistent with the idea that atopy arises as a result of impaired handling of antigen at mucosal surfaces. The allergic CF children had more chest infections, a worse chest x-ray appearance, and lower peak expiratory flow rates. Allergic diseases were also frequent in the CF obligate heterozygotes (32% of mothers and 26% of fathers). It is suggested that the heterozygotes may also have a mucosal abnormality resulting in defective antigen handling.

Cystic fibrosis heterozygosity in the pathogenesis of allergy

47% of cystic fibrosis (C.F.) heterozygotes had positive prick skin tests of 1 or more of 9 antigens and 53% had histories of allergic disease, both occurring significantly more often than in a control group. Since 1 in 20 of the population are C.F. carriers, this would contribute to allergy in the community.

Sources and incidence of airborne Aspergillus fumigatus (Fres)

Specific surveys of the air for Aspergillus fumigatus were carried out in rural and urban situations over a 2-year period. Overall, low concentrations of spores were recorded with a higher incidence during the "winter" months. Counts in the open air and in a hospital ward showed similar fluctuations, the indoor counts being consistently lower. Plant debris in the form of compost heaps and stacks of hay and straw baled with a high moisture content in which self-heating occurs, produces large numbers of spores which may be liberated into the air causing high but localized counts if disturbed. The widespread distribution of decaying leaves following leaf fall represents a potential source of smaller concentrations of spores but over a much larger area. This availability of decaying plant debris with high water content fulfils the growth requirements of Aspergillus fumigatus and is the probable explanation of its winter seasonality.

Cell-mediated immunity in patients with cystic fibrosis

Leucocytes from 26 patients with cystic fibrosis (CF) and 18 healthy controls were investigated by migration inhibition induced by a variety of antigens. In patients with CF cell-mediated immunity was found to human lung and pancreatic tissue extracts as well as to Aspergillus fumigatus, Pseudomonas aeruginosa, and food antigens but not to brain, heart, or kidney. Those patients with the severest form of the disease had the greatest impairment of cell-mediated immunity, but this impairment could be reversed by steroid treatment. Cell-mediated cytotoxicity may also be concerned in the pathogenesis of CF.