Maria-José Rodrigo

Identification and partial characterization of the soybean-dust allergens involved in the Barcelona asthma epidemic

Asthma epidemics in Barcelona, Spain, have been attributed to dust generated by the unloading of soybeans in the harbor. Sera of four different groups of 10 subjects in each group were studied: (1) patients attending an emergency room in Barcelona for an asthma attack on epidemic days, group A, (2) patients attending an emergency room for an attack on nonepidemic days, group B, (3) patients with asthma from other cities, group C, and (4) patients without asthma from Barcelona matched by age and sex with group A, group D. All subjects in group A had IgE to allergens in extracts of various soybean samples. In contrast, only one of the 10 subjects in each of groups B and C and none of those subjects in group D had IgE to uncleaned bean and hull extracts. Radioimmunoassay demonstrated that in sera from patients with asthma during an asthma outbreak reacted primarily to soybean hull and dust extracts. Sodium dodecyl sulfate-polyacrylamide and gel electrophoresis thin-layer isoelectrofocusing demonstrated protein bands of 97.4 to less than 14.4 kd and isoelectric point between 6 and 3.5. By Western blot and thin layer isoelectrofocusing/blotted radioimmunoisoelectrofocusing, IgE of patients with asthma during an asthma outbreak reacted weakly to two protein bands of molecular weight ranging from 42 to 21 kd, strongly to glycoprotein bands with molecular weight less than 14.4 kd, and isoelectric point less than 6, which appeared to be the major allergens.

CASE-CONTROL STUDY OF SERUM IMMUNOGLOBULIN-E ANTIBODIES REACTIVE WITH SOYBEAN IN EPIDEMIC ASTHMA

Since 1981, twenty-six asthma outbreaks have been identified in Barcelona, all coinciding with the unloading of soybean in the harbour. Serum from patients with epidemic asthma and individually matched controls with non-epidemic asthma was assayed for immunoglobulin-E (IgE) antibodies against soybean antigens by means of a radioallergosorbent test. In 64 of 86 cases (74.4%) there was a reaction with commercial soybean antigen extracts, compared with only 4 of the 86 controls (4.6%) (odds ratio = 61; lower 95% confidence limit = 8.1). The statistical significance was greater for reactions with extracts of soybean dust taken from Barcelona harbour (odds ratio, unquantifiably high; lower 95% confidence limit = 11.7). No other serological covariate (total serum IgE levels or specific IgE levels against the commonest airborne allergens or legumes) confounded the association between serum anti-soybean IgE antibodies and epidemic asthma. These results support a causal relation between the release of dust during unloading of soybean at the harbour and the occurrence of asthma outbreaks, suggesting an underlying allergic mechanism.

Detection of specific antibodies to pigeon serum and bloom antigens by enzyme linked immunosorbent assay in pigeon breeder's disease

BACKGROUND Pigeon breeders disease is an extrinsic allergic alveolitis in the lungs of sensitised people, caused by hypersensitivity reactions to inhaled pigeon antigens. Antigens from different sources of the animal are used for diagnostic purposes, with serum being the most widely used. Bloom is rarely used; very little is known of its antigenicity and diagnostic performance, particularly when used with the enzyme linked immunosorbent assay (ELISA) method, which is the most popular test as it permits measurement of the antibody response. METHODS To (a) standardise an ELISA for the measurement of specific IgG against pigeon serum and pigeon bloom extract; (b) to establish reference values for specific IgG in 73 non-exposed controls, (c) to show the presence of specific IgG against pigeon serum and bloom in serum samples of 17 patients with bird fanciers lung and 11 asymptomatic fanciers, and (d) to study the similarity of the two antigen sources by cross reactivity experiments. RESULTS Reference values of specific IgG were defined with the 97.5 percentile (367.9 U/ml for pigeon serum and 953.7 U/ml for pigeon bloom extract). Of symptomatic patients 100% had values higher than the cut off for both antigens. In asymptomatic fanciers values were higher than the cut off for pigeon serum in 45% and bloom extract in 54%. Cross reactivity experiments showed that the two antigens differed in antigenic content although some components may be common to both. CONCLUSION The ELISA methods used proved to be useful tools for evaluating specific IgG antibody responses against both antigens. The diagnostic performance of both ELISA methods performed with these antigen sources was similar, showing very high sensitivity but moderate specificity. Although some antigenic similarity was found between pigeon serum and bloom extract, cross reactivity studies showed that various antigens seemed to be specific to the bloom extract. However, the antigens responsible for pigeon breeders disease seem to be present in both antigenic sources.

An Amplified ELISA Inhibition Method for the Measurement of Airborne Soybean Allergens

Background: Measurement of the soybean aeroallergen in Barcelona and other cities where soybean is unloaded is of increasing importance in controlling population exposure and evaluating the influence of such exposure on the persistence of asthma symtpoms. Objective: The aims of the study were: (1) to standardize an amplified ELISA inhibition method for the quantification of soybean aeroallergen and (2) to compare this method to a previously described RAST inhibition method. Methods and Results: An amplified competitive ELISA inhibition method with a biotin-streptavidin system was carried out using a pool of sera from soybean-sensitized patients. The results were expressed as U/ml using a low-molecular-mass soybean allergen as reference standard. Reproducibility was calculated by statistically comparing the slope of the regression lines of the standard curve of 4 consecutive assays and by determining the coefficient of variation (CV) of the percent inhibition data for each point of several independent standard curves, each from the same assay (intra-assay) and also from a separate assay (inter-assay). No significant differences in the slopes were obtained by analysis of covariance (ANCOVA) F = 1.04. The CV between assays varied between 4 and 22% (for the assay range used in the reference standard) and was greater than the CV within assays (5–10%). Only values with a CV(%) smaller than 20% were considered acceptable. 78.5% of the samples satisfied this criterion. The RAST inhibition and ELISA inhibition methods were compared by difference plots from the values of 338 air filter eluates. The intraclass correlation coefficient was 0.456 (p < 0.001). After the results of both methods were classified as lower and higher than 165 U/m3, the kappa index was 0.46 (p < 0.001). Conclusions: The data obtained in the present study are comparable to those reported from other similar immunoassays. Moreover, despite the difficulty in comparing air-sampling values from different laboratories, the kappa index may be taken to represent fairly good agreement beyond chance between both methods. All these data demonstrate that the present immunoassay is useful for measuring airborne soybean aeroallergens and can also be applied to evaluate the relationship between exposure and the development of asthma symptoms.

Mollusk shell hypersensitivity pneumonitis.

Excerpt The shells of certain mollusks, as well as oyster shells, sea-snail shells, and others, provide the raw material used to manufacture nacre products. Weiss and Baur (1) suggested in 1987 a p...

Epidemic Asthma in Barcelona: An Evaluation of New Strategies for the Control of Soybean Dust Emission

Background: Asthma attacks and mortality due to inhalation of soybean antigens in Barcelona have been well documented. Strict protective measures in the unloading process were established in 1998 to avoid the release of soybean dust into the atmosphere. The present study was undertaken to assess the effectiveness of these latest environmental measures, and, if effective, to recommend their implementation in the many harbours where soybean is unloaded. Methods: Levels of soybean aeroallergen were analysed daily during a period of 5 years and 2 months in a total of 1,854 samples, 125 from the pre-intervention period and 1,729 from the postintervention period. Additionally, the number of asthma admissions to the emergency rooms of the city’s three largest hospitals was recorded. Asthma patients attended at home by the public home emergency service and judicial autopsies registering asthma deaths were also investigated. Results: The mean concentration of soybean aeroallergen was 159 U/m3 in the pre-intervention period and 39 U/m3 in the postintervention period (p < 0.0001). Significant differences in postintervention aeroallergen concentrations were found between days of soybean unloading (42 U/m3) and days of no unloading (33 U/m3), with p < 0.0001. No significant relationship was found between concentrations of environmental soybean aeroallergens and the number of emergency room admissions for asthma. Conclusions: Implementation of stricter protective measures in silos for the soybean unloading process has reduced the concentration of soybean dust in the atmosphere and evidences the effectiveness of the measures adopted.

Clinical and functional characteristics of patients two years after being affected by the soybean asthma epidemic in Barcelona.

BACKGROUND--Patients affected during the asthma outbreaks caused by soybean dust inhalation in Barcelona presented with sudden onset of severe asthma followed by the rapid relief of symptoms after treatment. Two years after the epidemics ended, a case-control study was conducted in which the clinical, functional, and immunological characteristics of these asthma patients (a randomised sample of asthmatic patients admitted as emergency cases on epidemic days, n = 213) were compared with those of a control group (a random sample of asthmatic patients admitted as emergency cases for attacks of asthma on non-epidemic days, n = 170). METHODS--The study included the administration of the ATS-DLD78 standardised respiratory questionnaire, the measurement of atopy, and performance of spirometric tests and a methacholine inhalation test. RESULTS--Patients with epidemic asthma reported fewer symptoms of asthma, had attended emergency departments less frequently during the previous year for acute attacks of asthma, were taking fewer inhaled corticosteroids at the time of the study, and attended medical follow up less frequently than did the patients with non-epidemic asthma. However, the cases and controls showed no differences in ventilatory capacity or reactivity to the methacholine bronchoprovocation test. CONCLUSIONS--Two years after the end of the soybean epidemics, people affected by epidemic asthma had a favourable prognosis. This finding contrasts with a higher risk of life threatening asthma and death during the epidemics. This paradox could be the result of a complex interaction between host and conditions of exposure.

Association study of proposed candidate genes/regions in a population of Spanish asthmatics

A number of genes/regions have recently been reported to be linked to asthma or its related phenotypes (i.e. atopy and bronchial hyperresponsiveness), by genetic linkage and allele-sharing methods. We have performed a case–control study comparing the allelic distribution of nine microsatellite markers and two genetic variants in a group of patients attended at emergency room departments because of an acute attack of asthma with respect to an external healthy population of controls. A total of 146 asthmatic subjects and 50 population controls from Barcelona, Spain, were genotyped for nine microsatellite markers from some asthma/atopy candidate genes/regions: the β-subunit of the high-affinity IgE receptor (FcεRI-β) located on chromosome 11; the 5q31–32 candidate region; the T-cell receptor genes, TCR-α on chromosome 14 and TCR-β on chromosome 7. Two genetic variants of the β-subunit of the high-affinity IgE receptor (FcεRI-β) gene were also analyzed. None of the asthmatic or control individuals carried the Ile181Leu variant. There were no significant differences between asthmatic and control subjects neither for the polymorphic markers nor for the other variant of the β-subunit of the high-affinity IgE receptor (FcεRI-β) gene. No association could be observed in this sample of Spanish asthmatics with the genes/regions studied.

Localised alveolar-septal amyloidosis with hypersensitivity pneumonitis.

Localised alveolar-septal amyloidosis has been thought irreversible. A woman exposed to the dust of sea-snail shells during the manufacture of nacre buttons had clinical and immunological features typical of hypersensitivity pneumonitis; however, transbronchial lung biopsy showed alveolar-septal amyloidosis. There was no evidence of other diseases known to be associated with amyloidosis, nor were amyloid deposits found in other organs. After a year without exposure to the antigen there was no trace of either pneumonitis or amyloidosis.