Typical levels of airborne fungal spores in houses without obvious moisture problems during a rainy season in Florida, USA

OBJECTIVE

The aim of this study was to determine types and levels of airborne fungal spores in air-conditioned homes built after 1980 without obvious moisture problems during the 2004 summer (rainy season) in central Florida, USA.

METHODS

Eighteen single-family homes were selected based on protocol questionnaire and cursory inspection, which revealed no obvious moisture or visible fungal growth. Non-cultured spores were collected with Air-O-Cell cassettes. Three indoor air samples and 2 outdoor air samples were collected from each home. One indoor and 2 outdoor samples were not interpretable. Fifty-three indoor and 34 outdoor air samples were analyzed by optical microscopy.

RESULTS

Several spore types were detected in the indoor samples, at levels generally lower than those detected in the outdoor samples. Spores from the Penicillium/Aspergillus group were the most prevalent types indoors, exceeding the absolute levels and relative percentages of these spores outdoors. Ascospores and basidiospores were the most prevalent spore types outdoors. The percentages of other spore types (Cladosporium and Curvularia) were similar in the indoor and outdoor samples. Moisture-indicator fungi (Chaetomium, Stachybotrys, and Ulocladium species) were nearly absent in both indoor and outdoor samples.

CONCLUSION

Airborne fungal spores are present in average central Florida homes without obvious moisture problems during the summer, at levels that are lower than those found outdoors. Spores from the Penicillium/Aspergillus group are prevalent in these homes, and moisture-indicator fungi (Chaetomium, Stachybotrys, and Ulocladium species) are nearly absent. Despite climatic differences, airborne fungal spore types and levels in central Florida houses are similar to those found in other geographical locations.

Allergenicity of varieties of soybean

BACKGROUND

Soybean hulls (SHs) cause respiratory allergies. This study investigates the allergenicity of soybean varieties (SVs) by in vivo and in vitro tests.

METHODS

Ten SVs were studied: (a) five with a proved clinical relevance (SVs 1, 2, 3, 4, 5), the last four with a 'dull' phenotype; (b) five of undetermined relevance, three of them (SVs 6, 7, 8) with a 'shiny' phenotype, and two (SVs 9 and 10) with a 'dull' phenotype. Extracts from all 10 SVs were used to skin prick test (SPT) 21 subjects sensitized to SHs. Positive and negative sera pools prepared from sera of subjects sensitized or not to SHs, respectively, were utilized to perform in vitro experiments (specific IgE and IgG4 determinations, SDS-PAGE/IgE-Western blot, and IgE-inhibition).

RESULTS

In this study, it was found that 52.4, 52.4, 57.1, 71.4, 80.9, 42.9, 57.1, 71.4, 52.4, and 38.1% subjects had a positive SPT with SVs 1-10, respectively (P NS). Specific IgE values to SVs 1-10 obtained with the positive pool are 28.3, 26.4, 29.9, 28.3, 26.8, 4.8, 13.4, 6.7, 24.7, and 17.5% total counts bound, respectively; and specific IgG4 values 0.851, 0.818, 0.721, 1.609, 0.789, 0.617, 0.662, 0.0, 1.127, and 0.934 OD units, respectively; the microgram of protein required to produce 50% inhibition are 2.5, 3.7, 4.5, 2.4, 5, 39.8, 25.2, 25.1, 4.5, and 8.9, respectively. A 7-kDa band is present in all SVs except in those with a 'shiny' phenotype.

CONCLUSIONS

The SVs with a 'shiny' phenotype contain less allergens than the other SVs studied, as determined by in vitro tests. However, SPT results with the SVs do not differ. Genetic screens should be devised to select plants with reduced, preferably absent, allergenicity, but with a high nutritional value, and this allergenicity should be studied utilizing in vivo and in vitro tests.

Disodium octaborate tetrahydrate (DOT) application and vacuum cleaning, a combined strategy to control house dust mites

BACKGROUND

The effectiveness of acaricides in homes is controversial.

OBJECTIVE

To determine whether disodium octaborate tetrahydrate (DOT) combined with vacuuming lowers dust mite numbers and their allergens in carpets and sofas.

METHODS

A 6-month study was carried out with 93 homes, which were randomized into three groups: (i). active, received DOT; (ii). placebo, received water; and (iii). control, received no application. Active and placebo homes were vacuumed weekly. Dust was collected from carpets and sofas at the start of the study and every 2 months thereafter and quantified for live, total mites, and mite allergen levels.

RESULTS

At 2 months, live mite numbers in active carpets were 3 +/- 1, in placebo carpets 129 +/- 48, and in control carpets 177 +/- 39 mites/g. The corresponding numbers in sofas were 3 +/- 2, 81 +/- 31, and 134 +/- 45 mites/g, respectively (P < 0.001 active vs placebo and vs. control). Live mites in carpets and sofas remained lower in the active group at 6 months (P < 0.001). Total mites in active carpets decreased from 555 +/- 69 at baseline to 223 +/- 32 mites/g at 6 months (P < 0.001) and mite allergen levels from 1.36 +/- 0.13 to 0.85 +/- 0.16 microg/g (P < 0.001). Total mites in active sofas remained unchanged, but mite allergen levels decreased from 1.48 +/- 0.25 at baseline to 0.7 +/- 0.15 microg/g at month 6 (P < 0.05).

CONCLUSION

DOT kills mites in carpets and sofas, and, combined with vacuuming, effectively reduces total mites in carpets and mite allergen levels in carpets and sofas.

Identification of the soybean hull allergens involved in sensitization to soybean dust in a rural population from Argentina and N-terminal sequence of a major 50 KD allergen

BACKGROUND

Sensitization to soybean hull (SH) allergens occurs in subjects from Argentina, a soybean producer country. However, the causative allergens have not been identified. The purposes of this study are to: (i) identify the SH allergens using sera of 29 subjects with asthma and/or allergic rhinitis from Argentina exposed to soybean dust who have a positive (weal with SH/weal with histamine > or = 0.5) skin prick test to SH; and (ii) determine the N-terminal amino acid sequence of a major 50 K SH allergen that sensitizes this population.

METHODS

All sera were assayed for specific IgE (RIA), IgG4 (ELISA), and IgE and IgG4-Western blots. A sera pool from 10 healthy subjects was a negative control. N-terminal amino acid sequencing was performed by the Edman degradation method.

RESULTS

Positive specific IgE only was found in 12/29 (41.4%), IgG4 in 3/29 (10.3%), and both IgE and IgG4 in 14/29 (48.3%) sera. IgE-Western blot demonstrates: (i) an allergen, MW 50 K (51.7% binding); (ii) one or two distinct allergens, MW < 20.2 K (72.4% binding), depending on the sera; and (iii) 1-5 additional IgE binding proteins, MW > 20.2 to < 46.9 K (41.4% binding), depending on the sera. IgG4-Western blot demonstrates: (i) a band, MW 70K (31% binding); (ii) a band, MW 50 K (17.2% binding); (iii) one or two additional bands, MW < 20.2 K (51.7% binding), depending on the sera; and (iv) a band, MW > 20.2 to < 28.5 K (20.7% binding). The 50 K allergen N-terminal amino acid sequence of the first 17 amino acids indicates a significant homology with chlorophyll A-B binding protein precursors from tomato, spinach, and petunia.

CONCLUSIONS

Specific IgE and IgG4 to SH are common in sera from allergic individuals living in rural areas in Argentina. SH contain an IgE binding protein, MW about 50 K, not previously described. Sensitization to this allergen is common in subjects who are repeatedly exposed to soybean dust inhalation.

House dust mite, cat, and cockroach allergen concentrations in daycare centers in Tampa, Florida

BACKGROUND

Allergen exposure in early childhood is a risk factor for sensitization and the development of asthma. Studies performed in Europe, New Zealand, and Singapore indicated the presence of indoor allergens in childcare centers and schools. However, the importance of indoor allergens in daycare centers in humid and warm regions of the world is not known.

OBJECTIVE

To measure total mite counts, Der p 1, Der f 1, Fel d 1, and Per a 1 allergens in dust samples and mite allergen airborne concentrations in daycare centers in Tampa, Florida, United States.

METHODS

Twenty daycare centers were surveyed for mite, cat, and cockroach allergens in Tampa, FL. One dust and two air samples (one during the day and one during the night) were collected in each center. Dust samples were extracted and analyzed for mite (Der p 1 and Der f 1), cat (Fel d 1), and cockroach (Per a 1) allergens. Mite airborne allergen concentrations were analyzed by RAST inhibition and expressed in standardized mite allergen units per m3 of air (AU/m3).

RESULTS

Mites were identified in 15 samples, and concentrations ranged from 10 to 1,200 mites/g (298 +/- 355.2). The most prevalent mite species was Dermatophagoides pteronyssinus ( Der p 1). Der p 1 and/or Der f 1 were detected in 10 daycare centers. Der p 1 was detected in eight centers and ranged from I to 21.8 microg/g of dust (5.4 +/- 6.9); Der f 1 was detected in 3 centers and ranged from 0.2 to 2.1 microg/g of dust (1.3 +/- 0.9). Per a 1 and Fel d 1 were detected in all centers in small quantities; Per a 1 ranged from 8 to 1,806 ng/g (263.1 +/- 449.7) and Fel d 1 from 0.2 to 120 U/g of dust (16.6 +/- 31.7), respectively. Airborne mite allergen was detected in 18 centers and ranged from 0.01 to 2.7 AU/m3 during the day (0.2 +/- 0.6) and from 0.01 to 0.12 AU/m3 during the night (0.06 +/- 0.03), P = 0.001.

CONCLUSIONS

Mite, cat, and cockroach allergens are present in daycare centers in Tampa, FL. Mite allergen concentrations exceeded levels that have been associated with sensitization and symptoms in allergic subjects in 40% of these centers.

[Association between soybean dust exposure, allergic sensitivity and profile of respiratory symptoms]

The purpose of this study was to correlate soybean dust (SD) exposure, skin reactivity to soybean hull (SH) allergens, and symptoms of asthma and/or allergic rhinitis. A group of 365 subjects with asthma and/or allergic rhinitis and a control group of 50 individuals without respiratory symptoms were studied. The level of exposure to SD is defined as follows: 1) direct (DE); 2) indirect (ID), and 3) urban (UE). All subjects completed standard questionnaires. Skin tests with a SH extract and with common allergens were performed by the prick technique (SPT). Fifty-six (15.3%) patients and no subjects from control group had positive SPT (histamine index > or = 0.5) with a SH allergen extract. The percentages of positive SPT to SH extract were 38.7%, 20.3% and 8.4% in subjects with DE, IE and UE, respectively (p < 0.001). Monosensitization to SH was absent in all subjects. The percent of subjects with positive SPTs to mites (p < 0.01), pollen (p < 0.01) and molds (p < 0.05) were higher in subjects with a positive SPT to SH versus those with a negative SPT to SH. Sixty-six percent of subjects with DE and 13.6% of subjects with IE or UE reported respiratory symptoms after SD inhalation (Odds Ratio: 12.67 [2.4-74.9], p < 0.001). Compared to subjects exclusively sensitized to mites, patients sensitized to SH presented significantly different clinical characteristics. Soybean production has been increasing in Argentina during the last 20 years, determining an increase in the population exposed to chronic SD inhalation. This fact determines a high risk of sensitization and triggering of respiratory symptoms in atopic subjects. This study demonstrates that there is: 1) a high prevalence of skin reactivity to SH in subjects with asthma and/or allergic rhinitis from Argentina and that this prevalence is associated with the level of exposure to SD, and 2) an association between sensitivity to SH and severity of asthma. Measures to avoid release and inhalation of SD in rural areas from Argentina are needed.

Sensitization to soybean hull allergens in subjects exposed to different levels of soybean dust inhalation in Argentina

BACKGROUND

Soybean hulls (SHs) have been identified as the source of aeroallergens responsible for soybean asthma outbreaks. However, the prevalence of sensitization to SH allergens in subjects from Argentina, a country where soybeans are produced, is unknown.

OBJECTIVE

The purpose of this study was to determine the prevalence of sensitization to SH by in vivo and in vitro tests in subjects with asthma or allergic rhinitis and in control subjects from Argentina who have been exposed to different levels of soybean dust inhalation (SDI).

METHODS

Exposure to SDI is defined as follows: (1) direct = occupational, (2) indirect = proximity to soybean fields or grain elevators, and (3) urban = urbanized areas without a known source of SDI. Two groups were studied. Group 1 consisted of 365 subjects with asthma or allergic rhinitis and group 2 (control group) of 50 healthy individuals. Subjects from both groups were classified according to their exposure to SDI. All subjects completed standard questionnaires. Prick skin tests (STs) with an SH extract and with common allergens were performed on all subjects. Specific IgE and IgG4 to SH were measured in sera of 51 of 56 subjects from group 1 who had a positive ST to SH and in all sera from group 2.

RESULTS

Fifty-six (15.3%) subjects from group 1 and no subjects from group 2 had a positive ST to SH (wheal SH/wheal histamine >/=0.5). In group 1, positive STs to SH were 38.7%, 20.3%, and 8.2% in subjects with direct, indirect, and urban exposures, respectively (P <.001). Monosensitization to SH is absent in all subjects from group 1. The percent of subjects with positive STs to mites, pollen, and molds was highest in those with a positive ST to SH versus those with a negative ST to SH (P <.01). Asthmatic patients with a positive ST to SH, compared with those exclusively sensitized to mites, had a higher frequency of daily or weekly symptoms (59.4% vs 25.7%, respectively, P <.001) and a higher percent of glucocorticoid dependence (52.8% vs 34%, respectively, P <.01). Percent positive IgE in group 1 and group 2 were 39.2% and 10% (P <.001) and percents positive IgG4 are 27.4% and 12%, respectively (not significant). In subjects from group 1 and group 2 with direct exposure percents positive IgE are 58.3% and 13.3% (P < .001) and percents positive IgG4 were 75% and 20%, respectively (P < .02). IgG4 in group 1 was significantly higher in subjects with direct exposure compared with subjects with indirect or urban exposure.

CONCLUSION

This study demonstrated that there was (1) a high prevalence of sensitivity to SH in subjects with asthma or allergic rhinitis from Argentina and (2) an association between sensitivity to SH and severity of asthma and level of exposure to SDI.

Identification of the soybean hull allergens responsible for the Barcelona asthma outbreaks

BACKGROUND

Soybean hulls were identified as the etiologic agent responsible for the asthma outbreaks that occurred in Barcelona and Cartagena, Spain.

OBJECTIVE

To identify the main soybean hull allergens using the sera of 18 asthmatic epidemic patients from Barcelona and to compare the results to those previously reported.

METHODS

Specific IgE to a soybean hull allergen extract was determined by radioimmunoassay and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in a 10-20% Tris-tricine gradient gel followed by Western blot.

RESULTS

Specific IgE, which was detected in 15 of the 18 (83.3%) sera, indicated two nonoverlapping band patterns on the SDS-PAGE/Western blot: (1) pattern 1, present in 11 sera, consisted of three bands with estimated molecular weights (MWs) of 8, 7.5 and 7 kD, which are the MWs described for the allergens Gly m 2, Gly m 1A and Gly m 1B, respectively, and (2) pattern 2, present in 3 sera, consisted of a band with an estimated MW of 8.2-8.3 kD and four additional bands in a MW range of 25-36 kD. The remaining positive sera indicated very faint bands.

CONCLUSIONS

This study confirms that soybean hulls contain three main allergens with MWs of 8, 7.5 and 7 kD, and indicates additional higher MW allergens, which selectively bind specific IgE of the sera that do not react with the three low MW components. This dichotomous and nonoverlapping pattern of allergen recognition has not been previously described.

Increased positivity of skin test and allergenic stability of glycerinated soybean hull extracts

BACKGROUND

Results obtained from previous experiences with soybean hull antigens suggest that the addition of glycerine to the extract increases positivity of the skin test.

OBJECTIVE

The purpose of this study was to investigate the effect of this glycerine addition and the influence of different storage temperatures on the potency of soybean hull extracts.

METHODS

Twenty-two asthmatic patients admitted to emergency rooms during one of the soybean-related Barcelona asthma epidemics were evaluated 2 years after the last epidemic for: (1) sensitivity to prick test with glycerinated and non-glycerinated extracts, both fresh and stored at 4 degrees C, - 20 degrees C and - 70 degrees C for 30 days, and (2) specific IgE to a fresh hull extract. All extracts were also studied by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE).

RESULTS

No differences in positivities were detected for prick tests performed the same day of preparation between non-glycerinated (5/22; 22.7%) and glycerinated (4/22; 18.2%) extracts. After 30 days storage, positivities of prick test with non-glycerinated extracts stored at 4 degrees C did not significantly differ from the results obtained on the first day. However, prick tests performed with glycerinated extracts stored for 30 days showed increased positivity for the extracts stored at 4 degrees C (7/22; 31%) (P < 0.05) as well as for those stored at - 20 degrees C and - 70 degrees C (9/22; 40.9%) (P < 0.001). This latter percentage is similar to that of specific immunoglobulin E detected by radioimmunoassay (10/22; 45. 4%). Also, for the glycerinated extracts only, the quantitative response showed an increase in mean diameter of the induration at 30 days at the three temperatures, even though owing to the great standard deviation and limited number of patients, it was only significant for the extract stored at - 20 degrees C (P < 0.01). SDS-PAGE gel densitometry at 30 days demonstrated a loss of protein in the bands with a molecular weight higher than 66.2 kDa for non-glycerinated extracts stored at 4 degrees C.

CONCLUSIONS

The results of this study confirm previous observations with soybean hull allergen extracts and indicate that (1) storage of soybean hull extracts with glycerine addition for 30 days at the concentration studied (1:100 w/v) determines a significant increase in the positivity of skin tests, and (2) glycerine addition stabilizes soybean hull extracts at any of the temperatures studied.

Neoallergens in heated soybean hull

BACKGROUND

During the process of harvest, transport and storage, microbial and mold contamination can raise the temperature of soybeans to 75 degreesC or higher. The purposes of this study were (1) to evaluate the allergenicity of fresh and stored soybean hulls and (2) to ascertain whether heat alters the allergenicity of stored soybean hulls.

METHODS

Allergen extracts were prepared from (1) stored soybean hulls, (2) fresh soybean hulls and (3) stored soybean hulls heated to 37 degreesC (E1), 55 degreesC (E2) and 80 degreesC (E3) or kept at room temperature (E4) for 16 h. Individual serum from 68 soybean asthmatic (SA) subjects, 30 nonallergic subjects and two serum pools made from 4 SA sera and 4 sera from asthmatics not sensitive to soybean were studied. All sera and serum pools were assayed for content of specific IgE (radioallergosorbent test) and IgG4 (ELISA). The following additional studies were done for extracts E1-E4: (1) SDS-PAGE, (2) SDS-PAGE/Western blot for specific IgE and IgG4 using both serum pools, and (3) study of the effects of heat on inhibiting activity of the extracts prepared from stored soybean hulls using the pool of SA sera.

RESULTS

Test results demonstrated a reduced binding of specific IgE and IgG4 to fresh soybean hull extract compared to stored soybean hull extract, and an increased binding for heated extracts (E1-E3) compared to unheated ones (E4). Moreover, there was an increase in potency for IgE and IgG4 bindings for the heated (E1-E3) compared to unheated (E4) extract, as measured by the amount of protein to produce 50% inhibition. Several protein bands with a molecular weight (MW) higher than 20 kD were absent from the SDS-PAGE for E3 but were present in E1, E2 and E4, and a new protein band (MW 15.3 kD) appeared for E3 only. Two new protein bands, with MWs of 15.3 and 10 kD, which bind specific IgE, were present on Western blot and one of the 3 main soybean hull allergens, probably Gly m 2, disappeared in E3. IgG4 Western blot showed similar results, but only the 10 kD protein band was present.

CONCLUSION

The results demonstrate that soybean hull allergenicity is affected by heat, and suggest that the heat generated during storage and transport of soybeans could generate 2 new allergen determinants or increases in epitope exposure as a result of conformational changes. The significance of these new IgE and IgG4 binding proteins has yet to be determined.

Purification and characterization of a soybean hull allergen responsible for the Barcelona asthma outbreaks. II. Purification and sequencing of the Gly m 2 allergen

BACKGROUND

A low MW allergen from soybean hull, Gly m 1, with two isoallergens, Gly m 1 A and Gly m 1 B, was associated with the asthma outbreaks that occurred in Cartagena, Spain. Using sera of asthmatic epidemic patients (AEP) from Barcelona, three main soybean hull allergens, two of them with MWs and pIs identical to those reported for Gly m 1 A and Gly m 1 B, were identified.

OBJECTIVE

The purpose of this study was to purify and to study the N-terminal amino acid sequence of the third allergen, which has a MW of 8 kDa.

METHOD

The purification procedure combined the double dialysis method and preparative isoelectofocusing (IEF). Specific IgE determination to the fractions obtained demonstrated three peaks, one of them corresponding to the 8 kDa allergen. The pooled fractions containing this allergen were studied by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE), SDS-PAGE/Western blot and IEF/Western blot. Only a band with a MW of 8 kDa and a pI of 6 was obtained. Its allergenic activity was measured and it was demonstrated that the allergenicity of soybean hull correlates with the presence of the 8 kDa allergen. The N-terminal amino acid sequence of the first 20 amino acids, which was registered at the PIR Data Submission as the N-terminal partial sequence of Gly m 2, was determined according the Edman degradation method.

RESULTS

Gly m 2 N-terminal amino acid sequence lacks homology with that reported for the allergen Gly m 1 but has a homology of 71% with a storage protein from cotyledon of Vigna radiata (cow pea) and 64% with a "disease response protein' from Pisum sativum (green pea). These results suggest that Gly m 2 in soybeans could protect against diseases which affect soybean plants.

CONCLUSION

This study demonstrates the existence of another soybean hull allergen, Gly m 2, partially responsible for the soybean asthma outbreaks that occurred in Barcelona, Spain.

Partial characterization of the silk allergens in mulberry silk extract

Although there have been reports of allergic reactions such as asthma and hypersensitivity pneumonitis to silk allergens (especially in oriental countries), these allergens have not been characterized. We report an in vivo and in vitro study of subjects allergic to silk, as well as a partial characterization of the allergens involved. Forty-one subjects with a clinical history of silk allergy who had asthma, allergic rhinitis or both, and who had a positive intradermal skin test to mulberry silk extract, were evaluated in the study. Four asthmatic subjects with negative skin tests and RASTs to mulberry silk extract were used as controls. RAST specific lgE was present in 37/41 (90%) subjects. SDS-PAGE of mulberry silk extract demonstrated 13 protein bands of less than 21-95 kD. lgE which bound to protein bands was present in 13/32 (41%) sera, twelve of which bound to a single protein with a molecular weight between 35.1 and 50 kD. A pool made with the four control sera did not react with any protein band. The patients allergic to silk showed evidence of sensitivity to mulberry silk extract, both in vivo and in vitro, but sera from 19/32 (59%) subjects did not have antibodies reactive with the mulberry silk extract immunoblot protein bands. The low avidity of the lgE may be responsible for this discrepancy between in vivo and in vitro results.

IgG subclass deficiencies associated with bronchiectasis

Only a small number of patients with IgG subclass deficiencies (IgGSD) have been observed to have bronchiectasis. Moreover, in the series of patients with bronchiectasis, IgGSD have not been found at any frequency, and the etiology of bronchiectasis remains unclear in 29 to 49% of cases. Serum concentrations of total IgG, IgA, and IgG subclasses as well as pulmonary function were measured in 65 patients (aged: 10 to 74 yr) with bronchiectasis of unknown etiology. An ELISA test was performed to quantify subclasses 1 through 4 using subclass-specific antihuman monoclonal antibodies. IgG subclass estimation in a healthy population with age-stratified normal ranges was derived from 100 adults, 37 children aged between 10 and 12 yr, and 27 adolescents aged between 13 and 16 yr. Serum concentrations of specific IgG antibodies to Haemophilus influenzae type b capsular polysaccharide (Hib-PRP) were also assayed by an ELISA test in 19 of the patients (10 with IgGSD and nine with non-IgGSD) and in 58 healthy individuals before and 3 wk after immunization with Hib-PRP conjugated to meningococcal outer membrane protein complex (OMPC). Thirty-one patients (48%) had low serum concentrations of one or more IgG subclasses (19 IgG2 deficiencies, 2 IgG3 deficiencies, 3 IgG4 deficiencies, and 7 combined subclass deficiencies). All patients showed increased levels of total IgG, IgG1, and IgA, but this rise was significantly higher in patients without IgGSD. Patients with IgGSD showed impaired antibody response to Hib-PRP compared with patients with non-IgGSD and the control group. IgGSD, particularly IgG2 deficiency, are not an unusual cause of bronchiectasis. Therefore, serum levels of IgG subclasses must be assayed whenever other causes of bronchiectasis have been ruled out.

Diagnosis of soybean-induced asthma

BACKGROUND

The role of soybean dust as a causal agent of asthma has been clearly established since the Barcelona asthma epidemics in the 1980s. The large number of patients who were first seen with asthma symptoms during those epidemics provided an excellent opportunity to study the possibilities of different diagnostic tests.

OBJECTIVE

This study was designed to evaluate the usefulness of the skin test and amplified ELISA technique for quantifying specific IgE in the diagnosis of soybean asthma.

PATIENTS AND RESULTS

Ninety epidemic asthmatic patients and 95 nonepidemic asthmatic patients were studied 2 years after the last epidemic. Results of prick tests and ELISAs for specific IgE with hull and dust extracts showed a significant difference between the two groups of patients (p < 0.001). Sensitivity and specificity of glycerinated prick test with hull extract in epidemic asthmatic patients were 57.7% and 95.3%, respectively, and ELISA values were 56.6% and 93.7%, respectively. Similar results were obtained with dust extracts.

CONCLUSION

Glycerinated skin prick tests and ELISAs with soybean hull and dust extracts have proved effective in the diagnosis of soybean asthma, even 2 years after the epidemics. Taking into account the sensitivity (90.5%) and specificity (93.7%) of ELISA test results for epidemic asthmatic patients found when the epidemic occurred, data from this study suggest that both tests may be very useful for the diagnosis of soybean dust-induced asthma.

[IgG subclasses in patients with symptomatic IgA deficiency]

BACKGROUND

Patients with IgA deficiency may be asymptomatic or may present recurrent infections mainly respiratory. A possible explanation for this variety of symptoms may be the association with a deficiency of IgG subclasses.

METHODS

Twenty-five patients with a symptomatic IgA deficiency with a mean age of 18 +/- 12 years were studied. The quantification of the IgG subclasses was performed by ELISA test with antisubclass specific monoclonal murine antibodies. Serum from 100 healthy adults was collected to determine normal values of the IgG subclasses.

RESULTS

Twenty-five (48%) had a deficiency of associated IgG subclasses (6 IgG2 deficiency, 1 IgG3, 3 IgG4 and 2 combined deficiency). The patient with a deficiency of associated IgG subclasses had more recurrent respiratory infections (chi 2, p < 0.03) and pneumonias (chi 2, p < 0.04). This group also had a greater FEV1 alteration (Student-t test, p < 0.04).

CONCLUSIONS

Patients with symptomatic IgA deficiency frequently present IgG subclass deficiency and are more likely to have recurrent respiratory infections and greater changes in pulmonary function.

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.

Preventing asthma epidemics due to soybeans by dust-control measures

BACKGROUND

The inhalation of soybean dust released during the unloading of soybeans into a silo caused outbreaks of asthma in Barcelona, Spain. This study was designed to determine morbidity due to asthma and serum IgE reactivity before and after the installation of filters in the silo.

METHODS

We measured soybean-allergen concentrations in 136 samples of air collected for 9 months before and 24 months after the installation of filters. We compared the number of days on which there was an unexpected increase in emergency room visits for asthma, the number of days on which the number of emergency room visits for asthma in one four-hour period was so high that it was unlikely to be due to chance, and the mean daily number of emergency room and intensive care unit admissions for asthma for a total of 60 months before and after filter installation. Serum IgE antibodies against soybean allergens were measured in 38 patients before and after filter installation.

RESULTS

The concentration of airborne soybean allergens on days when soybeans were unloaded decreased from 324 to 25 U per cubic meter after the installation of filters (P < 0.001). The number of days on which there was an unusually large number of visits to the hospital for asthma and the number of days on which asthma was epidemic both decreased significantly (both P < 0.001), from 29 to 6 and from 18 to 0, respectively. The mean daily number of emergency room and intensive care unit admissions for asthma on days when soybeans were unloaded decreased from 8.3 to 5.4 and from 0.26 to 0.01, respectively (both P < 0.001). The mean serum IgE antibody concentrations in the 38 patients studied decreased from 2 Pharmacia reference units per milliliter to 1 (P < 0.001).

CONCLUSIONS

Installing filters on silos to prevent airborne dissemination of allergenic soybean dust eliminates outbreaks of asthma caused by inhalation of the dust, thus supporting the idea that the avoidance of allergens helps prevent asthma.

Risk factors of soybean epidemic asthma. The role of smoking and atopy

Epidemics of emergency room admissions for asthma occurring in Barcelona during the period 1981 to 1987 were caused by inhalation of soybean dust. To investigate the risk factors that determined why some asthma patients became reactive to soybean and were consequently affected by the asthma epidemics of Barcelona but others did not do so, a case-control study was conducted during 1989, 2 yr after the cessation of asthma epidemics. Patients with asthma admitted in emergency room services during epidemic asthma days (n = 169) were compared with asthma patients admitted in the same services during nonepidemic days and who were never admitted during the epidemics (n = 147). Risk factors other than soybean exposure, namely skin reactivity against at least one common allergen (odds ratio [OR] 3.0, 1.7 to 5.3), age over 64 yr (OR 2.8, 1.4 to 6.0), cigarette smoking at the time of the epidemics (OR 2.3, 1.2 to 2.4), past smoking (OR 1.8, 0.9 to 3.7), and total immunoglobulin E (IgE) higher than 100 IU/ml (OR 1.7, 1.0 to 3.0), were found independently related to epidemic asthma. The role of smoking was especially important for those who had a positive skin reaction and were exposed to soybean dust (OR 7.9, 1.8 to 36.0). In this group, a dose-response pattern with pack-years was observed (p less than 0.01). The present findings suggest a multifactorial process for epidemic asthma, in which atopy and cigarette smoking played an important synergistic role. This has a preventive potential for IgE-related asthma.

[Normal values of the immunoglobulin G subclasses in an adult population. Importance in a study of their deficiency]

BACKGROUND

Quantification of the IgG subclasses (IgGS) requires highly sensitive and specific techniques since their molecular structure is more than 95% homologous. At present, ELISA and RIA are the most appropriate techniques; although the variability of these techniques and the possible ethnic differences in serum levels of IgGS oblige each laboratory to establish its own reference values in a normal population, a condition necessary for defining IgGS deficits.

METHODS

In the present study the normal serum values of IgGS in 100 healthy individuals were established. Serum quantification of the IgGS was performed by optimization of the indirect ELISA technique using AcMo and OMS reference standards H00-03 for the 4 subclasses, calibrated vs the OMS WHO 67/97 pattern.

RESULTS

Normal values observed for IgG1 were 2.61-10.81 g/l; IgG2, 1.12-4.08 g/l; IgG3, 0.22-2.88 g/l; and IgG4, 0.05-1.56 g/l obtained as of the mean +/- 2 SD for IgG1 and as of the extent of the values of the remaining 3 subclasses by following a non-normal distribution. The sensitivity of the technique was 0.05 g/l with mean intra and inter analysis coefficients of 3.5% and 10.7% respectively. The correlation between total IgG and the sum of the 4 subclasses showed a r = 0.894 (p less than 0.01).

CONCLUSIONS

The ELISA technique using AcMo and OMS reference standards is an adequate method for the quantification of the IgG subclasses. However, given the variability of this technique and in order to avoid error, strict working conditions, such as the use of control sera at 2 concentration levels, should be observed for the 4 IgGS in each of the analytic series and each series should also be duplicated.

[Evaluation and significance of circulating immunocomplexes and their correlation with other immunologic parameters in connective tissue diseases]

The presence of circulating immunocomplexes (CIC) was evaluated in several collagen diseases and in a control group of 100 healthy individuals. Three methods were used for their detection: binding to C1q in solid phase, binding to conglutinin in solid phase, and measurement of the serum capacity to solubilize an experimental immunocomplex. In the group of patients with systemic lupus erythematosus (SLE) significant differences were found for the three techniques (p less than 0.001) and also for activity (p less than 0.001). The most sensitive method was binding to C1q. The sensitivity of the three techniques for CIC was very low in the group of patients with systemic sclerosis, and the highest rate of positive results was found with binding to C1q (10%). In the group with hypersensitivity vasculitis and polyarteritis nodosa CIC were found in 71% of cases, more than one method being positive in 50%. The highest sensitivity was obtained with the conglutinin method (48%). In patients with temporal arteritis, significant differences were only found for conglutinin binding method (p less than 0.001), with low rates of positivity.