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Background: The aim of the study was to characterize the kinetic accumulation of various inflammatory mediators in allergen‐challenged skin chambers applied on patients with pollen‐related allergic rhinitis/mild asthma. Methods: Skin blisters were induced on the forearms and challenged with allergen or phosphate‐buffered saline (PBS). Peripheral blood was drawn before and 8 h after challenge for analysis of differential cell counts, sVCAM‐1, and α2‐macroglobulin. Chamber fluids, collected at 1, 4, and 8 h after allergen application, were analyzed for differential cell counts, histamine, interleukin (IL)‐4, sVCAM‐1, and α2‐macroglobulin. Results: The number of recruited leukocytes was equal in allergen and PBS chambers; however, the numbers of eosinophils and lymphocytes were significantly (P≤0.05) elevated in allergen‐challenged chambers at 8 h. Compared to PBS chambers, allergen chambers contained significantly (P<0.01–0.05) higher levels of histamine (at 1 and 4 h), IL‐4 (at 4 and 8 h), α2‐macroglobulin (at 1 and 8 h), and sVCAM‐1 (at 1 and 8 h). In contrast to α2‐macroglobulin, levels of sVCAM‐1 in peripheral blood were significantly (P<0.05) increased at 8 h. Conclusions: Increased levels of sVCAM‐1 and IL‐4 in allergen‐challenged chambers, in parallel with increased recruitment of eosinophils and lymphocytes, points to the participation of IL‐4 and VCAM‐1 in the development of the late‐phase reaction. Increased levels of sVCAM‐1 in allergen‐challenged chambers probably reflects a combination of leakage and local production. Abbreviations: EDTA: ethylene diaminetetraacetic acid; FITC: fluorescein isothiocyanate; IL‐4: interleukin 4; LCR: late cutaneous reaction; LPR: late‐phase reaction; MFI: mean fluorescence... [ABSTRACT FROM AUTHOR]

Exposure to storage (nonpyroglyphid) mites has been increasingly recognized as a cause of asthma and rhinitis. Several species have been identified in Europe; e.g., Lepidoglyphus destructor, Acarus farris/siro, Tyrophagus spp., Glycyphagus domesticus, and Blomia tjibodas. Blomia tropicalis, on the other hand, predominates in subtropical and tropical areas. Studies from several countries have shown that IgE-mediated allergy in rural populations is of considerable importance and that storage mites are major allergens. Since these mites are found in homes, especially in regions with damp housing conditions, urban populations are at risk of becoming sensitized. Therefore, sensitization is not restricted only to those with occupational exposure. Several major allergens from storage mites have been identified and characterized. There seems to be a limited allergenic cross-reactivity between storage- and house dust mites. Molecular cloning has demonstrated that the Group 2 allergens from storage mites (Lep d 2 and Tyr p2) show more than 40% sequence identity with the Group 2 allergens from Dermatophagoides spp. The availability of a large number of recombinant dust mite allergens will make it possible to investigate their homology and the number of allergens required for the diagnosis and treatment of storage mite allergy. [ABSTRACT FROM AUTHOR]

We measured mast-cell tryptase in postmortem blood from 22 heroin addicts dying suddenly after injection. In 32%, the concentration of tryptase was elevated (≥10 μg/l). and the mean value of tryptase was significantly different from a control group dying from known, nonimmunologic causes (p <0.05). The increased tryptase concentrations indicate that death was preceded by systemic mast-cell degranulation. All victims of drug deaths had morphine in blood, most below 0.2 μg/ml. In 71% of the victims of drug-related deaths with tryptase values ≥10 μg/l, the intermediate degradation product, 6-monoacetyl-morphine, was not found in blood, whereas this was the case in only two victims with values below that cutoff point. This indicates that those with high tryptase concentrations survived longer than those with lower values. No correlation was found between the IgE levels and tryptase in either group, supporting the hypothesis that tryptase release was not mediated by an allergic reaction. The well-known property of opiates to stimulate unspecifically the liberation of histamine and other constituents of mast-cell granules offers one explanation of our observations. The results suggest that many heroin fatalities are caused by an anaphylactoid reaction. [ABSTRACT FROM AUTHOR]

The study aimed to determine whether inhalation of subclinical allergen doses-leads to a shift in the balance between T helper (Th) 1 and Th2 cells in asthmatic patients. Elevated IgE requires allergen-specific T cells producing cytokines such as interleukin (IL)-4 or IL-13. Interferon-gamma (IFN-γ) produced by Th1 cells counteracts the effects of IL-4. In nature, allergic persons are often exposed to low levels of allergen, leading to hyperreactivity, but not to acute allergic reactions. In this study, nine allergic persons inhaled low doses of allergen or placebo in a double-blind manner over seven consecutive weekdays. During the study, the bronchial responsiveness to histamine challenge increased, but no subject exhibited asthmatic symptoms. Blood was drawn on days 0, 1, 4, and 9, and the number of IL-4- and IFN-γ-producing cells was measured by enzyme-linked immunospot (ELISPOT) assay after in vitro stimulation with a low-dose phytohemagglutinin (PHA) mixed with the relevant allergen or with PHA alone. In three of the four subjects receiving allergen, the IL-4/IFN-γ ratio increased during the time of the study. No increase was seen in the placebo group. No increase was seen in serum IgE levels in any of the groups. We conclude that a shift in the balance between Th1 and Th2 cells can be detected in subjects exposed to subclinical allergen doses. [ABSTRACT FROM AUTHOR]

The objective of the present study was to investigate the potential of the long-acting β2-agonist salmeterol as an inhibitor of various components of IgE-mediated inflammation in man. For this purpose, we measured gross skin reactivity (diameters of wheal and flare reaction [WFR] and late cutaneous reaction [LCR]) as well as inflammatory cells, mediators, and protein in cutaneous suction blister chambers in eight subjects with allergic rhinitis. Blisters were induced, two on each forearm, by gentle suction and heating, and were unroofed 12 h later, after which plastic chambers were placed over the denuded area. The chambers were challenged for 2 h with antihuman IgE (titer 1: 10) in the presence and absence of salmeterol or terbutaline. Normal goat IgG served as negative control. Chamber fluids were removed hourly for the first 4 h, and this was followed by a 4-h incubation before final collection. Salmeterol (10-6 M) and terbutaline (10-5 M) injected intradermally 30 min before, as well as together with anti-IgE (titer 1:100). inhibited the WFRs by up to 30%. The effect of salmeterol on the ensuing LCR (75% inhibition at 24 h) tended to be more pronounced than the corresponding inhibition by terbutaline. Both salmeterol and terbutaline very effectively inhibited the anti-IgE-induced extravasation of α2-macroglobulin into skin chambers, with a significantly more sustained effect by salmeterol. Interestingly, only terbutaline reduced the histamine release evoked by anti-IgE. With the present experimental design, where both drugs were washed out from the chambers after 2 h, neither drug inhibited recruitment of leukocytes (including eosinophils). Taken together, salmeterol had a more sustained inhibitory effect than terbutaline on indices of IgE-mediated edema formation (late induration and plasma protein extravasation). On the other hand, under the present experimental conditions, salmeterol failed to reduce the histamine release (in contrast to terbutaline), and neither salmeterol nor terbutaline affected the recruitment of leukocytes. [ABSTRACT FROM AUTHOR]

ELISA (enzyme-linked immunosorbent assay) inhibition with a monoclonal antibody (mAb) (42B6) to Lepidoglyphus destructor was used to detect and quantify the storage-mite allergens in 30 dust samples collected from barns. Regarding the mite fauna, microscopic inspection of the barn dust and mite counts showed that L. destructor infested all 30 barns investigated (range 430-195 400 mites/g dust). In 29/30 barns, L. destructor constituted more than 70% of the Astigmata species. Acarus siro was found in 26 samples, the highest value being 16155 mites/g. No Dermatophagoides species were found. As to mites of the suborder of Prostigmata, species belonging to seven different families were detected. Besides the predominant L. destructor, allergens derived from other storage mites such as Glycyphagus domesticus, A. siro, and Tyrophagus putrescentiae have previously been assessed by this ELISA method. The correlation between number of mites and concentrations of mite antigen as measured by ELISA was assessed by linear regression (r² = 0.83). Thus, inhibition of mAb 42B6 in ELISA would seem to offer a simple and reliable method to detect levels of dust-mite species belonging to the Acaridae and Glycyphagidae families. [ABSTRACT FROM AUTHOR]

To investigate allergic rhinitis induced by two experimental provocation models, we compared local inflammation with markers of eosinophil activity in peripheral blood. Patients with strictly seasonal allergic rhinitis were selected and investigated outside the pollen season. An acute challenge with increasing doses of allergen every 15 min until symptoms occurred was performed in nine patients. Nasal lavage and blood samples were taken before and 4 and 24 h after challenge. After a 6-week washout period, 10 patients were submitted to 7 days of repeated low allergen exposures. One small dose (&ap; 1/100 of the acute dose) was given each day. Blood and lavage samples were taken prior to and after the period. As control four patients were challenged with diluent only. The acute challenge resulted in sneezing and nasal discharge and blockage and was accompanied by a rise in histamine and eosinophil cationic protein (ECP) in lavage fluid after 4 h and continuing after 24 h, when there also was a rise in the number of eosinophils and ECP in peripheral blood. The repeated low-dose exposures caused very few symptoms but produced increased ECP in the lavage fluid and a trend toward increased histamine concentration. There were no changes in ECP, intracellular EG2 binding, or number of eosinophils in the blood. No changes were seen in the control group. Our findings show that changes in eosinophil mediator release in nasal lavage can be seen after very low, but repeated, allergen exposures despite no, or minimal, clinical symptoms. [ABSTRACT FROM AUTHOR]

The natural humoral immune response to the dust mite Lepidoglyphus destructor was assessed by comparing the IgG1 and IgG4 responses elicited in allergic (n = 44) and healthy (n = 16) individuals in a farming population chronically exposed to this allergen. With the aid of an immunoblotting technique and ELISA, the sera were analyzed for anti-L. destructor antibodies. While the majority of sera from the allergy group displayed several bands for both IgG1 and IgG4, the nonatopic healthy group was negative as analyzed in immunoblotting. When they were analyzed in ELISA, there was a significantly higher response in the allergy group than in the healthy group for IgG4, but not for IgG1. Taken together, these results imply that the immune system of individuals spared from allergic reactions to L. destructor not only lacks IgE antibodies but also seems largely to "ignore" these allergens/antigens despite exposure. [ABSTRACT FROM AUTHOR]

Identification of persons with atopic allergy in a population is difficult if the pattern of sensitizing allergens is unique. Three new multiallergen tests. Professional Allergy Mixes (PAX) 1-3 (Pharmacia Diagnostics, Uppsala, Sweden), have recently been introduced to screen IgE-mediated allergy among farmers. PAX 1 contains animal danders and feathers, PAX 2 mites and insects, and PAX 3 pollens and molds. The value of these new tests for the determination of IgE-mediated allergy among farmers was compared with that of Phadiatop®, a test for general atopy. Of 440 farmers, 91 were positive to Phadiatop and 97 to any of PAX 1-3. None of the farmers were positive in all tests. Only 70/97 sera positive in RAST to PAX 1-3 had a positive Phadiatop, whereas of 91 sera positive in Phadiatop, 70 had specific IgE antibodies to PAX 1-3. The value of using either Phadiatop or PAX 1-3 is limited (sensitivity 74-79%), but, together, these four tests will detect almost all (95.9%) farmers with IgE-mediated sensitization and all (100%) with symptoms. We have also shown that the grain weevil Sitophilus granaries and the botfly Gasterophilus intestinalis are important sources of allergens in rural environments. [ABSTRACT FROM AUTHOR]

The mite fauna in hay dust of 16 farms located on the island of Gotland was analysed to establish whether there is a clear relationship between environmental exposure to storage mites and development of allergic symptoms. Eight of these farms belonged to farmers with respiratory symptoms related to barn dust (RS) and eight to healthy farmers (H). All farmers had previously participated in an epidemiological survey of hypersensitivity to respiratory allergens. The symptomatic farmers had not only a positive RAST to storage mites but they developed more than a 20% fall in FEV1 when challenged with Lepidoglyphus destructor (L. destructor) extract. The asymptomatic farmers were all negative in RAST to storage mites. Mites were found on all farms and the degree of infestation varied enormously, mite counts ranging from 75–150,000 mites/g dust. Five genera were detected but the different mite species were not represented on all farms. L. destructor was the dominating species on 13 of 16 farms. Samples from RS farms contained a significantly higher number of mites than H farms. The results of this study are in good agreement with our earlier studies showing that L. destructor is the most important allergen causing symptoms from both upper and lower airways among farmers. [ABSTRACT FROM AUTHOR]

Comparison of the clinical significance and allergenic cross-reactivity of Blomia kulagini (B. kulagini) and Lepidoglyphus destructor (L. destructor) was made on sera from Sweden and Brazil using the radio-allergo-sorbens test (RAST) and the RAST inhibition technique. RAST-positive sera were obtained from 53 allergic Swedish farmers and 31 allergic subjects from Brazil who were positive to B. kulagini and/or L. destructor. B. kulagini was shown to be a common cause of sensitization especially in Brazil. There was a fairly high correlation between positive RAST results to L. destructor and B. kulagini based on sura from both Sweden and Brazil. The highest RAST scores were found against L. destructor in Swedish sera and against B. kulagini in Brazilian sera. The RAST inhibition studies showed that the L. destructor extract was able to inhibit the B. kulagini system (a positive RAST to B. kulagini allergen disc) in Swedish but not in Brazilian sera. In contrast, the B. kulagini extract was only able to inhibit the L. destructor system in sent from Brazil and not in sera from Sweden. This study shows that results obtained with RAST inhibition are not entirely dependent on the overall specificity of the IgE antibodies in the patient's sera, since the more subtle specificity of the primarily sensitizing allergen will dominate. Thus, conclusions drawn regarding allergenic cross-reactivity are dependent on the populations tested, and conclusions on the existence or absence of cross-reactivity, e.g. between two species of mites may he contradictory. [ABSTRACT FROM AUTHOR]

Bronchial provocation studies with L. destructor (L. des.) extract were made on 12 farmers with asthma who were exposed daily to stored hay and grain and had positive radio-allergo- sorbent test (RAST) to L. des. All 12 farmers developed more than a 20% fall in FEV, to the extract. None of the symptomatic farmers who were also RAST positive to the L. des. culture medium developed an asthmatic reaction to the medium extract. Neither four healthy farmers nor two patients with asthma caused by D. pteronyssinus (D. pt.) responded to L. des. or the L. des. culture medium. Challenges with D. pt. extract were negative in two symptomatic farmers who were RAST positive to L. des. and negative to D. pt. The present study further supports our previous hypothesis that there is an IgE mediated immunological mechanism behind L. des-induced asthma in farmers and that atopic farmers are liable to develop occupational asthma caused by allergy to L. des. [ABSTRACT FROM AUTHOR]

Several species of storage mite have been shown to cause IgE-mediated sensitization. Monoclonal antibodies (mabs) have been raised against the storage mite Lepidoglyphus destructor, and one mab (42B6) immunoprecipitated a band of 39 kDa of L. destructor. To search for the frequency of IgE antibodies in patient sera against this allergen component, we modified a radioimmunoassay (RIA), 42B6 being used as capturing antibody. Twenty of 43 sera from farmers who were RAST positive to L. destructor (46.5%) were scored as positive in this assay. There was a moderate degree of correlation between positive RAST results to L. destructor and the 39-kDa allergen. Among 14 sera from Stockholm residents positive in RAST to both Dermatophagoides pteronyssinus and L. destructor, six detected the 39-kDa allergen component. However, three sera from urban subjects lacking IgE antibodies against both mite species also had IgE antibodies against the 39-kDa allergen. The present study demonstrates that the 39-kDa allergen of L. destructor is an important allergen, and that rural as well as urban subjects can become sensitized. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate and compare two commercially available in vitro tests for specific IgE antibodies against latex, the A la-STAT specific IgE assay (DPC) and the Pharmacia CAP System. Immunoglobulin E-mediated allergy to natural rubber latex has a number of far-reaching consequences for patients, regarding both their occupational situation and safety in medical care. The correspondences between the IgE-calibrator curves were good. In two out of three DPC assays, there was no significant difference between the response values for the two lowest calibrators.

Background: It is well established that early diagnosis of allergic disease is warranted., Methods: In a prospective birth cohort study (BAMSE) 3743 children at 4 years of age were included. Children were classified as having any allergic disease, e.g. asthma, suspected allergic rhinitis (suspAR), eczema or oro-gastro-intestinal symptoms with questionnaire. Blood was obtained from 2612 of these children and analysed for IgE antibodies (ab) towards 14 common food and airborne allergens., Results: Positive IgE ab results were found in 38% of the children with any allergic disease, whereas such IgE ab results were found in 17% among those without any allergic disease. Furthermore, among children with any allergic disease the median summated IgE ab levels were 10.7 kU(A)/l compared with 1.5 kU(A)/l among those without such symptoms. The highest IgE ab levels were found to birch, peanut, cat and horse. When the sum of the IgE-ab levels towards the selected allergens was at least 34 kU(A)/l, or, alternatively, more than four allergen tests were positive, there was a 75% likelihood of identifying the individual with any allergic disease. To identify those with asthma, as well as those with suspAR, a significant interaction was found for the combination of the sum of IgE-ab levels and number of allergens positive at test. For eczema only, the number of positive allergens at test was associated to the likelihood of such disease., Conclusions: In children, 4 years of age, allergic disease was frequently not associated with the presence of single positive IgE antibody results, whereas increased IgE ab levels were significantly more prevalent among those with allergic disease. Thus, testing a certain profile of airborne and food allergens, and utilizing the sum of the IgE-ab levels in combination with the number of allergens positive at tests, may represent a more efficient diagnostic tool then to use just single positive IgE-ab results.

Background: Predatory mites are used as biological pesticides worldwide for control of spider mites and other pests in greenhouses. The aim of this study was to evaluate the impact of occupational exposure to Phytoseiulus persimilis and Hypoaspis miles on IgE sensitization among a large group of Swedish greenhouse workers and to examine the relationship between exposure and allergic asthma and rhinoconjunctivitis., Methods: A total of 96 greenhouse workers from the southern part of Sweden, who were using the predatory mites for control of pests, were investigated with a questionnaire and a medical examination including lung function test. Blood samples were taken to test for allergen-specific IgE antibodies to Phytoseiulus persimilis and Hypoaspis miles as well as to Tetranychus urticae, Dermatophagoides pteronyssinus/farinae and Tyrophagus putrescentiae., Results: Seventeen of the 96 workers were positive in ImmunoCAP to predatory mites: 17 to P. persimilis (17.7%) and 14 to H. miles (14.6%). Subjects sensitized to predatory mites were significantly more often atopic (13/17), defined as a positive Phadiatop, than those who lacked IgE against these mite species (17/79) (P <0.01). IgE antibodies to the red spider mite T. urticae were present among 23 subjects. Thirty-five of the investigated subjects displayed a positive ImmunoCAP to at least one of the investigated mite species. Furthermore, sensitization to any of the mites tested was significantly associated with asthma (OR=9.3) and rhinoconjunctivitis (OR=4.3)., Conclusions: IgE sensitization to predatory mites, P. persimilis and H. miles, is common among greenhouse workers. The findings stress the importance of improved allergen avoidance in greenhouse environments.

Background: Predatory mites are used as biological pesticides worldwide for control of spider mites and other pests in greenhouses. The aim of this study was to investigate if predatory and spider mites give rise to sensitization among greenhouse workers who use biological pesticides., Methods: Blood samples were collected from 31 greenhouse workers from Stockholm area who were using the predatory mites Phytoseiulus persimilis and Hypoaspis miles for control of pesticides. Immunoglobulin E (IgE) binding to extracts of P. persimilis and H. miles and of the spider mite Tetranychus urticae was analysed with sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting., Results: A total of 16 workers displayed IgE antibodies to one or more of the three mite species, 32% (n = 10) to P. persimilis, 52% (n = 16) to H. miles and 26% (n = 8) to T. urticae. At least 17 IgE binding components in the molecular weight ranging from 28 to >94 kDa were identified in P. persimilis. In H. miles, at least 11 components were detected, among them at least one major component at about 70 kDa. Twenty-four IgE binding components were found in T. urticae., Conclusions: In this study we have for the first time shown that the predatory mites P. persimilis and H. miles can cause IgE-mediated sensitization among greenhouse workers. The clinical relevance of sensitization to predatory mites needs to be investigated in further studies.

The study aimed to determine whether inhalation of subclinical allergen doses-leads to a shift in the balance between T helper (Th) 1 and Th2 cells in asthmatic patients. Elevated IgE requires allergen-specific T cells producing cytokines such as interleukin (IL)-4 or IL-13. Interferon-gamma (IFN-gamma) produced by Th1 cells counteracts the effects of IL-4. In nature, allergic persons are often exposed to low levels of allergen, leading to hyperreactivity, but not to acute allergic reactions. In this study, nine allergic persons inhaled low doses of allergen or placebo in a double-blind manner over seven consecutive weekdays. During the study, the bronchial responsiveness to histamine challenge increased, but no subject exhibited asthmatic symptoms. Blood was drawn on days 0, 1, 4, and 9, and the number of IL-4- and IFN-gamma-producing cells was measured by enzyme-linked immunospot (ELISPOT) assay after in vitro stimulation with a low-dose phytohemagglutinin (PHA) mixed with the relevant allergen or with PHA alone. In three of the four subjects receiving allergen, the IL-4/IFN-gamma ratio increased during the time of the study. No increase was seen in the placebo group. No increase was seen in serum IgE levels in any of the groups. We conclude that a shift in the balance between Th1 and Th2 cells can be detected in subjects exposed to subclinical allergen doses.

To investigate allergic rhinitis induced by two experimental provocation models, we compared local inflammation with markers of eosinophil activity in peripheral blood. Patients with strictly seasonal allergic rhinitis were selected and investigated outside the pollen season. An acute challenge with increasing doses of allergen every 15 min until symptoms occurred was performed in nine patients. Nasal lavage and blood samples were taken before and 4 and 24 h after challenge. After a 6-week washout period, 10 patients were submitted to 7 days of repeated low allergen exposures. One small dose (approximately equal to 1/100 of the acute dose) was given each day. Blood and lavage samples were taken prior to and after the period. As control four patients were challenged with diluent only. The acute challenge resulted in sneezing and nasal discharge and blockage and was accompanied by a rise in histamine and eosinophil cationic protein (ECP) in lavage fluid after 4 h and continuing after 24 h, when there also was a rise in the number of eosinophils and ECP in peripheral blood. The repeated low-dose exposures caused very few symptoms but produced increased ECP in the lavage fluid and a trend toward increased histamine concentration. There were no changes in ECP, intracellular EG2 binding, or number of eosinophils in the blood. No changes were seen in the control group. Our findings show that changes in eosinophil mediator release in nasal lavage can be seen after very low, but repeated, allergen exposures despite no, or minimal, clinical symptoms.

The natural humoral immune response to the dust mite Lepidoglyphus destructor was assessed by comparing the IgG1 and IgG4 responses elicited in allergic (n = 44) and healthy (n = 16) individuals in a farming population chronically exposed to this allergen. With the aid of an immunoblotting technique and ELISA, the sera were analyzed for anti-L. destructor antibodies. While the majority of sera from the allergy group displayed several bands for both IgG1 and IgG4, the nonatopic healthy group was negative as analyzed in immunoblotting. When they were analyzed in ELISA, there was a significantly higher response in the allergy group than in the healthy group for IgG4, but not for IgG1. Taken together, these results imply that the immune system of individuals spared from allergic reactions to L. destructor not only lacks IgE antibodies but also seems largely to "ignore" these allergens/antigens despite exposure.

Identification of persons with atopic allergy in a population is difficult if the pattern of sensitizing allergens is unique. Three new multiallergen tests, Professional Allergy Mixes (PAX) 1-3 (Pharmacia Diagnostics, Uppsala, Sweden), have recently been introduced to screen IgE-mediated allergy among farmers. PAX 1 contains animal danders and feathers, PAX 2 mites and insects, and PAX 3 pollens and molds. The value of these new tests for the determination of IgE-mediated allergy among farmers was compared with that of Phadiatop, a test for general atopy. Of 440 farmers, 91 were positive to Phadiatop and 97 to any of PAX 1-3. None of the farmers were positive in all tests. Only 70/97 sera positive in RAST to PAX 1-3 had a positive Phadiatop, whereas of 91 sera positive in Phadiatop, 70 had specific IgE antibodies to PAX 1-3. The value of using either Phadiatop or PAX 1-3 is limited (sensitivity 74-79%), but, together, these four tests will detect almost all (95.9%) farmers with IgE-mediated sensitization and all (100%) with symptoms. We have also shown that the grain weevil Sitophilus granarius and the botfly Gasterophilus intestinalis are important sources of allergens in rural environments.

Several species of storage mite have been shown to cause IgE-mediated sensitization. Monoclonal antibodies (mabs) have been raised against the storage mite Lepidoglyphus destructor, and one mab (42B6) immunoprecipitated a band of 39 kDa of L. destructor. To search for the frequency of IgE antibodies in patient sera against this allergen component, we modified a radioimmunoassay (RIA), 42B6 being used as capturing antibody. Twenty of 43 sera from farmers who were RAST positive to L. destructor (46.5%) were scored as positive in this assay. There was a moderate degree of correlation between positive RAST results to L. destructor and the 39-kDa allergen. Among 14 sera from Stockholm residents positive in RAST to both Dermatophagoides pteronyssinus and L. destructor, six detected the 39-kDa allergen component. However, three sera from urban subjects lacking IgE antibodies against both mite species also had IgE antibodies against the 39-kDa allergen. The present study demonstrates that the 39-kDa allergen of L. destructor is an important allergen, and that rural as well as urban subjects can become sensitized.

Comparison of the clinical significance and allergenic cross-reactivity of Blomia kulagini (B. kulagini) and Lepidoglyphus destructor (L. destructor) was made on sera from Sweden and Brazil using the radio-allergo-sorbent test (RAST) and the RAST inhibition technique. RAST-positive sera were obtained from 53 allergic Swedish farmers and 31 allergic subjects from Brazil who were positive to B. kulagini and/or L. destructor. B. kulagini was shown to be a common cause of sensitization especially in Brazil. There was a fairly high correlation between positive RAST results to L. destructor and B. kulagini based on sera from both Sweden and Brazil. The highest RAST scores were found against L. destructor in Swedish sera and against B. kulagini in Brazilian sera. The RAST inhibition studies showed that the L. destructor extract was able to inhibit the B. kulagini system (a positive RAST to B. kulagini allergen disc) in Swedish but not in Brazilian sera. In contrast, the B. kulagini extract was only able to inhibit the L. destructor system in sera from Brazil and not in sera from Sweden. This study shows that results obtained with RAST inhibition are not entirely dependent on the overall specificity of the IgE antibodies in the patient's sera, since the more subtle specificity of the primarily sensitizing allergen will dominate. Thus, conclusions drawn regarding allergenic cross-reactivity are dependent on the populations tested, and conclusions on the existence or absence of cross-reactivity, e.g. between two species of mites may be contradictory.

Bronchial provocation studies with L. destructor (L. des.) extract were made on 12 farmers with asthma who were exposed daily to stored hay and grain and had positive radio-allergo-sorbent test (RAST) to L. des. All 12 farmers developed more than a 20% fall in FEV1 to the extract. None of the symptomatic farmers who were also RAST positive to the L. des. culture medium developed an asthmatic reaction to the medium extract. Neither four healthy farmers nor two patients with asthma caused by D. pteronyssinus (D. pt.) responded to L. des. or the L. des. culture medium. Challenges with D. pt. extract were negative in two symptomatic farmers who were RAST positive to L. des. and negative to D. pt. The present study further supports our previous hypothesis that there is an IgE-mediated immunological mechanism behind L. des.-induced asthma in farmers and that atopic farmers are liable to develop occupational asthma caused by allergy to L. des..