Allergen-induced histamine release in intact human skin in vivo assessed by skin microdialysis technique: characterization of factors influencing histamine releasability

BACKGROUND: The purposes of the study were to characterize allergen-induced histamine release in intact human skin in vivo by using a novel microdialysis technique and to study covariates influencing histamine releasability. METHODS: Hollow microdialysis fibers were inserted into the upper dermis in 15 timothy-sensitivity subjects. Up to 12 fibers were inserted in each subject. Each fiber was perfused with Krebs-Ringer's solution at a rate of 3.0 microliters/min. Three to four serial dilutions of allergen were applied to the skin by intracutaneous injections or skin prick test above individual fibers. Samples were collected in two 2-minute fractions before skin challenge and in 10 consecutive samples for 20 minutes after skin challenge. Histamine was assayed spectrofluorometrically. RESULTS: A significant dose-response relationship for histamine release was demonstrated with intracutaneous tests and skin prick tests. The time to reach peak histamine release after an intracutaneous test was 4 to 8 minutes, compared with 12 to 14 minutes for a skin prick test. Histamine release correlated significantly with wheal size. Intrasubject coefficient of variation on histamine release was about 20%. A substantial intersubject variation in histamine releasability was observed. Seventy to seventy-five percent of the variation could be accounted for by a combination of gender, total and allergen-specific IgE, and an in vitro basophil histamine release test. CONCLUSIONS: Using a skin microdialysis technique, we have described in detail histamine release in intact human skin by allergen. The microdialysis method proved to be a reproducible technique for monitoring histamine release in allergic skin reactions and for studying histamine releasability of skin mast cells in vivo.     

Factors influencing immediate responses to intradermal allergen administration in patients with respiratory allergy

BACKGROUND: Immediate skin reactions to allergens are influenced by several factors, such as the amount of administered allergen, the level of specific IgE, releasability of mast cells and hyperresponsiveness of the target organ. METHODS: For the evaluation of factors influencing immediate skin response to intradermal allergen administration, we measured the wheal size 15 min after intradermal injection of 0.01-0.02 ml of the following agents: whole-body extract of Dermatophagoides farinae, 1,000 allergy units/ml; histamine, 0.1 mg/ml, and codeine sulfate, 0.09% in saline, and determined total IgE level, specific IgE and IgG subclass antibodies to D. farinae in 53 patients with respiratory allergy. RESULTS: Multiple regression analysis for factors influencing wheal size after intradermal injection of D. farinae, specific IgE antibody level to D. farinae and wheal size after intradermal administration of histamine showed statistically significant results (R2 = 0.42739, p = 0.0000; R2 = 0.50243, p = 0.0185, respectively). Multiple regression analysis for factors influencing wheal size after intradermal administration in the group with high levels of specific IgE to D. farinae (RAST class 3 or more) showed that wheal size after intradermal administration of codeine was the only factor exerting a statistically significant influence (p = 0.0119). CONCLUSION: Based on the above results, we can state that immediate responses to intradermal allergen administration were influenced by the level of specific IgE and hyperresponsiveness of the target organ to histamine, but that the immediate skin allergic responses in the presence of high levels of specific IgE were partially but significantly influenced by the releasability of skin mast cells.     

Oral contraceptives and risk of venous thromboembolism: impact of duration of use

BACKGROUND: At therapeutic dosage, cetirizine and ebastine induce significant inhibition of skin reactivity to histamine. The consistency of their efficacy, that is, efficacy with the least interindividual variability among subjects, has not been carefully assessed, however. OBJECTIVE: To compare the consistency and efficacy of these antihistamines on skin reactivity. METHODS: Twenty-four healthy volunteers participated in a randomized double-blind crossover study. The areas of wheals and flares induced by increasing (0, 5, 10, 50, 100, 200, and 300 mg/mL) histamine concentrations, administered by prick tests, were measured before and four hours after intake of 10 mg of each antihistamine, allowing concentration-response curves to be established. The threshold histamine concentrations inducing wheal areas of 3 mm2 (positivity) were calculated by interpolation. The coefficient of variation (SD/mean %) was used to evaluate the consistency of the response. RESULTS: Pretreatment concentration-response curves were similar, and threshold concentrations identical (0.29 mg/mL and 0.34 mg/mL for cetirizine and ebastine, respectively). For both, curves were lower after treatment than before. After cetirizine, the threshold concentration was significantly higher (217 mg/mL) than after ebastine (0.82 mg/mL) (P < .001), and total inhibition of the wheal reaction was observed in 21 of 24 patients at the lowest histamine concentration and in 17 of 24 at the highest. Ebastine never totally inhibited reaction, even to 5 mg/mL of histamine. Over the entire concentration-response curve, the coefficient of variation for the wheal reaction was 6.3% for cetirizine and 72.6% for ebastine, and, for flares, 11.0% and 83.7%, respectively. Hence, variability was much lower after cetirizine. CONCLUSION: Our study shows clearly that the efficacy of a single therapeutic dosage of cetirizine is consistently good for suppression of cutaneous reactivity to histamine in healthy volunteers. The need for ebastine to metabolize into the active carebastine might explain its lesser consistency.     

High-dose therapy with peripheral blood stem cell (PBSC) support using an innovative mobilization regimen in patients with high-risk primary or chemoresponsive metastatic breast cancers

BACKGROUND: Epidemiologic studies are necessary to determine the prevalence of allergic diseases. This varies widely depending on allergen preparations and patients studied. OBJECTIVE: To investigate the prevalence of atopic disease, skin test reactivity, total and specific IgE to common allergens, and other variables in a sample of students from Málaga, southern Spain. METHODS: Three hundred sixty-five students (age 17.9 +/- 1.18) were interviewed by an allergist. Skin prick tests were performed with Dermatophagoides pteronyssinus, Artemisia vulgaris, Plantago lanceolata, Chenopodium album, Olea europaea, Phleum pratense, Parietaria judaica, Cynodon dactylon, Alternaria tenuis, and cat dander. Total and specific IgE to D. pteronyssinus, Olea, and Parietaria were determined. RESULTS: Of all subjects studied, 19.9% suffered from rhinoconjunctivitis, 4.1% rhinoconjunctivitis plus asthma, 3.1% asthma alone, and 0.8% atopic dermatitis; 46.4% had a positive skin test to at least one allergen (28.2% to D. pteronyssinus, 20.4% to Olea, 13.8% to Phleum); and 43% had total IgE > 100 kU/L and 44.7% a family history of atopy. Allergic symptoms were strongly associated with skin test positivities and family allergic history. Patients with asthma or skin prick test positive had higher total IgE values than others (P < .01). There was a significant correlation between specific IgE values and wheal size in skin test. CONCLUSIONS: Our findings confirm the high prevalence of atopic diseases, and the close relationship of skin tests reactivity (or presence of specific IgE) to allergens with symptoms of asthma and rhinitis. The presence of a family history of allergic diseases influences the development of positive skin tests and atopic illness. Dermatophagoides pteronyssinus and pollen of Olea europaea were found to be the most common allergens.     

Predictors of early- and late-phase reactions to bronchial allergen challenge

The influence of inhaled steroids and predictive factors on the response to bronchial allergen challenge (BCA) was evaluated in 80 asthmatics allergic to Dermatophagoides pteronyssinus (Der p). All underwent BCA with Der p and measurement of early (EAR) and late asthmatic reaction (LAR). The cumulative dose of allergen producing 20% fall in FEV1 in the EAR (PD20) was calculated. Bronchial histamine provocation, conjunctival provocation test (CPT), and skin prick test with Der p extract were performed. Specific IgE to Der p in serum (RAST), blood eosinophil (EOS) count, serum eosinophil cationic protein, and eosinophil protein X were measured. Thirty patients (38%) were treated with inhaled steroids. All patients had at least a 20% fall in FEV1 in EAR. Some 42% of nonsteroid- and 33% of steroid-treated patients had LAR with fall in peak flow of at least 20%. For patients not treated with steroid, 35% of variation in PD20 was explained by RAST and histamine reactivity, and 53% of variation of observed PD20 could be predicted. The baseline FEV1, EOS, and EAR explained 28% of variation in LAR, and 28% of variation in observed LAR could be predicted. For patients treated with steroids, 38% of variation in PD20 was explained by EOS and histamine reactivity, and only 18% of variation of observed PD20 could be predicted. For patients treated with steroids, it was impossible to predict LAR. We conclude that to achieve a quantitative estimation of allergen-specific EAR and LAR, BCA cannot be replaced by the tests used in this study. Treatment with inhaled steroids modifies the response to BCA, making quantitative prediction of EAR less accurate and prediction of the magnitude of LAR impossible.     

Long-term oral corticosteroid therapy does not alter the results of immediate-type allergy skin prick tests

BACKGROUND: Medications can modulate the results of skin prick tests (SPTs). Short-term corticosteroid therapy does not alter IgE-mediated skin tests, but the impact of long-term oral corticosteroid therapy on SPT results is unclear. A prospective study was carried out in patients with steroid-dependent asthma who received oral corticosteroids for a long period to determine whether this treatment reduced skin test reactivity. METHODS: Thirty-three patients with steroid-dependent asthma (median age, 59 years) were compared with 66 patients with asthma who served as a control group, matched for age, sex, and atopic status. SPTs with codeine phosphate and a screening battery of standardized allergen extracts were performed before commencement and after at least 1 year of daily oral prednisone treatment (median duration, 2 years; median daily dose, 20 mg). RESULTS: Fifteen patients with corticosteroid-dependent asthma were allergic before treatment, and their sensitization was not changed by long-term treatment with oral corticosteroids. The median wheal diameters induced by codeine phosphate were similar in both groups. The median wheal diameters induced by allergens, and more specifically, by Dermatophagoides pteronyssinus and D. farinae were similar in both groups and did not change in the steroid group after treatment. CONCLUSIONS: Systemic corticosteroid therapy (prednisone, 10 to 60 mg/day) for 2 or more years does not seem to alter SPT reactivity.     

Diagnostic problems before specific immunotherapy in patients with late-summer seasonal allergic rhinitis

Skin prick tests were performed on 245 patients with late summer seasonal allergic rhinitis, and of these patients, 135 specific serum IgE test were performed. On the basis of skin prick test results, 94% of the patients were found to be sensitive to Ragweed: 18% of these patients had monosensitisation to Ragweed, and 56% were sensitive not only to Ragweed but also to Mugwort. The correlation between results of skin prick tests and specific serum IgE tests was found to be very good (95%) with Ragweed antigen experiencing no problem in the diagnostic process before immunotherapy. However, in 48% of patients with positive skin prick tests to Mugwort the specific serum IgE was found to be negative. Before immunotherapy, a specific nasal provocation test was performed on 12 of these patients with Mugwort to examine the real sensitivity of the shock-organ. This careful allergen research will demonstrate which components of allergen extract should be used for immunotherapy in late summer seasonal allergic rhinitis patients.     

Lack of interference in skin tests by histamine in food extracts

Because histamine occurs naturally in some food products, quantitative analysis of the histamine content of extracts of food used for skin testing seemed desirable to determine its effect in the production of positive reactions. Up to 200 nanograms of histamine per milliliter were found in some food extracts. When the extracts are diluted to 1:100 and 1:1000 W/V for skin testing the amount of histamine which would be injected in a intradermal skin test is one-thousandth of the amount required to produce a significant wheal. Therefore the histamine content of the foods analyzed is too small to be of practical concern and not enough to give nonspecific wheal reactions in intradermal tests using extracts of 1/1000 or 1/100 W/V concentrations. Nonspecific reactions in skin tests are probably most often due to use of food extracts of unnecessarily high concentration.     

Scorpion stings in Spain. Popular therapies, proverbs and pharmacopoeias]

There is evidence that bronchial responsiveness to allergen is quantitatively correlated with bronchial responsiveness to nonspecific stimuli in subjects with allergic asthma. This association has been questioned in occupational asthma due to low molecular weight substances. It was the aim of this study to assess the quantitative association of bronchial responsiveness to methacholine (MCh) and platinum salts (Pt), in the form of hexachloroplatinic acid, in workers with occupational asthma due to platinum salts. Fifty seven subjects with exposure to Pt, work-related asthma, and a positive bronchial challenge with Pt, underwent skin prick tests with Pt and bronchial challenge with MCh. Using the provocation concentration causing a > or = 50% fall in specific airway conductance (PC50sGaw(Pt)) as dependent variable, anamnestic data (period from first symptoms to removal, period between removal from exposure and diagnosis, and smoking), season of the investigation, skin prick tests with environmental allergens, total immunoglobulin E (IgE), skin reactivity to Pt (Pt concentration causing a 2 mm wheal), and PC50sGaw(MCh) were included as independent variables for regression analysis. Fifty two subjects (91%) showed a PC50sGaw(MCh) < 8 mg.mL-1 (geometric mean for all subjects 1.6 mg.mL-1). Responsiveness to Pt varied widely between subjects (geometric mean of PC50sGaw 9 x 10-5 mol.L-1, range 2 x 10-7 to 10-2 mol.L-1). There was no univariate correlation between bronchial responsiveness to MCh and Pt, but there was a correlation between skin reactivity to Pt and PC50sGaw(Pt) (r = 0.6). This association could not be improved by considering PC50sGaw(MCh), the period from first symptoms to removal, or the period between removal from exposure and diagnosis. The parameters that showed the highest (negative) associations with PC50sGaw(Pt) were skin reactivity to Pt and the period between removal from exposure and diagnosis (r = 0.65). We conclude that there is a moderate association between bronchial responsiveness to platinum salts and skin reactivity to platinum salts. However, there is no association between methacholine responsiveness and bronchial responsiveness to allergen in occupational asthma due to platinum salts.     

"Allergen engineering": variants of the timothy grass pollen allergen Phl p 5b with reduced IgE-binding capacity but conserved T cell reactivity

One problem of conventional allergen-specific immunotherapy is the risk of anaphylactic reactions. A new approach to make immunotherapy safer and more efficient might be the application of engineered allergens with reduced IgE-binding capacity but retained T cell reactivity. Using overlapping dodeca-peptides, the dominant T cell epitopes of the timothy grass pollen allergen Phl p 5b were identified. By site-directed mutagenesis outside these regions, point and deletion mutants were generated. Allergen variants were analyzed for IgE-binding capacity with sera of different grass pollen allergic patients by Western blotting, Dot blotting, and EAST inhibition test, and for histamine releasing capacity with peripheral blood basophils from different patients. The deletion mutants revealed significantly reduced IgE reactivity and histamine releasing capacity, compared with the wild-type Phl p 5b. Furthermore, in vivo skin prick tests showed that the deletion mutants had a significantly lower potency to induce cutaneous reactions than the wild-type Phl p 5b. On the other hand, T cell clones and T cell lines from different allergic patients showed comparable proliferation after stimulation with allergen variants and wild-type Phl p 5b. Considering their reduced anaphylactogenic potential together with their conserved T cell reactivity, the engineered allergens could be important tools for efficient and safe allergen-specific immunotherapy.     

Evaluation of the Brusini glaucoma staging system for follow-up in glaucoma

There is evidence that bronchial responsiveness to allergen is quantitatively correlated with bronchial responsiveness to nonspecific stimuli in subjects with allergic asthma. This association has been questioned in occupational asthma due to low molecular weight substances. It was the aim of this study to assess the quantitative association of bronchial responsiveness to methacholine (MCH) and platinum salts (Pt), in the form of hexachloroplatinic acid, in workers with occupational asthma due to Pt salts. Fifty-seven subjects with exposure to Pt, work-related asthma, and a positive bronchial challenge with Pt underwent skin prick test with Pt and bronchial challenge with MCH. Using the provocation concentration causing a > or = 50% fall in specific airway conductance (PC50sGaw(Pt)) as a dependent variable, anamnestic data (period from first symptoms to removal, period between removal from exposure and diagnosis, and smoking), season of the investigation, skin prick tests with environmental allergens, total immunoglobulin E (IgE), skin reactivity to Pt (Pt concentration causing a 2 mm wheal), and PC50sGaw(MCH) were included as independent variables for regression analysis. Fifty-two subjects (91%) showed a PC50sGaw(MCH) < 8 mg.mL-1 (geometric mean for all subjects 1.6 mg.mL-1). Responsiveness to Pt varied widely between subjects (geometric mean of PC50sGaw(Pt) 9 x 10(-5) mol.L-1, range 2 x 10(-7) to 10(-2) mol.L-1). There was no univariate correlation between bronchial responsiveness to MCH and Pt, but there was a correlation between skin reactivity to Pt and PC50sGaw(Pt) (r = 0.6). This association could not be improved by considering PC50sGaw(MCH), the period from first symptoms to removal, or the period between removal from exposure and diagnosis. The parameters that showed the highest (negative) associations with PC50sGaw(Pt) were skin reactivity to Pt and the period between removal from exposure and diagnosis (r = 0.65). We conclude that there is a moderate association between bronchial responsiveness to platinum salts and skin reactivity to platinum salts. However, there is no association between methacholine responsiveness and bronchial responsiveness to allergen in occupational asthma due to platinum salts.     

Plasma histamine changes during provoked bronchospasm in asthmatic patients

Seven patients with bronchial asthma underwent bronchial inhalation challenge with aerosolized allergen extracts and methacholine. Simultaneously, venous blood samples were collected and histamine was measured. Each patient was challenged on successive days with an allergen extract to which he had no skin-sensitizing antibody (skin test-negative allergen), followed by methacholine and skin test-positive allergen. Bronchospasm was not induced by inhalation of skin test-negative allergens but was observed in all patients after methacholine and in the majority of patients after skin test-positive allergens. No changes in plasma histamine were detected after challenges with methacholine and skin test-negative allergens. After challenge with skin test-positive allergens, significant rises in plasma histamine were detected in 5 of 7 patients. Plasma histamine was elevated within the first 5 min after inhalation of aerosolized allergen, and elevations persisted as long as 30 min. These studies showing that histamine increases significantly in the plasma during allergen-induced asthma in man suggest that histamine should be considered as at least one of the mediators of bronchospasm in allergic asthma. Bronchospasm induced by the cholinergic drug methacholine, unlike allergen-induced bronchospasm, is not associated with changes in plasma histamine.     

Filtration of airborne allergens in various households

The filtration system investigated in this study uses the thermic convection caused by radiators for the adsorption of airborne particles. The effect of this filtration system on the reduction of clinical symptoms of allergic bronchial asthma was tested as well as its capability in retaining airborne allergens, in particular those of the house dust mite Dermatophagoides pteronyssinus (D. pter.), which are responsible for this special kind of asthma. Dust samples were taken before and after the heating season in households of 36 persons with D. pter. caused asthma. Their mite content was investigated using mite flotation and direct microscopy, their guanine content using the Acarex-test. An allergen extract obtained from the filters was tested on its allergen content by RAST-inhibition. It could be observed that compared to the preceding heating season 55% of the volunteers felt an improvement of their asthmatic symptoms. It was possible to extract allergens of D. pteronyssinus, house dust and mould from the filters. All these results show the capability of the filters to adsorb house dust mite (HDM) allergens.     

The Darwinian evolution of health care

The aim of this study was to determine the aeroallergen sensitivity of allergic rhinitis patients. A total of 100 cases (female: 59, male: 41, aged between 10-59 years, mean age 27.9 years) who were diagnosed with allergic rhinitis by history and clinical presentation, underwent a prick skin test with 30 aeroallergens, and the important sensitizing allergens were assessed. Skin test reactivity showing > or = 3 mm wheal with erythema as the positive skin test, was recorded. The results of patients with positive skin tests follow. TREES: acacia 19%, mango 16%, coconut 12%. GRASSES: bermuda 17%, johnson 21%, timothy 16%, bahia 16% orchard 18%. WEEDS: pigweed 16%, kochia 14%. MOLDS: alternaria 11%, cladosporium 11%, aspergillus 12%, penicillium 16%, helminthosporium 16%, botrytis 15%, rhodotorula 20%, fusarium 26%, curvularia 26%, smut mix 11%, rust 9%. EPIDERMALS: cat 29%, dog 28%, feathers 37%. INDOOR ALLERGENS: house dust 72%, D. pteronyssinus 76%, D. farinae 79%, American cockroach 60%, German cockroach 41%, kapok 30%. Eighty-five percent of patients sensitive to house dust mites were positive to both D. pteronyssinus and D. farinae, indicating substantial cross-reactivity. The study shows that the house dust mite and the cockroach are important aeroallergen sensitizers among the Thai population, since more than half the patients were skin-test positive to the house dust mite and the cockroach.     

Affinity purification of the major bovine allergen by a novel monoclonal antibody

A monoclonal antibody was developed to the 20 kd major allergen of cow by immunizing mice with crude dander extract. The monoclonal antibody did not exhibit cross-reactivity to cat, dog, and horse dander extracts when studied by ELISA inhibition. The antibody was used in affinity chromatography for the purification of the 20 kd allergen from cow dander extract. Purity of the allergen was estimated to be 88%, and allergenic reactivity was verified by IgE immunoblotting and skin prick tests. After further purification with size-exclusion chromatography, the allergen was almost 100% pure. The isoelectric point of the double-purified allergen was determined to be 4.1. The amino acid composition was characterized by the predominance of acidic amino acids.     

Transient sensitization to house-dust mites: a study on the influence of mite exposure and sex

This study aimed to evaluate the prognosis of a previous positive skin test to house-dust mites (HDM) in relation to environmental exposure. A total of 115 children, 50 from Stockholm and 65 from northern Sweden, all with a previous (average 2.5 years) positive Phazet (Pharmacia AB, Uppsala, Sweden) skin prick test (SPT) to extracts of Dermatophagoides pteronyssinus (Dpt) and/or D. farinae (Df) were included. Dust samples were collected from the children's mattresses, and the total (Dpt, Df, and D. microceras [Dm]) amount of major mite allergen was measured by ELISA (50 children) and expressed as microgram allergen per gram of dust, or was measured by microscopy (65 children). The results of microscopic mite counts were transformed to approximate allergen levels as 2 micrograms equals 100 mites per gram of dust. Of 115 originally SPT-positive children, only 48 (48%) remained positive at retest, while the majority (58%) were SPT negative after 2 years. Among the 67 converted children, 11 were still exposed to mite allergen, but only to low concentrations (only one converted child being exposed above the suggested threshold level [TLV] of 2 micrograms/g), compared to 15/48 children still SPT positive who were exposed above the TLV. This shows that continued mite exposure is a major risk factor (OR = 30, CI 4.8-184) for continued positive SPT to HDM. A minor risk factor for continued sensitization was sex, boys having a higher risk than girls (OR = 2.2, CI 1.0-4.8). In conclusion, a surprisingly high rate of SPT conversion occurred, mainly as a result of a favorable indoor environment with low exposure to HDM and, to a lesser degree, as a result of sex. The present results support the view that the risk level of exposure is 2 micrograms mite allergen per gram of dust.     

Mite allergy in the tropics: sensitization to six domestic mite species in Cartagena, Colombia

Sensitization to the domestic mites Blomia tropicalis, Chortoglyphus arcuatus, Lepidoglyphus destructor and Aleuroglyphus ovatus was investigated in 77 subjects with clinical symptoms of asthma and/or allergic rhinitis and a positive skin prick test (wheal > or = 3 mm) to Dermatophagoides pteronyssinus and/or D. farinae. Seventy patients were skin test-positive to D. pteronyssinus and 73 to D. farinae. Serum samples from 29 nonallergic, skin test-negative individuals were used as negative controls. Specific IgE was determined by RAST and the results expressed as the % of the total counts bound (% TCB). A positive result (> or = 1% TCB) to D. farinae was detected in 89.6% of subjects, to B. tropicalis in 80.5%, to D. pteronyssinus in 75.3%, to C. arcuatus in 71.4%, to A. ovatus in 68.8% and to L. destructor in 59.7%. None of the controls had a positive RAST to any of the mite species. Different IgE binding patterns were observed among these subjects, suggesting sensitization to unique as well as common allergens in the different mite species. Sensitization to Pyroglyphidae (D. pteronyssinus and D. farinae) and non-Pyroglyphidae mites (B. tropicalis, C. arcuatus, L. destructor and A. ovatus) is common among allergic individuals in Cartagena. Extracts of these mites may be needed for a more accurate diagnosis and effective treatment of respiratory diseases due to mite allergy in tropical environments.     

House dust mite allergens and mite allergy in Copenhagen dwellings. A cross-sectional study

The aim of the study was to investigate the influence of various environmental factors on occurrence of house dust mite allergens and the influence of allergen exposure on mite allergy. Ninety-two persons from a population study filled in a questionnaire, were skin prick and lung function tested and dust samples were collected from their mattresses for analyses. Two out of five patients with asthma had a positive skin reaction to house dust mite allergen in contrast to five out of 87 non-asthmatics. Fifty-nine per cent of the dust samples contained (group 1) mite allergen > 2 micrograms/g dust. Such mattresses were older (median 7 years, range 1-22) than mattresses with less allergen (median 4 years, range 1-20). In the six bedrooms reported to be humid or mouldy, mattresses contained high concentration of mite allergens. No other parameter investigated could predict the allergen contents. In almost all cases dust analyses are crucial to be able to advise patients with house dust mite allergy.     

Individual allergens as risk factors for bronchial responsiveness in young adults

BACKGROUND: Bronchial responsiveness is known to be related to atopy, but the relative contribution of sensitisation to individual allergens in the UK, or whether serum total IgE is an independent risk factor, is unknown. METHODS: A random sample of 1864 men and women aged 20-44 years, drawn from family health service registers in Cambridge, Ipswich and Norwich, was invited to answer a detailed questionnaire, undergo skin prick tests and methacholine bronchial challenge, and provide a serum sample for measurement of total and specific IgE. The relation of bronchial responsiveness to risk factors was studied in 749 subjects (40.2%) with complete data. RESULTS: Bronchial responsiveness was increased in those sensitised to cat, D pteronyssinus, Timothy grass and Cladosporium, but decreased in subjects also positive to birch allergen. Additional skin prick tests added little information. Serum total IgE was not significantly related after adjustment for specific IgE to the five allergens. Increasing titres of specific IgE to D pteronyssinus were associated with increasing bronchial responsiveness. Specific IgE to Cladosporium had a prevalence of around 3%, but was associated with greatly increased responsiveness. Decreased baseline lung function was related (p < 0.001) to increased responsiveness. There was an interaction between age and smoking status, with lower responsiveness in older non-smokers. CONCLUSION: Atopy is the most important risk factor for bronchial responsiveness in this age group, but effects are not additive across all allergens. Research in reducing exposure to house dust mite should also address the role of Cladosporium sensitisation and exposure to indoor moulds.     

The mite allergen and allergoid stimulation of histamine secretion by mast cells

Rat peritoneal mast cells were incubated with serum from highly mite-sensitive patients. It was demonstrated that exposure of passive sensitized mast cells to allergen from mites Dermatophagoides farinae induced the release of histamine. Exposure of mast cells to 10 micrograms/ml and 50 micrograms/ml mite allergen resulted in an increase of histamine secretion to 48% of the basal level. The allergoid (formaldehyde-modified mite allergen) had poor histamine-releasing activity compared to allergen. The allergoid (50 micrograms/ml) induced a 2.5-fold decrease in histamine release. The allergen at the same concentrations and the same release as allergen in dose 0.1 microgram/ml.