Current practice of allergy diagnosis and the potential impact of regulation in Europe

In the European Union (EU), the regulatory framework regarding diagnostic allergen extracts is currently in the process of being implemented at the national level. Due to these regulations, the initial and periodic renewal expenses for the registration of diagnostic allergen extracts may render extract production unprofitable. Consequently, many extracts may be at risk of removal from the market. The current survey, which was conducted by a task force of the European Academy of Allergy and Clinical Immunology, aimed to assess the current practice of allergy diagnosis in Europe. This survey revealed that skin tests continue to be the main diagnostic procedure and are used as the first option in almost two-third of all types of allergic diseases and in 90% of individuals suffering from respiratory allergies. Therefore, there is a need to ensure the availability of high-quality allergen extracts to maintain the common diagnostic procedures used by EU professionals. To reach this goal, it is necessary to align efforts and establish active partnerships between manufacturers, relevant scientific societies, consumer organizations and authorities to maintain the availability of these diagnostic tools.

Immunotherapy is allergen-specific: a double-blind trial of mite or timothy extract in mite and grass dual-allergic patients

BACKGROUND

One hundred years ago, Noon [Lancet 1911;1:1572-1573], using conjunctival provocation testing (CPT), was the first to demonstrate the effectiveness of subcutaneous immunotherapy (SCIT) in grass-allergic subjects with hay fever. In this centenary year, we present data that, by use of CPT and allergen-specific IgG, replicate this observation and additionally confirm the allergen specificity of SCIT by using a double-blind design employing either grass or mite SCIT in dual grass- and mite-allergic individuals.

METHODS

Twenty adults (11 females) with perennial rhinoconjunctivitis and exacerbation of symptoms during the grass pollen season and in the autumn had immediate skin and conjunctival sensitivity and raised specific IgE to both Dermatophagoides farinae and Phleum pratense. Participants were randomly assigned to either timothy or D. farinae immunotherapy for 3 years. CPT and specific IgG tests to both allergens were performed annually. After 3 years, subjects gave their blinded overall evaluation.

RESULTS

Six mild-to-moderate general reactions occurred in 2 timothy- and 4 mite-treated patients. Four of these patients and 2 other patients withdrew from the study. Seven patients in each group completed the study. After 3 years of immunotherapy, the timothy CPT threshold concentration had increased 16- fold in timothy-treated patients (p < 0.05; between-group change, p < 0.05). The increase in the mite CPT threshold in mite- compared to grass-treated patients was 31-fold (p < 0.05). The overall assessment of conjunctival sensitivity was highly significant in favour of treatment (p < 0.015), as was that of allergen-specific IgG (p < 0.0001).

CONCLUSIONS

Allergen immunotherapy is allergen species-specific, as judged by decreased conjunctival sensitivity and changes in allergen-specific IgG concentrations.

Specific immunotherapy has long-term preventive effect of seasonal and perennial asthma: 10-year follow-up on the PAT study

BACKGROUND

3-year subcutaneous specific immunotherapy (SIT) in children with seasonal allergic rhinoconjunctivitis reduced the risk of developing asthma during treatment and 2 years after discontinuation of SIT (5-year follow-up) indicating long-term preventive effect of SIT.

OBJECTIVE

We evaluated the long-term clinical effect and the preventive effect of developing asthma 7-years after termination of SIT.

METHODS

One hundred and forty-seven subjects, aged 16-25 years with grass and/or birch pollen allergy was investigated 10 years after initiation of a 3-year course of SIT with standardized allergen extracts of grass and/or birch or no SIT respectively. Conjunctival provocations were performed outside the season and methacholine bronchial provocations were performed during the season and winter. Asthma was assessed by clinical evaluation.

RESULTS

The significant improvements in rhinoconjunctivitis and conjunctival sensitivity persisted at the 10-year follow-up. Significantly less actively treated subjects had developed asthma at 10-year follow-up as evaluated by clinical symptoms [odds ratio 2.5 (1.1-5.9)]. Patients who developed asthma among controls were 24/53 and in the SIT group 16/64. The longitudinal treatment effect when adjusted for bronchial hyper-responsiveness and asthma status at baseline including all observations at 3, 5 and 10 years follow-up (children with or without asthma at baseline, n = 189; 511 observations) was statistically significant (P = 0.0075). The odds ratio for no-asthma was 4.6 95% CI (1.5-13.7) in favor of SIT.

CONCLUSION

A 3-year course of SIT with standardized allergen extracts has shown long-term clinical effects and the potential of preventing development of asthma in children with allergic rhinoconjunctivitis up to 7 years after treatment.

CLINICAL IMPLICATION

Specific immunotherapy has long-term clinical effects and the potential of preventing development of asthma in children with allergic rhino conjunctivitis up to 7 years after treatment termination.

Specific immunotherapy has long-term preventive effect of seasonal and perennial asthma: 10-year follow-up on the PAT study

BACKGROUND

3-year subcutaneous specific immunotherapy (SIT) in children with seasonal allergic rhinoconjunctivitis reduced the risk of developing asthma during treatment and 2 years after discontinuation of SIT (5-year follow-up) indicating long-term preventive effect of SIT.

OBJECTIVE

We evaluated the long-term clinical effect and the preventive effect of developing asthma 7-years after termination of SIT.

METHODS

One hundred and forty-seven subjects, aged 16-25 years with grass and/or birch pollen allergy was investigated 10 years after initiation of a 3-year course of SIT with standardized allergen extracts of grass and/or birch or no SIT respectively. Conjunctival provocations were performed outside the season and methacholine bronchial provocations were performed during the season and winter. Asthma was assessed by clinical evaluation.

RESULTS

The significant improvements in rhinoconjunctivitis and conjunctival sensitivity persisted at the 10-year follow-up. Significantly less actively treated subjects had developed asthma at 10-year follow-up as evaluated by clinical symptoms [odds ratio 2.5 (1.1-5.9)]. Patients who developed asthma among controls were 24/53 and in the SIT group 16/64. The longitudinal treatment effect when adjusted for bronchial hyper-responsiveness and asthma status at baseline including all observations at 3, 5 and 10 years follow-up (children with or without asthma at baseline, n = 189; 511 observations) was statistically significant (P = 0.0075). The odds ratio for no-asthma was 4.6 95% CI (1.5-13.7) in favor of SIT.

CONCLUSION

A 3-year course of SIT with standardized allergen extracts has shown long-term clinical effects and the potential of preventing development of asthma in children with allergic rhinoconjunctivitis up to 7 years after treatment.

CLINICAL IMPLICATION

Specific immunotherapy has long-term clinical effects and the potential of preventing development of asthma in children with allergic rhino conjunctivitis up to 7 years after treatment termination.

Five-year follow-up on the PAT study: specific immunotherapy and long-term prevention of asthma in children

BACKGROUND

A 3-year course of specific immunotherapy (SIT) in children with hay fever to grass and/or birch pollen significantly reduced the risk of developing asthma. To investigate the long-term preventive effect, we performed a follow up--2 years after termination of immunotherapy.

METHODS

A total of 183 children, aged 6-14 years with grass and/or birch pollen allergy could be investigated 2 years after discontinuation of SIT or no treatment. Conjunctival provocation tests (CPTs) and methacholine bronchial provocation tests were carried out during the season and winter after 5 years. The development of asthma was assessed by clinical evaluation.

RESULTS

The significant improvement in hay fever and CPT results observed after 3 years of SIT persisted at the 5-year follow-up. No difference in bronchial responsiveness to methacholine was found after 5 years because of spontaneous improvement during the follow-up period in the control patients. The immunotherapy-treated children had significantly less asthma after 5 years as evaluated by clinical symptoms [odds ratio 2.68 (1.3-5.7)] in favor of SIT for prevention of development of asthma and significantly less patients reported an increase in asthma scores (P < 0.01).

CONCLUSION

Immunotherapy for 3 years with standardized allergen extracts of grass and/or birch shows long-term clinical effect and preventive effect on development of asthma in children with seasonal rhinoconjunctivitis.

Variability of airborne cat allergen, Fel d1, in a public place

Allergen exposure is a risk to develop an IgE-mediated sensitization. The amount of allergen inhaled per unit time should be related to the amount present in the air, i.e. airborne allergen. Thus, measuring allergen levels in the air would be more relevant than measuring allergen levels in dust. Allergens are present in the air in very minute quantities and usually become airborne after disturbance. Large variation of allergen levels have been found in dust. In this study, we measured variability of airborne cat allergen, Fel d1, in a public place using a high-volume air-sampler. We also studied the distribution and relationship between dust and airborne cat allergens in homes and schools. Air samples were collected at three different airflow rates, i.e. 55, 40, and 30 m3 of air per hour. The concentration of airborne Fel d1 in the community gymnastic hall varied from 1 to 10 pg/m3 within a period of 3 weeks, at airflow rates 55-30 m3/h. The coefficient of variation for repeated samplings was 14-43% (day-to-day variation) and 27-38% (within-day variation). As expected, higher levels of airborne cat allergens were found in homes with cats than in cat-free environments. There was a significant relationship between cat allergen levels in dust and air (r=0.7, P<0.01). Our study demonstrates that when measuring airborne cat allergen a large variation is observed within a day and between days. The large variability of measurement may be explained by the disturbance in the environments. We suggest, that when exposure assessment is made the environment in question should be analyzed, if possible in several occasions.

'EUROPART'. Airborne particles in the indoor environment. A European interdisciplinary review of scientific evidence on associations between exposure to particles in buildings and health effects

The relevance of particle mass, surface area or number concentration as risk indicators for health effects in non-industrial buildings has been assessed by a European interdisciplinary group of researchers (called EUROPART) by reviewing papers identified in Medline, Toxline, and OSH. Studies dealing with dermal effects or cancer or specifically addressing environmental tobacco smoke, house dust-mite, cockroach or animal allergens, microorganisms and pesticides were excluded. A total of 70 papers were reviewed, and eight were identified for the final review: Five experimental studies involving mainly healthy subjects, two cross-sectional office studies and one longitudinal study among elderly on cardiovascular effects. From most studies, no definite conclusions could be drawn. Overall, the group concluded that there is inadequate scientific evidence that airborne, indoor particulate mass or number concentrations can be used as generally applicable risk indicators of health effects in non-industrial buildings and consequently that there is inadequate scientific evidence for establishing limit values or guidelines for particulate mass or number concentrations.

A revised nomenclature for allergy. An EAACI position statement from the EAACI nomenclature task force

This report has been prepared by an EAACI task force representing the five EAACI Sections and the EAACI Executive Committee composed of specialists that reflect the broad opinion on allergy expressed by various clinical and basic specialties dealing with allergy. The aim of this report is to propose a revised nomenclature for allergic and related reactions that can be used independently of target organ or patient age group. The nomenclature is based on the present knowledge of the mechanisms which initiate and mediate allergic reactions. However, the intention has not been to revise the nomenclature of nonallergic hypersensitivity.

A revised nomenclature for allergy. An EAACI position statement from the EAACI nomenclature task force

This report has been prepared by an EAACI task force representing the five EAACI Sections and the EAACI Executive Committee composed of specialists that reflect the broad opinion on allergy expressed by various clinical and basic specialties dealing with allergy. The aim of this report is to propose a revised nomenclature for allergic and related reactions that can be used independently of target organ or patient age group. The nomenclature is based on the present knowledge of the mechanisms which initiate and mediate allergic reactions. However, the intention has not been to revise the nomenclature of nonallergic hypersensitivity.

Biologic activity of Dermatophagoides siboney and Blomia tropicalis allergens in exposed and unexposed mite-allergic individuals. Effect of patient selection on the biologic standardization of mite extracts

BACKGROUND

This study aimed to investigate the influence of patient selection criteria, i.e., mite-allergic individuals exposed and not exposed to Dermatophagoides siboney and Blomia tropicalis, on the biologic activity of mite extracts. Determination of the potency of mite extracts in vivo requires selection of patients with a clinical history of mite allergy. In Scandinavia, there are some anamnestic criteria for mite allergy, whereas in the tropics, where patients are continuously exposed to high levels of mites, selection of patients with mite allergy by clinical history is difficult.

METHODS

A total of 210 Cuban asthmatics with continuous symptoms, and 43 Swedes with a clinical history of mite allergy were investigated. Skin prick tests were performed with D. siboney, D. pteronyssinus, D. farinae, B. tropicalis, Acarus siro, Lepidoglyphus destructor, and Tyrophagus putrescentiae extracts. For analysis of the biologic activity of mite extracts, Cuban patients were divided into four groups: 1) all patients skin-test-positive to mites 2) patients positive to mites, but not to other inhalant allergens 3) patients reacting most to the mite species analyzed 4) patients reactive only to mites and reacting most to the mite species analyzed. The biologic potency was calculated according to the Nordic Guidelines.

RESULTS

Due to cross-reactivity between mites, Swedish mite-sensitive patients, with a clear clinical history of mite allergy, but not exposed to D. siboney and B. tropicalis, were more skin reactive to these mites than were Cubans. The estimated potency increased gradually to >200% in group 4. In group 1 Cubans, the reactivity to all mites but B. tropicalis was lower than that in mite-sensitive Swedes.

CONCLUSIONS

According to the influence of patient selection criteria on the estimation of the potency of mite extracts, the determination of the biologic activity of allergenic extracts in subjects without a clear-cut clinical history should be replaced by new methods when available.

Mite allergens. Collection, determination, expression of results, and risk levels for sensitization and symptom induction

The presence of mite allergens in dust can be determined by counting mites at different stages of development in dust and by determination of the major allergen content (Der p 1 ) in dust and air, which is crucially important to allergic patients. For comparison of results, similar methods for collection of dust and air must be used. Due to their size, mite bodies and fecal particles are airborne only directly after disturbance. Special filters should be used for dust collection, and upholstered surfaces should be vacuumed for 2 min/m2 (minimum 4 m2) and hard surfaces for 1 min/m2 (minimum 8 m2). Heavy contaminations should be removed. Preferably, the method given in the ISAAC study should be followed. Samples should be deep-frozen for at least some days to kill the mites. ELISA techniques, preferably using polyclonal antibodies and antigen with all isoforms present, should be used for determination of allergens. The allergen load has been given in ng/g of dust, but allergen/m2 or per sample area should be preferred. Allergen in the air should be given in pg/m3. A tentative limit of 2000 ng/g was proposed for sensitization and asthma. This limit is still valid on a population basis, but recent data indicate that highly susceptible young children become sensitized at concentrations 10-100 times lower and that ng levels of cat allergen/m3, as found in schools, induce chronic asthma.

Cross-reactivity between Dermatophagoides siboney and other domestic mites. II. Analysis of individual cross-reacting allergens after SDS-PAGE and Western blotting inhibition

BACKGROUND

Dermatophagoides siboney (Ds) cross-reacted with other mite allergens in mite-allergic patients. The aim of this study was to investigate the cross-reactivity between individual allergens responsible for this cross-reactivity.

METHODS

The inhibition of IgE binding to Ds allergens was investigated by non-reducing SDS-PAGE and Western blotting. Nitrocellulose membranes were incubated with a pool of sera from mite-sensitive asthmatics, after the addition of serial dilutions of D. farinae (Df), D. pteronyssinus (Dp), D. microceras (Dm), Lepidoglyphus destructor (Ld), Tyrophagus putrescentiae (Tp), Acarus siro (As) and Blomia tropicalis (Bt). N-terminal amino acid sequences and amino acid analysis of the purified major allergens, Der s 1, 2 and 3, were performed after transfer to polyvinylidene difluoride membranes.

RESULTS

The inhibition was higher with Df(86%), Dp (54%) and Dm (49%) extracts than with Ld (20%), Tp (11%), As (18%) and Bt (6%). The dose-response inhibition showed a diverse pattern for the individual allergens. Despite the high cross-reactivity between the pyroglyphid mites, some proteins of Ds were less inhibited, e.g. by the Df and Dp 80-kD protein, and by the Dm and Dp 52-, 37-, 30- and 14-kD allergens. The 65-, 62-, 37- and 30-kD proteins were always inhibited more than 50% by all the mite extracts at the maximum concentration used. The 80-, 52-, 43-, 27- and 14-kD proteins cross-reacted to a lesser extent. Individual allergens of Ds were much less inhibited by non-pyroglyphid mites. However, at the highest concentration, Ld also inhibited most of the Ds allergens. All the ten selected allergens were inhibited to some extent by the heterologous mite extracts. The N-terminal sequences of Der s 1, 2 and 3 allergens showed higher homology to Df and Dm than to Dp. The homology of the group 2 allergens was higher than that of the group 1 allergens.

CONCLUSION

The individual allergens of Ds were more similar to Df and Dm than to Dp. There was a limited and variable cross-reactivity with non-pyroglyphid mites. No single allergen was unique for Ds.

Concentrations of cat (Fel d1), dog (Can f1) and mite (Der f1 and Der p1) allergens in the clothing and school environment of Swedish schoolchildren with and without pets at home

To investigate whether our hypothesis that cat and dog owners bring allergens to public areas in their clothes was true or not, we studied the levels of Fel d1, Can f1, Der p1 and Der f1 in dust from the clothes and classrooms of children in a Swedish school. We also investigated the levels of allergen in different areas in the four classrooms used by the children. Thirty-one children were selected in four classes, forming three groups: cat owners, dog owners and children without a cat or dog at home. Furthermore, a group of children with asthma was included. Cat and dog allergens were detected in all 57 samples from clothes and classrooms. Mite allergen Der f1 was detected in low concentrations in 6 out of 48 and Der p1 in 5 out of 46 samples investigated. The concentrations of Can f1 were higher than those of Fel d1 in samples from clothes (geometric mean: 2676 ng/g fine dust and 444 ng/g) and classrooms (Can f1: 1092 ng/g, Fel d1: 240 ng/g). The dog owners had significantly higher concentrations of Can f1 (8434 ng/g fine dust) in their clothes than cat owners (1629 ng/g, p < 0.01), children without cat or dog (2742 ng/g, p < 0.05) and children with asthma (1518 ng/g, p < 0001). The cat owners did not have significantly higher levels of Fel d1 (1105 ng/g) in their clothes compared to the other three groups. (D: 247 ng/g, nCnD: 418 ng/g) but the levels were significantly higher than for all children without a cat at home (345 ng/g, p < 0.05). No concentrations of mite allergen and low concentrations of Fel d1 and Can f1 were found in the children's hair. There were significantly higher concentrations of Fel d1 and Can f1 in dust from curtains than in samples from floors and bookshelves (p < 0.05). There was no significant difference between the allergen concentrations in samples from curtains and from desks and chairs, including the teachers' chairs, the only upholstered furniture in the rooms. Our results support the hypothesis that cat and dog owners bring allergens to public areas in their clothes and support other studies showing that textiles and upholstered furniture function as reservoirs of cat and dog allergens. Thus, children with asthma and other allergic diseases will be exposed to cat and dog allergens at school and by contact with pet owners, even if they avoid animal allergens at home.

Purification and IgE binding capacity of Der s 3, a major allergen from Dermatophagoides siboney

BACKGROUND

Sensitization to the house dust mite Dermatophagoides siboney has been demonstrated in asthmatic patients. Previously, Dermatophagoides siboney group 1 and group 2 allergens, named Der s 1 and Der s 2, respectively, have been purified.

OBJECTIVES

The aim of this study was to purify and to study the IgE reactivity of 30 kDa component, suspected to correspond to group 3 allergens.

METHODS

The protein was purified by affinity chromatography using anti-Der f 3 monoclonal antibodies and semi-preparative SDS-PAGE. The IgE binding capacity of the purified fractions was tested with sera from 106 mite-sensitive asthmatic patients using a modified chemiluminiscent method.

RESULTS

Affinity chromatography resulted in fractions containing the 30 kDa component which was further purified to homogeneity by SDS-PAGE. Seventy-three per cent of the sera showed IgE reactivity to this protein, indicating that it is a major allergen. The protein also reacted with anti Der f 3 polyclonal antibodies and had tryptic activity. There were differences in the reactivity to Der s 3 according to the age of the patients.

CONCLUSION

Based on the frequency of IgE reactions and the reactivity with antibodies directed to Der f 3, it is proposed to name this 30 kDa allergen from D. siboney, Der s 3.

Asthma, bronchial hyperreactivity and mediator release in children with birch pollinosis. ECP and EPX levels are not related to bronchial hyperreactivity

BACKGROUND

Symptoms of allergic asthma are triggered by allergen exposure inducing allergic inflammation and hyperreactivity of the bronchi.

OBJECTIVES

To investigate the possible relationship between clinical symptoms and signs of asthma, i.e. bronchial variability as measured by peak expiatory flow rate (PEFR), bronchial hyperreactivity (BHR) and mediators of allergic inflammation.

METHODS

Twenty-eight children with pollinosis, but no obvious history of asthma, were studied at three occasions, i.e. before, during and after (autumn) the birch pollen season. Twelve children sensitive to birch pollen were considered as the case group. Sixteen children, who were only clinically sensitive to grass pollen, served as controls. Subjective symptoms of asthma were recorded by visual analogue scale, BHR was estimated by methacholine bronchial provocation tests, bronchial variability PEFR and circulating mediators of inflammation, i.e. eosinophil cationic protein, eosinophil protein X, myeloperoxidase and tryptase in serum.

RESULTS

Bronchial hyperreactivity and by PEFR was more pronounced after than during the season (P < 0.01), whereas eosinophil mediators and the peak expiratory flow rate increased during the season (P < 0.05). Except for between PEFR variability and BHR in the autumn (r = 0.45; P = 0.014), no correlations were found. However, in the autumn, the majority of children were still hyperreactive in the bronchi and showed PEFR variability but the levels of eosinophil mediators in serum had returned to normal levels.

CONCLUSION

Signs and symptoms of asthma did not correlate with serum levels of mediators of allergic inflammation. Bronchial hyperreactivity and PEFR variability persisted after the pollen season when signs of bronchial inflammation had disappeared. We hypothesize that eosinophil mediators and other markers of allergic inflammation disappear after the late-phase reaction, whereas BHR persists. This would explain the lack of correlation between the levels of eosinophil mediators in serum and symptoms of asthma and BHR.

Estimation of skin prick test reactions with a scanning program

We evaluated a new method of computer-based scanning of skin prick test wheal areas. To test the calibration of the program, we scanned five constructed circles of exactly defined areas between 5 and 255 mm2. One of these circles was scanned in different degrees of contrast (modes), the middle mode being used in the other experiments. We also investigated the inter- and intraoperator variation. Finally, results obtained by measuring diameters of wheals and by the new method of area determination were compared for 82 histamine and 75 egg wheals. The areas found agreed well with the real areas (P < 0.01) (mean 97.4-100.8%), except for the smallest wheal (5mm2) (NS). Areas obtained in the "middle position" closely resembled the real area. The intraoperator coefficient of variation (c.v.) was 1.4% (0.3-4.3), the day-to-day c.v. was 1.9% (0.2-5.3), and the interoperator c.v. was 2.3% (0.7-5.7), with a higher c.v. for small areas. Histamine and egg wheals were significantly larger with the diameter method (126% and 129%, respectively) than with the area method. The difference between the methods was most pronounced for small wheal areas. The c.v. of the scanning method was significantly lower than that of the diameter method. The new program was precise and is recommended for registration of skin test reactions in scientific trials. Although the scanner works well and has high precision, the major problem in skin testing seems still to be the reproducibility of the skin test technique employed.

Allergens of horse dander: comparison among breeds and individual animals by immunoblotting

Some patients who are allergic to horses have reported that they can tolerate certain breeds, and the presence of breed-specific allergens has been suggested. Breeders and patients with asthma have claimed that Bashkir horses are nonallergenic. We used sodium dodecylsulfate-polyacrylamide gel electrophoresis and immunoblotting to determine IgE-binding profiles of extracts of dander obtained from horses of several breeds. We found considerable inter-breed and within-breed variation but no breed-specific allergens. Danders from all breeds investigated contained the most important allergens, and the allergenic content of dander from Bashkir horses was similar to that of other breeds. Difference in scale production could account for differences in sensitivity to breeds and individual horses.

Sensitization to Dermatophagoides siboney, Blomia tropicalis, and other domestic mites in asthmatic patients

Mite species adapted to warm, humid climates are commonly found in house dust in the tropics. In Cuba, Dermatophagoides pteronyssinus, D. siboney, and Blomia tropicalis are the most common and abundant mite species in house dust. To investigate the pattern of sensitization of Cuban asthmatic patients to common mite species, we skin-prick-tested (SPT) 148 patients with a clinical history of asthma and possible mite allergy, and determined specific IgE antibodies against mite allergens (D. pteronyssinus, D. farinae, D. siboney, B. tropicalis, Acarus siro, Lepidoglyphus destructor, Tyrophagus putrescentiae, and Glycyphagus domesticus). The prevalence of positive SPT was high to D. siboney (88%), D. pteronyssinus (87%), A. siro (85%), B. tropicalis (85%), and D. farinae (83%). The largest skin reactions were obtained with D. siboney and B. tropicalis extracts. The skin test response to the D. siboney extract correlated to those of D. farinae, D. pteronyssinus, B. tropicalis, and A. siro. The highest IgE levels were found to Dermatophagoides species and B. tropicalis. IgE to D. siboney and B. tropicalis were found in 97% and 96% of the patients, respectively. The prevalence of specific IgE to the other mites studied varied from 46 to 65%. D. siboney and B. tropicalis are important sensitizers among asthmatic patients in Cuba.

Allergen avoidance in a day-care center

The predominant sensitizing allergens in Swedish asthmatic children are furred pet animals. Poor ventilation and increased indoor humidity cause accumulation of pet allergens indoors. Indirect contacts with cats also increase pet allergen exposure. We investigated whether the concentration and the total amount of cat (Fel d I) and dog (Can f I) allergen in dust from various surfaces in a day-care center were influenced by extensive renovation, installation of a new ventilation system, ventilation of floors, and avoidance by families and personnel of direct and indirect contacts with pets. The cleaning routine in the day-care center was changed extensively after renovation. Old mattresses, pillowcases, curtains, sofas, and soft toys were removed, and new material were purchased. Dust was collected from various surfaces before and after renovation from table and chair surfaces, floors, curtains, mattresses, pillows, cushion-like toys, and sofas on five occasions during a 12-month period. Fel d I and Can f I allergen levels were determined by sandwich ELISA. The reduction in the total amount of both Fel d I and Can f I/sampling area was more pronounced than the reduction in the concentration of allergen/g of dust. After renovation, the mean cat and dog allergen concentration was decreased by six and 10 times, respectively. After 1 year, the total amount of cat allergen was lower in all areas (from 24 ng to < 1 ng/sampling area, P < 0.05). Already at the first sampling after renovation, the total amount of dog allergen had decreased more than 10 times. In a previous study, we found the median concentration of cat and dog allergen to be 10-30 times higher in ordinary day-care centers. Our present study demonstrates that children changing from a normal center to the renovated center would be exposed to much lower levels of cat and dog allergen. Combined measures such as installation of mechanical ventilation, ventilated floors, regular extensive cleaning, and, probably most important, avoidance of direct and indirect contacts with pets, should decrease cat and dog allergen exposure in day-care centers.

Characterization of allergenic components from house dust mite Dermatophagoides siboney. Purification of Der s 1 and Der s 2 allergens

BACKGROUND

Allergic reactions to house dust mites of the genus Dermatophagoides play an important role in the pathogenesis of asthma and other atopic diseases. Dermatophagoides siboney has been described as a species from Cuba. Together with D. pteronyssinus and Blomia tropicalis, it is frequently found in house dust from homes of asthmatics.

OBJECTIVES

The aim of this study was to investigate the allergenic composition from the house dust mite D. siboney.

METHODS

The characterization of D. siboney extract was performed by SDS-gPAGE and immunoblotting. Purification of individual components was performed by affinity chromatography.

RESULTS

At least 16 components between 13 and 98 kDa stained by Coomassie Blue were found. Using a panel of 35 sera from atopic mite sensitive patients 13 components reacted to different extent with patient IgE. Two components, 25 and 14 kDa, bound to specific IgE strongly and frequently, i.e. 80 and 91% of the patients, respectively. Affinity chromatography using crossreacting monoclonal antibodies to group 1 and 2 allergens resulted in purified preparations of 25 and 14 kDa proteins, which showed IgE-binding with the majority of the human sera when tested by immuno-dot.

CONCLUSION

Based on the IgE binding profile of D. siboney and on the capacity to react with crossreacting monoclonal antibodies for groups 1 and 2, it is proposed to name these two allergens, 25 and 14 kDa, Der s 1 and Der s 2, respectively.

Crossreactivity between Dermatophagoides siboney and other house dust mite allergens in sensitized asthmatic patients

BACKGROUND

The role of Pyroglyphid mites in IgE-mediated sensitization has been well established. Although mites belonging to the genus Dermatophagoides dominate in the acarofauna of domestic dust, non-pyroglyphid mites might also be of clinical importance. In Cuba, Dermatophagoides siboney is found in dust coexisting with D. pteronyssinus and Blomia tropicalis. Dermatophagoides farinae is not found. Storage mites, such as Acarus siro, Lepidoglyphus destructor and Tyrophagus putrescentiae, might also be present.

OBJECTIVES

The aim of this study was to investigate the allergenic relationships among the mites present in the environment of allergic patients in Cuba.

METHODS

The crossreactivity between an extract of D. siboney and the above mentioned six mites was studied by specific IgE inhibition, using sera of mite-sensitive patients after incubation with serial dilutions of D. siboney.

RESULTS

The inhibitory effect of D. siboney extract was more pronounced against D. farinae, 91%, than against D. pteronyssinus, 62%. Specific IgE to B. tropicalis, A. siro, L. destructor and T. putrescentiae were inhibited to a much lesser extent, i.e. between 47 and 58%. The correlation between IgE to D. siboney and IgE to D. pteronyssinus and D. farinae was of 0.92 and 0.90, respectively. A weaker correlation was found between D. siboney and L. destructor (0.7), A. siro (0.67), B. tropicalis (0.54) and T. putrescentiae (0.51).

CONCLUSION

Thus, D. siboney seems to be most closely related to D. farinae.

Atopic sensitization and respiratory symptoms among Polish and Swedish school children

Allergic sensitization and symptoms from the airways in relation to air pollution were compared in 10-12-year-old school children (n = 1113) from urban Konin in central Poland and both urban and rural parts of Sundsvall in northern Sweden. The measurements included parental questionnaires, skin-prick tests and serial peak flow measurements during 2 weeks with simultaneous monitoring of outdoor air pollutants. The skin-prick test technique was validated by IgE antibody determinations. The levels of common industrial pollutants, SO2 and smoke particles were much higher in Konin than in urban Sundsvall and the levels of NO2 were similar. Various respiratory symptoms were more often reported among school children in Konin (except for wheezing and diagnosed asthma). Multiple logistic regression analyses yielded the following increased odds ratios for children in Konin as compared with the reference group (rural Sundsvall): chest tightness and breathlessness 3.48 (95% confidence interval 2.08-5.82), exercise-induced coughing attacks 3.69 (95% confidence interval 1.68-8.10), recurrent episodes of common cold 2.79 (95% confidence interval 1.53-5.09) and prolonged cough 4.89 (95% confidence interval 2.59-9.23). In contrast, as compared with rural Sundsvall, the adjusted odds ratio for a positive skin-prick test was decreased in Konin, but increased in urban Sundsvall, 0.58 (95% confidence interval 0.37-0.91) and 1.67 (95% confidence interval 1.15-2.42) respectively. The study confirms that living in urban, as compared with rural areas, is associated with an increased prevalence of respiratory symptoms and sensitization to allergens. These differences could be explained by air pollution. Respiratory symptoms were more common in a similar urban group of Polish children who were exposed to even higher levels of air pollution. These children, however, had a much lower prevalence of sensitization to allergens, as compared with the Swedish children. This indicates that differences in lifestyle and standard of living between western Europe and a former socialist country influences the prevalence of atopy.

Effects of immunotherapy with a purified standardized allergen preparation of Dermatophagoides farinae in adults with perennial allergic rhinoconjunctivitis

Immunotherapy (IT) was performed for 12 months with a purified and standardized preparation of Dermatophagoides farinae. Twenty adults with rhinoconjunctivitis sensitive to house-dust mite were given IT, and a similar group of 11 patients served as open controls. A total of 512 injections were given. Twenty-eight episodes of allergic side-effects occurred, 13 general and 15 local, most of them during the initial incremental dose period. No severe reactions started later than 30 min after the injection. One patient suffered anaphylactic shock. In this patient, specific antibodies fell immediately, followed by an increase within 1 week. The therapy group improved significantly in relation to the open controls in patients' subjective evaluation of symptoms (P < 0.028) and skin (P < 0.0001) and conjunctival (P < 0.001) sensitivity. Specific IgE increased in controls (P < 0.0001) but not in IT-treated patients during the "mite season"; that is, there was a significant difference in change during the observation period (P < 0.0001). There was also a difference in change of specific IgG between the groups during the first 4-5 months and the whole year (P < 0.0001), but not from 4-5 months to 12 months. In contrast to changes in antibody titers (IgG, P = 0.04), changes in conjunctival (P < 0.01) and especially skin sensitivity (P < 0.005) correlated well with subjective improvement. This implies that the skin prick test and the conjunctival test can be recommended for follow-up of IT.(ABSTRACT TRUNCATED AT 250 WORDS)