IgE sensitization to Blo t 21 and Blo t 5 is associated with asthma in the tropics: a case-control study

BACKGROUND AND OBJECTIVES

Blomia tropicalis sensitization is associated with asthma in different tropical and sub-tropical countries; however, information about the specific molecular components associated with this disease is scarce. Using molecular diagnosis, we sought to identify B. tropicalis allergens associated with asthma in Colombia.

METHODS

Specific IgE (sIgE) to eight B. tropicalis recombinant allergens (Blo t 2/5/7/8/10/12/13 and 21) was determined using an in-house developed ELISA system in asthmatic patients (n=272) and control subjects (n=298) recruited in a national prevalencestudy performed in Colombian cities (Barranquilla, Bogotá, Medellín, Cali and San Andrés). Sample study included children and adults (mean age: 28±SD 17 years old). Cross-reactivity between Blot 5 and Blo t 21 was evaluated by ELISA-inhibition.

RESULTS

Sensitization to Blo t 21 (aOR: 1.9; 95% CI: 1.2 - 2.9) and Blo t 5 (aOR: 1.6; 95%CI: 1.1 - 2.5), but not Blo t 2, was associated with asthma. sIgE levels to Blo t 21 and to Blo t 5 were significantly higher in the disease group. Cross-reactivity between Blo t 21 and Blo t 5 is on average moderate; however, individual analysis indicates that may be high (>50%) in some cases.

CONCLUSIONS

Although Blo t 5 and Blo t 21 has been described as common sensitizers, this is the first report of their association with asthma. Both components should be included in molecular panels for allergy diagnosis in the tropics.

Rhinitis associated with asthma is distinct from rhinitis alone: The ARIA-MeDALL hypothesis

Asthma, rhinitis and atopic dermatitis (AD) are interrelated clinical phenotypes that partly overlap in the human interactome. The concept of "one-airway-one-disease", coined over 20 years ago, is a simplistic approach of the links between upper- and lower-airway allergic diseases. With new data, it is time to reassess the concept. This article reviews (i) the clinical observations that led to Allergic Rhinitis and its Impact on Asthma (ARIA), (ii) new insights into polysensitisation and multimorbidity, (iii) advances in mHealth for novel phenotype definition, (iv) confirmation in canonical epidemiologic studies, (v) genomic findings, (vi) treatment approaches and (vii) novel concepts on the onset of rhinitis and multimorbidity. One recent concept, bringing together upper- and lower-airway allergic diseases with skin, gut and neuropsychiatric multimorbidities, is the "Epithelial Barrier Hypothesis". This review determined that the "one-airway-one-disease" concept does not always hold true and that several phenotypes of disease can be defined. These phenotypes include an extreme "allergic" (asthma) phenotype combining asthma, rhinitis and conjunctivitis. Rhinitis alone and rhinitis and asthma multimorbidity represent two distinct diseases with the following differences: (i) genomic and transcriptomic background (Toll-Like Receptors and IL-17 for rhinitis alone as a local disease; IL-33 and IL-5 for allergic and non-allergic multimorbidity as a systemic disease), (ii) allergen sensitisation patterns (mono- or pauci-sensitisation versus polysensitisation), (iii) severity of symptoms and (iv) treatment response. In conclusion, rhinitis alone (local disease) and rhinitis with asthma multimorbidity (systemic disease) should be considered as two distinct diseases, possibly modulated by the microbiome, and may be a model for understanding the epidemics of chronic and auto-immune diseases.

2019 ARIA Care pathways for allergen immunotherapy

Allergen immunotherapy (AIT) is a proven therapeutic option for the treatment of allergic rhinitis and/or asthma. Many guidelines or national practice guidelines have been produced but the evidence-based method varies, many are complex and none propose care pathways. This paper reviews care pathways for AIT using strict criteria and provides simple recommendations that can be used by all stakeholders including healthcare professionals. The decision to prescribe AIT for the patient should be individualized and based on the relevance of the allergens, the persistence of symptoms despite appropriate medications according to guidelines as well as the availability of good-quality and efficacious extracts. Allergen extracts cannot be regarded as generics. Immunotherapy is selected by specialists for stratified patients. There are no currently available validated biomarkers that can predict AIT success. In adolescents and adults, AIT should be reserved for patients with moderate/severe rhinitis or for those with moderate asthma who, despite appropriate pharmacotherapy and adherence, continue to exhibit exacerbations that appear to be related to allergen exposure, except in some specific cases. Immunotherapy may be even more advantageous in patients with multimorbidity. In children, AIT may prevent asthma onset in patients with rhinitis. mHealth tools are promising for the stratification and follow-up of patients.

A recombinant cystatin from Ascaris lumbricoides attenuates inflammation of DSS-induced colitis

Helminthiasis may ameliorate inflammatory diseases, such as inflammatory bowel disease and asthma. Information about immunomodulators from Ascaris lumbricoides is scarce, but could be important considering the co-evolutionary relationships between helminths and humans. We evaluated the immunomodulatory effects of a recombinant cystatin from A. lumbricoides on an acute model of dextran sodium sulphate (DSS)-induced colitis in mice. From an A. lumbricoides cDNA library, we obtained a recombinant cystatin (rAl-CPI). Protease activity inhibition was demonstrated on cathepsin B and papain. Immunomodulatory effects were evaluated at two intraperitoneal doses (0.5 and 0.25 μg/G) on mice with DSS-induced colitis. Body weight, colon length, Disease Activity Index (DAI), histological inflammation score, myeloperoxidase (MPO) activity, gene expression of cytokines and cytokines levels in colon tissue were analysed. Treatment with rAl-CPI significantly reduced DAI, MPO activity and inflammation score without toxic effects. Also, IL-10 and TGF-B gene overexpression was observed in rAl-CPI-treated group compared to DSS-exposed control and healthy mice. Furthermore, a reduction in IL-6 and TNF-A expression was found, and this was confirmed by the levels of these cytokines in colonic tissue. In conclusion, rAl-CPI reduces inflammation in a mouse model of DSS-induced colitis, probably by increasing the expression of anti-inflammatory cytokines and reducing pro-inflammatory ones.

Manifesto on small airway involvement and management in asthma and chronic obstructive pulmonary disease: an Interasma (Global Asthma Association - GAA) and World Allergy Organization (WAO) document endorsed by Allergic Rhinitis and its Impact on Asthma (ARIA) and Global Allergy and Asthma European Network (GA2LEN)

Evidence that enables us to identify, assess, and access the small airways in asthma and chronic obstructive pulmonary disease (COPD) has led INTERASMA (Global Asthma Association) and WAO to take a position on the role of the small airways in these diseases.

Starting from an extensive literature review, both organizations developed, discussed, and approved the manifesto, which was subsequently approved and endorsed by the chairs of ARIA and GA²LEN. The manifesto describes the evidence gathered to date and defines and proposes issues on small airway involvement and management in asthma and COPD with the aim of challenging assumptions, fostering commitment, and bringing about change.

The small airways (defined as those with an internal diameter <2 mm) are involved in the pathogenesis of asthma and COPD and are the major determinant of airflow obstruction in these diseases. Various tests are available for the assessment of the small airways, and their results must be integrated to confirm a diagnosis of small airway dysfunction.

In asthma and COPD, the small airways play a key role in attempts to achieve disease control and better outcomes. Small-particle inhaled formulations (defined as those that, owing to their size [usually <2 μm], ensure more extensive deposition in the lung periphery than large molecules) have proved beneficial in patients with asthma and COPD, especially those in whom small airway involvement is predominant.

Functional and biological tools capable of accurately assessing the lung periphery and more intensive use of currently available tools are necessary. In patients with suspected COPD or asthma, small airway involvement must be assessed using currently available tools. In patients with subotpimal disease control and/or functional or biological signs of disease activity, the role of small airway involvement should be assessed and treatment tailored. Therefore, the choice between large- and small-particle inhaled formulations must reflect the physician’s considerations of disease features, phenotype, and response to previous therapy. This article is being co-published in Asthma Research and Practice and the World Allergy Organization Journal.

EAACI Molecular Allergology User's Guide

The availability of allergen molecules ('components') from several protein families has advanced our understanding of immunoglobulin E (IgE)-mediated responses and enabled 'component-resolved diagnosis' (CRD). The European Academy of Allergy and Clinical Immunology (EAACI) Molecular Allergology User's Guide (MAUG) provides comprehensive information on important allergens and describes the diagnostic options using CRD. Part A of the EAACI MAUG introduces allergen molecules, families, composition of extracts, databases, and diagnostic IgE, skin, and basophil tests. Singleplex and multiplex IgE assays with components improve both sensitivity for low-abundance allergens and analytical specificity; IgE to individual allergens can yield information on clinical risks and distinguish cross-reactivity from true primary sensitization. Part B discusses the clinical and molecular aspects of IgE-mediated allergies to foods (including nuts, seeds, legumes, fruits, vegetables, cereal grains, milk, egg, meat, fish, and shellfish), inhalants (pollen, mold spores, mites, and animal dander), and Hymenoptera venom. Diagnostic algorithms and short case histories provide useful information for the clinical workup of allergic individuals targeted for CRD. Part C covers protein families containing ubiquitous, highly cross-reactive panallergens from plant (lipid transfer proteins, polcalcins, PR-10, profilins) and animal sources (lipocalins, parvalbumins, serum albumins, tropomyosins) and explains their diagnostic and clinical utility. Part D lists 100 important allergen molecules. In conclusion, IgE-mediated reactions and allergic diseases, including allergic rhinoconjunctivitis, asthma, food reactions, and insect sting reactions, are discussed from a novel molecular perspective. The EAACI MAUG documents the rapid progression of molecular allergology from basic research to its integration into clinical practice, a quantum leap in the management of allergic patients.

IgE responses to Ascaris and mite tropomyosins are risk factors for asthma

BACKGROUND

The relationship between helminthiases and allergy is a matter of considerable interest and research. In the tropics, house dust mite exposure, a known risk factor for asthma, is frequently concurrent with helminth infections. It remains to be defined whether infection with the common roundworm Ascaris or its bystander immunological effects influence the prevalence and pathogenesis of asthma independently of mite sensitization.

OBJECTIVE

To investigate the relationship between the IgE responses to Ascaris and its purified allergens and the risk of asthma in a tropical country.

METHODS

A nested case-control study was performed in 356 subjects who reported current and past asthma symptoms (asthmatics) and 435 controls that had never experienced such symptoms. They were tested for serum levels of total IgE and specific IgE to Ascaris extract, Asc s 1 (ABA-1), Asc l 3 (tropomyosin) and GST (glutathione transferase). In addition, specific IgE to Dermatophagoides pteronyssinus, Blomia tropicalis and their tropomyosins Der p 10 and Blo t 10 was measured. Sensitization was defined as a positive specific IgE result to any extract or recombinant allergen.

RESULTS

Sensitization to Ascaris and D. pteronyssinus was independently associated with asthma after adjustment for age, gender, socio-economic stratum, city and other IgE levels (adjusted ORs: 2.17; 95% CI 1.37-3.42 and 2.46; 95% CI 1.54-3.92), respectively. There was also a significant association with sensitization to the highly allergenic and cross-reactive tropomyosins Asc l 3, Blo t 10 and Der p10 (aORs: 1.76; 95% CI 1.21-2.57, 1.64; 95% CI 1.14-2.35 and 1.51; 95% CI 1.02-2.24), respectively.

CONCLUSION AND CLINICAL RELEVANCE

IgE responses to Ascaris are associated with asthma symptoms in a population living in the tropics. Sensitization to the cross-reactive Ascaris and mite tropomyosins partially underlies this finding. These results have potential relevance in asthma diagnosis and management.

IgE cross-reactivity between Ascaris lumbricoides and mite allergens: possible influences on allergic sensitization and asthma

Nematode infections such as Ascariasis are important health problems in underdeveloped countries, most of them located in the tropics where environmental conditions also promote the perennial co-exposure to high concentrations of domestic mite allergens. Allergic diseases are common, and most of patients with asthma exhibit a predominant and strong IgE sensitization to mites. It is unknown whether co-exposure to Ascaris lumbricoides and the domestic mites Blomia tropicalis and Dermatophagoides pteronyssinus potentiates Th2 responses and IgE sensitization, thereby modifying the natural history of allergy. Recently, we obtained experimental evidence of a high cross-reactivity between the allergenic extracts of these invertebrates, involving well-known allergens such as tropomyosin and glutathione transferases. There is indirect evidence suggesting that the clinical impact of these findings may be important. In this review, we discuss the potential role of this cross-reactivity on several aspects of allergy in the tropics that have been a focus of a number of investigations, some of them with controversial results.

Allergenicity of Ascaris lumbricoides tropomyosin and IgE sensitization among asthmatic patients in a tropical environment

BACKGROUND

Ascaris lumbricoides induces a Th2 response and specific IgE synthesis in humans. This confers antiparasite immunity but could modify the natural history of allergic diseases in the tropics, justifying the study of its allergenic composition. We analyzed the allergenic properties of Ascaris tropomyosin and the frequency of sensitization in subjects exposed to the parasite.

METHODS

cDNA was obtained by reverse transcription PCR, cloned into pQE30-UA and purified as a 6× His-tagged protein. Equivalence with its natural counterpart was analyzed by cross-inhibition and liquid chromatography-tandem mass spectrometry. Specific IgE was measured by ELISA in 175 asthmatics and 170 nonasthmatics naturally exposed to the parasite and sensitized to the Ascaris extract.

RESULTS

The cDNA encoded 287 residues with high sequence identity with other invertebrate tropomyosins. The 40-kDa protein was recognized by human serum and affinity-purified anti-rBlo t 10 IgE. Specific IgE to tropomyosin could represent approximately 50% of the total IgE response to the extract. Ascaris tropomyosin induced wheal and flare in skin prick tests and histamine release from basophils. Although the prevalence of IgE to Ascaris tropomyosin was higher in asthmatic patients, logistic regression analysis suggested that this result was biased by sensitization to mites.

CONCLUSIONS

A. lumbricoides tropomyosin (Asc l 3) is a new allergen that binds specific IgE, induces mediator release from effector cells and is cross-reactive to mite tropomyosins. IgE reactivity to this allergen is very frequent in both asthmatic and normal subjects sensitized to Ascaris extract. The potential role of Ascaris tropomyosin in asthma pathogenesis in tropical regions should be further investigated.

Increased total and mite-specific immunoglobulin E in patients with aspirin-induced urticaria and angioedema

BACKGROUND

An increased prevalence of atopy has been observed in patients with intolerance of aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs).

OBJECTIVE

To investigate total and mite-specific immunoglobulin (Ig) E in serum from patients with hypersensitivity to NSAIDs and healthy controls.

METHODS

Patients who reacted to 2 or more chemically unrelated NSAIDs with urticaria and angioedema, confirmed by a double-blinded provocation test with aspirin, were skin tested with inhalant allergens. Total and specific IgE to Dermatophagoides pteronyssinus (Dp) and Blomia tropicalis (Bt) in the serum was quantified by enzyme-linked immunosorbent assay (ELISA) in patients and a control group of healthy blood donors.

RESULTS

One-hundred-and-fourteen patients and 74 controls were studied. Skin tests were positive in 95 patients (83.3%). Total mean IgE levels were 107.1 (91.3) IU/mL in controls and 161.0 (150.8) IU/mL in patients (P = .006). Mean (SD) levels of IgE to Dp were 0.210 (0.17) optical density (OD) units in controls and 0.473 (0.65) OD units in patients (P = .001). Levels of specific IgE to Bt were 0.230 (0.20) OD units in controls and 0.522 (0.8) OD units in patients (P =.0001). Positive ELISA results for IgE to Dp were found for 29.6% of controls and 70.4% of patients (P =.0001); the corresponding percentages for Bt were 32.4% of controls and 67.6 % of patients (P = .0001).

CONCLUSIONS

Cross-reactive patients with NSAID-induced urticaria and angioedema exhibit an increased prevalence of sensitization to Dp and Bt and increased total serum IgE. Further research is necessary to determine the reasons for this association.

IgE cross-reactivity between Ascaris and domestic mite allergens: the role of tropomyosin and the nematode polyprotein ABA-1

BACKGROUND

Analysis of cross-reactivity between the nematode Ascaris ssp. and dust mites, two important allergen sources in the tropics, will contribute in understanding their influence on asthma and atopy. The objective of this study was to investigate immunoglobulin E (IgE) cross-reactivity between Ascaris and two domestic mites in the tropics.

METHODS

Sera from 24 asthmatic patients were used in ELISA and immunoblotting IgE-binding inhibition assays using Ascaris, Blomia tropicalis and Dermatophagoides pteronyssinus extracts and the recombinants Blo t 10, ABA-1 and Blo t 13 as competitors. Identification of Ascaris allergens was confirmed by mass spectrometry (LC-MS/MS).

RESULTS

We detected at least 12 human IgE-binding components in Ascaris extract. Blomia tropicalis and D. pteronyssinus inhibited 83.3% and 79% of IgE-binding to Ascaris, while Ascaris inhibited 58.3% and 79.3% to B. tropicalis and D. pteronyssinus respectively. Mite tropomyosin inhibited 85% of IgE-binding to Ascaris. Affinity-purified human IgE to rBlo t 10 identified an allergen of 40 kDa in Ascaris extract, further confirmed as tropomyosin by LC-MS/MS. We found no evidence of IgE cross-reactivity between rABA-1 and any allergen component in mite extracts, including rBlo t 13.

CONCLUSIONS

There is cross-reactivity between Ascaris and mites, determined by several allergens including tropomyosin and glutathione-S-transferase. In addition to its potential impact on asthma pathogenesis, Ascaris infection and mite allergy diagnosis relying on the determination of specific IgE could be affected by this cross-reactivity. ABA-1 has no cross-reactive counterpart in mite extracts, suggesting its usefulness as a more specific marker of Ascaris infection.

Association between total immunoglobulin E and antibody responses to naturally acquired Ascaris lumbricoides infection and polymorphisms of immune system-related LIG4, TNFSF13B and IRS2 genes

The 13q33-34 region harbours a susceptibility locus to Ascaris lumbricoides, although the underlying genes are unknown. Immunoglobulin (Ig)E and IgG confer protective immunity and here we sought to investigate in an endemic population whether LIG4, TNFSF13B and IRS2 genes influence IgE and IgG levels against Ascaris and the ABA-1 allergen as a putative resistance marker. Mite-allergic asthmatic patients were analysed for potential relationships between Ascaris predisposition and allergy. One thousand and sixty-four subjects from Cartagena, Colombia, were included. Single nucleotide polymorphisms (SNPs) were genotyped using TaqMan assays. Antibody levels were measured by enzyme-linked immunosorbent assay. Linear and logistic regressions were used to model effects of genotypes on antibody levels. The GG genotype of LIG4 (rs1805388) was associated with higher IgE levels to Ascaris compared with other genotypes. TNFSF13B (rs10508198) was associated positively with IgG levels against Ascaris extract and IgE levels against ABA-1. In asthmatics, IRS2 (rs2289046) was associated with high total IgE levels. Associations held up after correction by population stratification using a set of 52 ancestry markers, age, sex and disease status. There was no association with asthma or mite sensitization. In a tropical population, LIG4 and TNFSF13B polymorphisms are associated with specific IgE and IgG to Ascaris, supporting previous linkage studies implicating the 13q33 region. Our results suggest that genes protecting against parasite infections can be different to those predisposing to asthma and atopy.

Association of G-protein-coupled receptor 154 with asthma and total IgE in a population of the Caribbean coast of Colombia

BACKGROUND

G protein-coupled receptor 154 was described as an asthma susceptibility gene by positional cloning. It has been subsequently associated with asthma and other inflammatory diseases in several populations with different ethnic origin. Replication of associations adds reliability to these findings.

OBJECTIVE

To analyze the association of G protein-coupled receptor 154 with asthma and total and mite-specific IgE levels in a population of the Caribbean Coast of Colombia.

METHODS

We genotyped seven single nucleotide proteins (SNPs) in GPR154 in 475 asthmatics, 394 controls and 116 families from Cartagena, Colombia using either SnaPshot or TaqMan. Total and specific IgE against Blomia tropicalis and Dermatophagoides pteronyssinus were determined by ELISA. Hardy-Weinberg equilibrium was assessed and case-control and family-based analyses were performed to evaluate the association between the SNPs and their haplotypes and asthma and IgE. Association analyses in the case-control dataset were corrected by population stratification using 52 ancestry informative markers.

RESULTS

Allelic distribution was similar to that described in other populations. Two SNPs were associated with the same direction of the effect in both datasets. Allele A of Hopo546333 was protective for asthma (case-control OR: 0.42; 95% CI: 0.17-0.99, P=0.042; P=0.043; families Z score=-2,236; P=0.025). Similarly, allele C of rs740347 conferred low risk for asthma (OR: 0.44; 95% CI: 0.28-0.70, P=0.00017; Pc=0.00037) and total IgE (OR: 0.29; 95% CI: 0.09-0.88, P=0.015; Pc=0.030) in the case-control study and families (Z score=-3.207, P=0.0013; Z score=-3.182, P=0.0014, respectively). Haplotype CCAGGT was associated with total IgE (OR: 1.76; 95% CI: 1.14-2.71, P=0.006, Pc=0.007) in the case-controls group and CGCGGT with both phenotypes (P=0.044 and P=0.032, respectively) in families. Neither SNPs nor haplotypes were associated with levels of mite-specific IgE.

CONCLUSIONS

Our findings in a sample of asthmatics from Colombia suggest a relevant role of G protein-coupled receptor 154 in the pathogenesis of asthma and allergy.

The A-444C polymorphism in the leukotriene C4 synthase gene is associated with aspirin-induced urticaria

BACKGROUND

Cysteinyl leukotriene production seems to be dysregulated in patients with hypersensitivity to aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs). However, the underlying pathogenic mechanisms of these reactions are poorly understood. Previous studies have suggested a role for the A-444C polymorphism on the leukotriene C4 synthase gene (LTC4S) in aspirin-induced urticaria (AIU), but the results are controversial.

OBJECTIVE

To evaluate in a case-control study whether the A-444C polymorphism in the promoter region of LTC4S is associated with AIU and atopic phenotypes in a Venezuelan population.

METHODS

One hundred ten patients with AIU and 165 nonallergic controls were included. AIU was diagnosed by clinical history and confirmed by double-blind placebo-controlled oral provocation tests with NSAIDs. Genotyping of A-444C was performed by real-time polymerase chain reaction using Taqman probes. Atopy was defined as a positive skin test result to any of the 25 aeroallergens tested. Total and mite-specific immunoglobulin (Ig) E levels in serum were quantified using an enzyme-linked immunosorbent assay

RESULTS

A-444C was associated with AIU. The C allele was more frequent in patients with the cutaneous pattern of AIU and in patients with low skin reactivity to histamine. There was no association between A-444C and asthma, atopy, or total IgE levels.

CONCLUSION

The C allele of the A-444C polymorphism is a risk factor for AIU in our population and could be a genetic marker for this phenotype. Furthermore, this single-nucleotide polymorphism is mainly associated with the cutaneous clinical pattern and with low skin response to histamine.

Detection and characterization of waterborne gastroenteritis viruses in urban sewage and sewage-polluted river waters in Caracas, Venezuela

The detection and molecular characterization of pathogenic human viruses in urban sewage have been used extensively to derive information on circulating viruses in given populations throughout the world. In this study, a similar approach was applied to provide an overview of the epidemiology of waterborne gastroenteritis viruses circulating in urban areas of Caracas, the capital city of Venezuela in South America. Dry season sampling was conducted in sewers and in a major river severely polluted with urban sewage discharges. Nested PCR was used for detection of human adenoviruses (HAds), while reverse transcription plus nested or seminested PCR was used for detection of enteroviruses (HuEVs), rotaviruses (HRVs), noroviruses (HuNoVs), and astroviruses (HAstVs). HRVs were fully characterized with genotype-specific primers for VP4 (genotype P), VP7 (genotype G), and the rotavirus nonstructural protein 4 (NSP4). HuNoVs and HAstVs were characterized by sequencing and phylogenetic analysis. The detection rates of all viruses were >or=50%, and all sampling events were positive for at least one of the pathogenic viruses studied. The predominant HRV types found were G1, P[8], P[4], and NSP4A and -B. Genogroup II of HuNoVs and HAstV type 8 were frequently detected in sewage and sewage-polluted river waters. This study reveals relevant epidemiological data on the distribution and persistence of human pathogenic viruses in sewage-polluted waters and addresses the potential health risks associated with transmission of these viruses through water-related environmental routes.

Immunological characterization of a Blo t 12 isoallergen: identification of immunoglobulin E epitopes

BACKGROUND

Differences in the IgE response to isoallergens could have clinical implications; therefore, its analysis will contribute to the design of better strategies for the diagnosis and treatment of allergic respiratory diseases. Several isoforms have been described from mites but there is no information about the clinical impact of Blomia tropicalis isoallergens.

OBJECTIVE

To evaluate the differences in the IgE response against two Blo t 12 isoallergens.

METHODS

The IgE-binding properties of Blo t 12 isoallergens were analysed by ELISA, a skin prick test and ELISA cross-inhibition. Epitope mapping was performed using synthetic overlapping peptides. Fold recognition methods were used to model the chitin-binding domain of the two isoallergens.

RESULTS

The frequency and strength of the IgE response were greater for Blo t 12.0101 than for Blo t 12.0102. Three IgE-binding areas were identified in Blo t 12.0101; one of them included two residues that are different in Blo t 12.0102. Modelling of the chitin-binding domains of these allergens predicted that they have structural differences that could influence antibody recognition of one of these epitopes.

CONCLUSION

In silico structural analysis and immunological characterization of Blo t 12 reveals that allergen polymorphism influences IgE reactivity. Blo t 12.0101 is the most IgE-reactive isoform in Cartagena. The identified IgE epitopes could be mutated to obtain hypoallergenic molecules of potential use for immunotherapy.

A NOS1 gene polymorphism associated with asthma and specific immunoglobulin E response to mite allergens in a Colombian population

BACKGROUND

Nitric oxide (NO) is involved in asthma pathogenesis and is synthesized by three isoforms of NO synthase, one of them encoded by NOS1 gene. The CA-repeat and the C5266T SNP in NOS1 exon 29 have been associated with asthma and IgE levels. We thought to test the association of asthma and asthma-related phenotypes with the exon 29 CA-repeat and the C5266T SNP in a Colombian population sample.

METHODS

The CA-repeat and the C5266T SNP were genotyped in 167 asthmatics and 166 controls using PCR-based fragment length polymorphism and TaqMan assay. We also determined total and mite-specific IgE against Blomia tropicalis and Dermatophagoides pteronyssinus.

RESULTS

Three new CA-repeat alleles, 14, 23 and 24 repeats were detected. Allele comprising 16 repeats was associated with asthma (OR: 1.90 (CI 1.22-2.97, p(c) = 0.028) and low total (p(c) = 0.02) and specific IgE to B. tropicalis (p(c) < 0.0001) and D. pteronyssinus (p(c) < 0.0001). We found no association of the C5266T SNP and asthma or IgE levels.

CONCLUSION

NOS1 exon 29 CA-repeat may be a risk factor for asthma susceptibility and mite specific IgE response in a Colombian population.

Allergenic composition of the mite Suidasia medanensis and cross-reactivity with Blomia tropicalis

BACKGROUND

Mites of the genus Suidasia are commonly found in house dust and may play an allergenic role in exposed populations. However, the allergenic potential and clinical impact of this genus has not been well established. The main objective of this project was to evaluate the allergenic role of the mite Suidasia medanensis.

METHODS

An extract of S. medanensis was prepared and the allergen composition determined by immunoblot. Specific IgE antibody levels to S. medanensis and Blomia tropicalis were evaluated by radioallergosorbent (RAST) in the sera of 97 allergic asthmatic patients and 50 nonallergic subjects. Cross-reactivity between S. medanensis and the mite species B. tropicalis and Dermatophagoides farinae was investigated by RAST and immunoblot inhibitions.

RESULTS

Seventy-one asthmatic patients sera (73.2%) had positive IgE reactivity to S. medanensis; 14 allergens with molecular weights ranging from 7.5 to 105 kDa were detected. The most frequently detected had molecular weights of 30-31 (54.8%), 24.5 (42%), 21 (38.7%), 47 (35%) and 58 kDa (35.5%). Blomia tropicalis extract inhibited IgE binding to nine of these identified allergens. Four B. tropicalis allergens were inhibited by S. medanensis extract. RAST inhibition results demonstrated a high degree of inhibition by B. tropicalis (87.2%) and D. farinae (90.9%) than by S. medanensis (32%).

CONCLUSIONS

Sensitization to S. medanensis is common in asthmatic allergy patients in Cartagena. An important degree of cross-reactivity was established between S. medanensis and B. tropicalis, and D. farinae.

A novel promoter polymorphism in the gene encoding complement component 5 receptor 1 on chromosome 19q13.3 is not associated with asthma and atopy in three independent populations

BACKGROUND

The inflammatory functions of complement component 5 (C5) are mediated by its receptor, C5R1, which is expressed on bronchial, epithelial, vascular endothelial and smooth muscle cells. A susceptibility locus for murine allergen-induced airway hyper-responsiveness was identified in a region syntenic to human chromosome 19q13, where linkage to asthma has been demonstrated and where the gene encoding C5R1 is localized.

OBJECTIVE

The aim of this study was to screen for novel polymorphisms in the C5R1 gene and to determine whether any identified polymorphisms are associated with asthma and/or atopy and whether they are functional.

METHODS

Single-nucleotide polymorphism (SNP) detection in the gene encoding C5R1 was performed by direct sequencing. Genotyping was performed in three populations characterized for asthma and/or atopy: (1) 823 German children from The Multicenter Allergy Study; (2) 146 individuals from Tangier Island, Virginia, a Caucasian isolate; and (3) asthma case-parent trios selected from 134 families (N=783) in Barbados. Functional studies were performed to evaluate differences between the wild-type and the variant alleles.

RESULTS

We identified a novel SNP in the promoter region of C5R1 at position -245 (T/C). Frequency of the -245C allele was similar in the German (31.5%) and Tangier Island (36.3%) populations, but higher in the Afro-Caribbean population (53.0%; P=0.0039 to <0.0001). We observed no significant associations between the -245 polymorphism and asthma or atopy phenotypes. Upon examination of the functional consequences of the -245T/C polymorphism, we did not observe any change in promoter activity.

CONCLUSION

This new marker may provide a valuable tool to assess the risk for C5a-associated disorders, but it does not appear to be associated with asthma and/or atopy.

Importance of including Blomia tropicalis in the routine diagnosis of Venezuelan patients with persistent allergic symptoms

BACKGROUND

Blomia tropicalis is a common mite found in the house dust of many tropical countries including Venezuela. The prevalence of skin test and specific serum immunoglobulin (Ig)E reactivity to B. tropicalis in Venezuela has not been previously evaluated.

METHODS

In the present study we evaluated the skin reactivity by skin prick test and specific IgE by a multiple antigen blot assay, against B. tropicalis and Dermatophagoides pteronyssinus, in a group of 115 subjects who attended the Allergy Clinic of the Institute of Biomedicine, Caracas, Venezuela, and we studied possible cross reactions between similar proteins of these two mites.

RESULTS

One hundred and six patients with persistent allergic respiratory symptoms showed a positive skin prick test to at least one of the mite extracts, with the frequency of positive reactions to B. tropicalis being as high as to D. pteronyssinus. Twelve patients reacted only to D. pteronyssinus and 13 different patients only to B. tropicalis. Specific IgE to each of the mite extracts was found with similar frequency, and the results coincided with the skin test reactivity.

CONCLUSIONS

The study indicated the importance of including B. tropicalis in routine diagnostic testing in tropical and sub-tropical situations.

Life-cycle of Suidasia medanensis (=pontifica) (Acari: Suidasiidae) under laboratory conditions in a tropical environment

The life cycle of Suidasia medanensis (=pontifica) was studied under laboratory conditions at 26 degrees C and 86% relative humidity. Freshly laid eggs were observed until they developed into adults and the periods between stages were recorded. Production of eggs by mated females was monitored until they died. The eggs required an average of 12.6 +/- 0.6 days to develop into adults. Mean longevity of mated females and males was similar (48.6 +/- 13 and 49.1 +/- 20 days, respectively). The conditions used in this study may be considered optimal for in vitro culture of S. medanensis.

Atopic dermatitis is associated with a functional mutation in the promoter of the C-C chemokine RANTES

Up-regulation of C-C chemokine expression characterizes allergic inflammation and atopic diseases. A functional mutation in the proximal promoter of the RANTES gene has been identified, which results in a new consensus binding site for the GATA transcription factor family. A higher frequency of this allele was observed in individuals of African descent compared with Caucasian subjects (p < 0.00001). The mutant allele was associated with atopic dermatitis in children of the German Multicenter Allergy Study (MAS-90; p < 0.037), but not with asthma. Transient transfections of the human mast cell line HMC-1 and the T cell line Jurkat with reporter vectors driven by either the mutant or wild-type RANTES promoter showed an up to 8-fold higher constitutive transcriptional activity of the mutant promoter. This is the first report to our knowledge of a functional mutation in a chemokine gene promoter. Our findings suggest that the mutation contributes to the development of atopic dermatitis. Its potential role in other inflammatory and infectious disorders, particularly among individuals of African ancestry, remains to be determined.

Determination of Duffy genotypes in three populations of African descent using PCR and sequence-specific oligonucleotides

The expression of the Duffy Antigen/Receptor for Chemokines (DARC) on red blood cells (RBC) has been commonly determined using hemagglutination tests. Because the vast majority of African individuals are Duffy-negative, screening for DARC expression on RBC is a valuable tool to assess Caucasian admixture in populations of African descent. Furthermore, blood group antigens have been frequently tested as potential risk factors for complex diseases. We established a dot-blotting protocol using sequence-specific oligonucleotides (SSOs) for the DARC-46T ("Duffy-positive") and -46C ("Duffy-negative") alleles. With this method, but not with serological methods, Duffy-positive individuals can be further characterized as homozygous or heterozygous for the dominant Duffy-positive allele, allowing more precise estimation of allele frequencies and admixture in heterogeneous populations. In unrelated African American (n = 235), Afro-Caribbean (n = 90) and Colombian (n = 93) subjects, the frequency of the -46T allele was 21.7%, 12.2% and 74.7%, respectively. The percentage of Duffy-positive individuals (homozygous or heterozygous for the -46T allele) in each population was in accordance with published frequencies. As expected, the -46C allele was not detected in 20 Caucasian subjects. This sensitive and specific method allows for the rapid and inexpensive screening of large samples for Duffy genotypes using small quantities of genomic DNA.

Structural and ligand binding analysis of recombinant blo t 13 allergen from Blomia tropicalis mite, a fatty acid binding protein

BACKGROUND

We have previously described a cDNA (clone Bt6) encoding a novel allergen from Blomia tropicalis, which showed sequence similarities to the FABP/P2/cellular retinoic acid binding protein/cellular retinol binding protein, a family of cytosolic lipid transport proteins (cLTPs). This work was planned to better characterize this allergen to which the official name Blo t 13 had been assigned.

METHODS

Fluorescence-based lipid ligand binding assays and secondary structure analysis by circular dicroism were carry out using recombinant Blo t 13 (rBlo t 13) protein. Structural predictions and molecular modelling were performed based on the amino acid sequence inferred from the open reading frame of Bt6 cDNA sequence.

RESULTS

rBlot t 13 binds the natural fluorescent fatty acid cis-parinaric acid and oleic acid by competition, but not retinol, retinoic acid, cholesterol, dansylated or anthroxylated fatty acids such as dansyl-DL-aminocaprylic acid and 12-(9-anthroyloxy)-stereate. Circular dichroism analysis indicated that rBlo t 13 comprises 45% beta-sheet and 13% alpha-helix. The amino acid sequence of Blo t 13 modelled well to known crystal structures of cLTPs providing a tertiary structural model comprising ten beta-strands organized into two beta-sheets, and two short alpha-helices.

CONCLUSION

Blo t 13 is a fatty acid-specific member of the beta-rich cLTP family of proteins.

HLA-B27 subtypes in patients with ankylosing spondylitis (As) in Colombia

OBJECTIVE

We investigated the distribution of HLA-B27 subtypes in patients with ankylosing spondylitis (AS) belonging to two ethnic groups of Colombia.

MATERIAL AND METHODS

PCR-SSOs was used to detect the polymorphism in exons 2 and 3 of HLA-B27 in two groups of patients: 39 Mulattos and 20 Mestizos. Fifty-nine of them suffered of ankylosing spondylitis (AS), including two patients with ankylosing spondylitis plus anterior uveitis (AU). Only two out of eight HLA-B27 subtypes studied (B*2701-B*2708) were found.

RESULTS

The distribution of these alleles in the whole population was: B*2705: 87.1% and B*2702: 12.8% in the Mulattos group; 80% were B*2705 and 20% B*2702 in Mestizos group. The distribution of HLA-B27 subtypes was: 84.74% of patients with AS were B*2705 and 15.26% B*2702.

CONCLUSIONS

There was no significant difference in the distribution of HLA-B27 subtypes among the patients ethnic groups studied. Other authors have shown that B*2705, B*2702 and B*2704, the more frequent subtypes, are equally associated to the disease. Although population studies need to be done to analyze the distribution of subtypes between patients and controls, the low frequency of HLA-B27 within the normal population does not permit to do a representative number of controls; our results suggest that HLA-B*2705 and HLA-B*2702 are the subtypes more frequently associated with AS in patients from the two more prevalent patients ethnic groups in Colombia.

Analysis of the cross-reactivity between BtM and Der p 5, two group 5 recombinant allergens from Blomia tropicalis and Dermatophagoides pteronyssinus

BACKGROUND

In tropical climates, sensitization to Bloma tropicalis and Dermatophagoides pteronyssinus is high and mainly directed to species-specific allergens. There is some cross-reactivity between extracts of these mites, probably due to the group 5 allergens that have high sequence homology.

OBJECTIVE AND METHODS

We used the radioallergosorbent test (RAST), RAST inhibition and immunoblotting inhibition experiments to investigate the cross-reactivity between the recombinant allergens BtM and Der p 5, expressed as glutathione S-transferase fusion proteins, to detect the epitopes involved and to analyze the importance of this cross-reactivity.

RESULTS

Seventy-nine percent of 48 patients sera were RAST positive to both recombinants, with a strong correlation (r = 0.8, p<0.0001). BtM inhibited 25 and 21.1% of IgE-binding to B. tropicalis and D. pteronyssinus extracts respectively and Der p 5 inhibited 22 and 24% of IgE-binding to D. pteronyssinus and B. tropicalis extracts. Furthermore, BtM inhibited 74.5% of IgE binding to Der p 5 and Der p 5 inhibited 72.4% of IgE-binding to BtM. RAST inhibition with BtM-derived synthetic peptides showed that peptide 4 (residues 35-50) and peptide 5 (residues 46-61) inhibited 37 and 16% of IgE-binding to BtM while peptides 5 and 2 (residues 14-30) were able to inhibit the IgE binding (32 and 28%, respectively) to Der p 5.

CONCLUSION

There is cross-reactivity between BtM and Der p 5, which explains almost all the cross-reactivity between the two mite extracts. This cross-reactivity seems to be related to epitope(s) at the C-terminal segment of these allergens.

Sensitization to mite allergens and acute asthma in a tropical environment

The objective of this study was to determine whether sensitization to certain aeroallergens is associated with acute asthma in Cartagena, Colombia. Ninety-nine subjects with acute asthma and 100 controls evaluated for other reasons were studied at a local emergency room. Sensitization was established by specific IgE determinations. Statistically significant differences between asthmatic subjects and controls were found in the prevalence of specific IgE to Dermatophagoides pteronyssinus, 64.6% vs. 28% (p = 0.0001); to Dermatophagoides farinae, 74.7% vs. 40% (p = 0.0001); to Euroglyphus maynei, 68.7% vs. 22% (p = 0.0001); and to Blomia tropicalis, 54.5% vs. 17% (p = 0.0001). The odds ratios were 4.9; 4.4; 7.7 and 5.8, respectively. In contrast, there was no significant difference between subjects with asthma and controls in the prevalence of specific IgE to Alternaria tenuis: 4% vs. 1% (p = 0.35); to Paspalum notatum (Bahia grass): 28% vs. 19% (p = 0.16); to Periplaneta americana (American cockroach): 21% vs. 19% (p = 0.83); to Ambrosia artemisifolia (short ragweed): 12% vs. 23% (p = 0.11); and to cat epithelium: 5% vs. 1% (p = 0.17). The results suggest that sensitization to domestic mites in subjects who reside in this tropical city is associated with acute asthma that requires emergency room treatment.

Asthma mortality in Columbia

BACKGROUND

Asthma mortality rates have increased in several industrialized countries during the past two decades. In Latin America, there have been reported only a few national studies of asthma mortality.

OBJECTIVE

To determine asthma mortality rates in Colombia from 1979 to 1994.

METHODS

Death certificates from the National Administrative Statistical Department of Colombia were collected and analyzed.

RESULTS

For the entire population we found increasing rates of asthma mortality from 2.15 in 1979 to 3.3 in 1985 followed by a decrease to 1.6 in 1994. Overall, the trend has been to decrease, with a variation coefficient of 1.09% by year. Age-adjusted rates of death from asthma, based on the population distribution of 1973, showed the same decreasing trend. Deaths from asthma were more frequent in subjects older than 35 years as compared with those younger than 5 years of age or the age group ranging from 5 to 34 years. For the latter, rates of death increased from 0.32 in 1980 to 0.37 in 1988, and fell to 0.20 in 1991. From 1992 to 1994 rates for 5 to 34 years of age were higher than previously, increasing to 0.9 in 1992 and decreasing to 0.6 in 1994. There was no significant variation in death rates between men and women. Sixty-two percent of deaths from asthma occurred at home, 31% at hospitals, and 6.7% in other places. Most asthma deaths were in urban areas.

CONCLUSIONS

In contrast to that observed in industrialized countries, we found a decreasing trend in asthma mortality in Colombia. Rates of death from asthma, however, are still high in this country.

Asthma mortality in Latin America

There are not enough data concerning asthma mortality in Latin America. The Latin American Society of Allergy and Immunology coordinated this project to provide reliable data for gaining knowledge about our present situation, which is a condition indispensable to changing it. The following countries participated in this study: Argentina, Brazil, Chile, Colombia, Costa Rica, Cuba, Mexico, Paraguay, Peru, Uruguay and Venezuela. A uniform protocol was designed in Santa Fe, Argentina. Asthma mortality rates were analyzed in accordance with two variables: age-adjusted rates (5-34) and total death rates. The total population studied was 107, 122, 529 inhabitants. The highest death rates were found in Uruguay and Mexico (5.63), and the lowest in Paraguay (0.8) and Colombia (1.35). Age-adjusted (5-34) rates were higher in Costa Rica (1.38) and lower in Chile (0.28). Regarding sex, the analysis of the information provided by seven countries showed a predominance of females (51.8%) over males (48.18%). In the southern Latin American countries such as Chile, Uruguay, Paraguay and Argentina, which have marked climatic differences, deaths occurred mainly in the winter. It is important to emphasize that, in most countries, deaths from asthma occurred at home: Chile (60.7%), Argentina (63.4%) and Paraguay (88%). However, in Uruguay, 58.6% occurred during hospitalization. Mortality rates from bronchial asthma are high in most of the Latin American countries studied, even though further studies are needed. Asthma is a serious global health problem. People of all ages in countries throughout the world are affected by this chronic airway disorder that can be severe and sometimes fatal. The health ministries of each country do not believe asthma is a significant issue. Therefore, we should provide them with sound epidemiological studies to convince them to change their attitude toward this disease.

Cloning and IgE binding of a recombinant allergen from the mite Blomia tropicalis, homologous with fatty acid-binding proteins

To characterize the allergens of Blomia tropicalis, a cDNA library was constructed and screened with allergic sera from asthmatic patients. One clone, Bt6, was subcloned and sequenced. The nucleotide sequence of 934 bp length shows a 390-bp reading frame which encodes a 130-amino acid protein with a MW 14.8 kD. No potential glycosylation site was found in the predicted protein. The inferred amino acid sequence has no homology to known allergens. It has a cytosolic fatty acid-binding protein (FABP) signature at 5-22 amino acid residues, 42.3% identity with the Sm14-FABP of Schistosoma mansoni and 36% identity with FABPs from rat, mouse, bovine and human. The protein was expressed as a GST fusion protein and the purified GST-Bt6 used for dot blot, RAST and RAST inhibition assays. The frequency of IgE binding of allergic sera to Bt6 was low (11%) and usually weak. One positive serum did, however, show strong reactivity by RAST and dot blot and Bt6 could inhibit 60% of the IgE binding of this serum to the B. tropicalis extract. These data show that Bt6 encodes a mite FABP with allergenic properties, which are pronounced in some atopic subjects.

Nucleotide sequence analysis of a complementary DNA coding for a Blomia tropicalis allergen

Blomia tropicalis is a mite of allergenic importance in tropical and subtropical areas. A clone (Bt11a) from a B. tropicalis complementary DNA library was expressed in lambda phage and analyzed by plaque radioimmunoassay. The recombinant allergen produced by this clone was bound by IgE in 16 of 32 sera from individuals with asthma with a positive RAST response and none of 3 control sera from healthy individuals with negative RAST response to B. tropicalis. The cDNA insert was amplified by polymerase chain reaction with use of universal primers. A 582-base-pair (bp) fragment was cloned into a pCR II vector. The complete sequence of both strands was determined by using T7, SP6, and internal primers. The sequence shows a 432 bp reading frame with a 34 bp 5' untranslated region and a 116 bp 3' untranslated region with a poly A tail. Analysis of the sequence suggests that it encodes a putative signal peptide of 20 residues and a 124-residue mature protein allergen of 14,206 Da. The nucleotide and the inferred amino acid sequences did not show homology to any known sequence. No potential N-linked glycosylation site was found. The recombinant protein appears to represent a major allergen of the mite B. tropicalis.

Cloning and expression of complementary DNA coding for an allergen with common antibody-binding specificities with three allergens of the house dust mite Blomia tropicalis

The mite Blomia tropicalis is a potent source of allergens in tropical and subtropical regions. So far, most of these allergens have only been studied by immunoblotting. To characterize them at the molecular level, a lambda gt11 complementary DNA library was constructed from messenger RNA isolated from whole B. tropicalis mites. This library was screened by using pooled sera from patients allergic to B. tropicalis in a plaque IgE radioimmunoassay. A B. tropicalis IgE-positive clone (Bt-M) was selected for immunologic studies. After subcloning into pBluescript (Stratagene, La Jolla, Calif.), it produced a sequence of 310 bp, with a probable amino acid sequence of 72 residues for the expressed peptide. The recombinant protein was transferred to nitrocellulose filters and probed with 100 sera from patients allergic to B. tropicalis. Forty-seven percent of sera reacted with the recombinant allergen. Immunoblottings performed with allergic serum and B. tropicalis-affinity-purified IgE demonstrated that the recombinant protein shares allergenic epitopes with the 11-13, 14, and 16 kd native allergens of B. tropicalis, which are known to be important allergens of this mite.

Sequential determinations of Dermatophagoides spp. allergens in a tropical city

The purpose of this study was to establish seasonal levels of Der p 1, Der f 1 and D. pteronyssinus allergens in mattress and floor dust samples in the homes of 20 mite-allergic asthmatic patients in Cartagena, Colombia. Dust samples were collected using a portable vacuum cleaner once monthly for the same 12 months in all houses. The highest Der p 1 levels in mattress samples were detected in August (geometric mean = 109.49 ng/g) and represented a 2.2-times increase from the lowest level observed in November. Der f 1 was detected in only 3 mattresses, ranging from 90 ng to 1.6 micrograms per gram of dust. The highest levels were detected in February and March. The highest level of D. pteronyssinus allergens in mattress dust samples, quantitated by RAST-inhibition, was 8, 994 AU/g (80% inhibition); the lowest level detected was 150 AU/g (5% inhibition). Allergen levels were significantly higher in mattresses than in floor samples (p < 0.001). Overall, a Spearman rank correlation coefficient of 0.48, p < 0.001, was obtained between Der p 1 and D. pteronyssinus allergens. There was a good correlation between mite allergens and absolute humidity (r = 0.8, p = 0.007). Der p 1, Der f 1 and D. pteronyssinus allergen levels show minimal variations in this tropical environment. Allergens derived from various mite species must be considered when assessing mite allergen exposure in these environments.

Parent, teacher, and peer ratings of physically abused and nonmaltreated children's behavior

Behavior ratings by parents, teachers, and classmates of physically abused fourth to sixth graders, identified from the New York City Maltreatment Register, and case-matched classroom controls, showed substantial concurrence among informants: Parents and teachers both rated significantly more behavioral disturbance in the abused children, and peers' ratings were significantly correlated with adults' ratings, especially those by teachers. Children's exposure to spouse or partner physical abuse, which had a substantial prevalence among both child-abusing and control families, reduced the difference in disturbance ratings between children who were themselves physically abused and those who were not. Overall, we conclude that physically abused children show pervasive behavioral disturbance, in that parents, teachers, and classmates all see higher levels of behavior problems and lower levels of socially desirable behavior in them compared to their nonmaltreated peers.

Identification of allergens from the mite Blomia tropicalis

In some tropical areas the mite Blomia tropicalis is a clinically important allergenic component of house dust, inducing specific IgE immune response in patients with allergic respiratory diseases such as asthma and rhinitis. The identification of allergens of this mite is necessary to obtain appropriate reagents for diagnostic and treatment procedures. We carried out this study using immunoblotting to detect the allergens of B. tropicalis. Our results demonstrate that this mite has one major allergen (11-13 kDa) and three other important allergens with about 50% binding (64, 36 and 33 kDa). Therefore, B. tropicalis should be regarded as an important source of allergens in the house dust in tropical areas, besides those derived from other mites.