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.

BACKGROUND:Saliva and muscle-derived mosquito allergens have been purified and characterized. However, the complete set of allergens remains to be elucidated. In this study, we identified and characterized IgE-binding proteins from the mosquito species Aedes aegypti.METHODS:Serum was obtained from 15 allergic individuals with asthma and/or rhinitis and sensitized to mosquito. IgE binding was determined by ELISA. Total proteins from freeze-dried bodies of A. aegypti were extracted and IgE-reactive proteins were identified by 2D gel electrophoresis, followed by Western blot with pooled or individual sera. IgE-reactive spots were further characterized by mass spectrometry.RESULTS:Twenty-five IgE-reactive spots were identified, corresponding to 10 different proteins, some of which appeared as different variants or isoforms. Heat-shock cognate 70 (HSC-70) and tropomyosin showed IgE reactivity with 60% of the sera, lysosomal aspartic protease, and "AAEL006070-PA" (Uniprot: Q177P3) with 40% and the other proteins with <33.3% of the sera. Different variants or isoforms of tropomyosin, arginine or creatine kinase, glyceraldehyde-3-phosphate dehydrogenase (GPDH), calcium-binding protein, and phosphoglycerate mutase were also identified. The mixture of three allergens (Aed a 6, Aed a 8, and Aed a 10) seems to identify more than 80% of A. aegypti-sensitized individuals, indicating that these allergens should be considered when designing of improved mosquito allergy diagnostic tools.CONCLUSIONS:The newly identified allergens may play a role in the pathophysiology of mosquito allergy in the tropics, and some of them might be important arthropod-related proteins involved in cross-reactivity between A. aegypti and other allergenic arthropods.

RationaleAllergy to mite is very common in tropical and subtropical regions of the world, where shrimp allergy is also an important problem. We hypothesized that allergens belonging to the Fatty Acid Binding Protein family such as group 13 of mite allergen and its homologues might contribute to the cross-reactivity between mites and shrimps. To explore this topic we begin for analyzing the levels of specific IgE mites, shrimp and Blot 13 in sera from an allergic population.MethodsOne hundred sixty five sera from mite allergic patients living on the Island of Martinique, were selected for specific IgE determination by ELISA to B. tropicalis, D. pteronyssinus, the pacific white shrimp (Litopenaeus vannamei) extracts and to recombinant Blo t 13.0101 from B. tropicalis as representative of group 13 mite allergen.ResultsThe presence of IgE to B. tropicalis and D. pteronyssinuswas observed in all the sera analyzed, eighty six of which (52.12%) had positive IgE levels to shrimp extract and forty nine (29.51%) had positive levels to Blo t 13.0101. thirty two of the 49 sera sera with positive IgE levels to Blot 13, had also positive IgE levels to mite and L. vannamei extracts.ConclusionsA high frequency of co-sensitization to mite and shrimp was observed in a group of allergy patients from the Caribbean. The role of Blo t 13 as a cross-reactive allergen between these two allergen sources deserves further evaluation. Founded by University of Cartagena and Colciencias, Colombia. RationaleAllergy to mite is very common in tropical and subtropical regions of the world, where shrimp allergy is also an important problem. We hypothesized that allergens belonging to the Fatty Acid Binding Protein family such as group 13 of mite allergen and its homologues might contribute to the cross-reactivity between mites and shrimps. To explore this topic we begin for analyzing the levels of specific IgE mites, shrimp and Blot 13 in sera from an allergic population. Allergy to mite is very common in tropical and subtropical regions of the world, where shrimp allergy is also an important problem. We hypothesized that allergens belonging to the Fatty Acid Binding Protein family such as group 13 of mite allergen and its homologues might contribute to the cross-reactivity between mites and shrimps. To explore this topic we begin for analyzing the levels of specific IgE mites, shrimp and Blot 13 in sera from an allergic population. MethodsOne hundred sixty five sera from mite allergic patients living on the Island of Martinique, were selected for specific IgE determination by ELISA to B. tropicalis, D. pteronyssinus, the pacific white shrimp (Litopenaeus vannamei) extracts and to recombinant Blo t 13.0101 from B. tropicalis as representative of group 13 mite allergen. One hundred sixty five sera from mite allergic patients living on the Island of Martinique, were selected for specific IgE determination by ELISA to B. tropicalis, D. pteronyssinus, the pacific white shrimp (Litopenaeus vannamei) extracts and to recombinant Blo t 13.0101 from B. tropicalis as representative of group 13 mite allergen. ResultsThe presence of IgE to B. tropicalis and D. pteronyssinuswas observed in all the sera analyzed, eighty six of which (52.12%) had positive IgE levels to shrimp extract and forty nine (29.51%) had positive levels to Blo t 13.0101. thirty two of the 49 sera sera with positive IgE levels to Blot 13, had also positive IgE levels to mite and L. vannamei extracts. The presence of IgE to B. tropicalis and D. pteronyssinus was observed in all the sera analyzed, eighty six of which (52.12%) had positive IgE levels to shrimp extract and forty nine (29.51%) had positive levels to Blo t 13.0101. thirty two of the 49 sera sera with positive IgE levels to Blot 13, had also positive IgE levels to mite and L. vannamei extracts. ConclusionsA high frequency of co-sensitization to mite and shrimp was observed in a group of allergy patients from the Caribbean. The role of Blo t 13 as a cross-reactive allergen between these two allergen sources deserves further evaluation. Founded by University of Cartagena and Colciencias, Colombia. A high frequency of co-sensitization to mite and shrimp was observed in a group of allergy patients from the Caribbean. The role of Blo t 13 as a cross-reactive allergen between these two allergen sources deserves further evaluation. Founded by University of Cartagena and Colciencias, Colombia.

RATIONALE: Fatty Acid Binding Protein family (FABP) has conserved molecular structure and biological function, which suggests cross-reactivity among their members such as group 13 mite allergens and human FABP. METHODS: ELISA was performed with the recombinant allergens Blo t 13, Der f 13 (isoforms DF414 and DF 1096) and the human FABP from heart (H-FABP), brain (B-FABP) and adipocyte (A-FABP) using sera from asthmatic allergy patients and the monoclonal antibodies anti-Blo t 13 (5G3) and anti H-FABP (67D3 and 66E2). ELISA cross-inhibitions were done using sera from asthmatic patients. RESULTS: IgE reactivity to H-FABP, B-FABP and A-FABP was detected in two of twelve sera from asthmatic allergic patients sensitized to Blo t 13. The IgE reactivity to Blo t 13 in solid phase was inhibited 32.6% by pre-adsorption with H-FABP, and 33.84% with B-FABP. The inhibition of IgE binding to B-FABP by Blo t 13 was 85.61%. The maximum inhibition of IgE binding to Blo t 13 in solid phase by DF414 was 44.6%; when DF414 was in solid phase the maximum inhibition produced by Blo t 13 was 79.4%. The monoclonal 5G3 reacted with DF414 and DF1096 but not with human FABPs. The monoclonal 67D3 reacted strongly against DF1096. CONCLUSIONS: IgE antibody reactivity against the human FABPs was detected in sera from asthmatic allergic patients, which seems to be induced by exposure to Blo t 13. DF414 and Blo t 13 showed a moderate cross-reactivity. The clinical significance of these findings is unknown.

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.

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.

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.