Bovine Dander Research Articles

Characterization of Relevant Bovine Dander Allergen Components.

Diagnostic tests in occupational allergic diseases are highly dependent on the quality of available allergen extracts and specific IgE tests. To enhance diagnostic testing in cattle-related occupational rhinitis, asthma, and urticaria, we produced an in- house cow dander extract, assessed its allergen profile and performance in clinical tests, and compared it with commercial bovine dander extracts. One hundred patients with a suspected cattle-related occupational disease underwent skin prick tests (SPTs) with in-house and 1 or 2 commercial bovine dander extracts. Nasal allergen provocation tests were performed on 31 patients with suspected occupational rhinitis. We used Western blot to study the specific IgE-protein reactions from the sera of the patients with positive provocation test results and identified allergens from immunoblot bands using tandem mass spectrometry. The odorant-binding protein Bos d OBP, bovine serum albumin (Bos d 6), and the lipocalin (Bos d 2) were identified as the major allergens. We found a total of 24 bovine dander allergens, of which several were formerly unknown. The sensitivity and specificity of the in-house extract in SPTs were 100% and 94%, respectively, in 87 patients. The SPT results were negative in 20 healthy controls. Nasal allergen provocation tests with in-house extract detected occupational rhinitis with 100% sensitivity in 21 patients. The provocation results remained negative in 5 healthy controls. Three major and several minor allergens in bovine dander caused occupational rhinitis. Diagnosis of bovine allergen-related occupational diseases requires a sufficient concentration and variety of tested allergens.

Dimerization of lipocalin allergens.

Lipocalins are one of the most important groups of inhalant animal allergens. The analysis of structural features of these proteins is important to get insights into their allergenicity. We have determined two different dimeric crystal structures for bovine dander lipocalin Bos d 2, which was earlier described as a monomeric allergen. The crystal structure analysis of all other determined lipocalin allergens also revealed oligomeric structures which broadly utilize inherent structural features of the β-sheet in dimer formation. According to the moderate size of monomer-monomer interfaces, most of these dimers would be transient in solution. Native mass spectrometry was employed to characterize quantitatively transient dimerization of two lipocalin allergens, Bos d 2 and Bos d 5, in solution.

Effect of farming environment on sensitisation to allergens continues after childhood

Aims: The farming environment in childhood has been reported to decrease the risk of sensitisation to allergens. The purpose of the present study was to explore whether later exposure to...

The 1.8-Å Crystal Structure of Human Tear Lipocalin Reveals an Extended Branched Cavity with Capacity for Multiple Ligands

In contrast with earlier assumptions, which classified human tear lipocalin (Tlc) as an outlier member of the lipocalin protein family, the 1.8-A resolution crystal structure of the recombinant apoprotein confirms the typical eight-stranded antiparallel beta-barrel architecture with an alpha-helix attached to it. The fold of Tlc most closely resembles the bovine dander allergen Bos d 2, a well characterized prototypic lipocalin, but also reveals similarity with beta-lactoglobulin. However, compared with other lipocalin structures Tlc exhibits an extremely wide ligand pocket, whose entrance is formed by four partially disordered loops. The cavity deeply extends into the beta-barrel structure, where it ends in two distinct lobes. This unusual structural feature explains the known promiscuity of Tlc for various ligands, with chemical structures ranging from lipids and retinoids to the macrocyclic antibiotic rifampin and even to microbial siderophores. Notably, earlier findings of biological activity as a thiol protease inhibitor have no correspondence in the three-dimensional structure of Tlc, rather it appears that its proteolytic fragments could be responsible for this phenomenon. Hence, the present structural analysis sheds new light on the ligand binding activity of this functionally obscure but abundant human lipocalin.

Inhalation Challenge With Bovine Dander Allergens: Who Needs It?

To identify which tests would be useful in selecting patients for a specific inhalation challenge with bovine dander allergens (bSIC).A prospective study.A university hospital.Thirty-seven dairy farmers with a clinical suspicion of occupational asthma due to bovine allergens.Each patient (n = 27) underwent histamine challenge, mannitol challenge, exhaled nitric oxide (NO) measurement, bovine-specific serum IgE measurement, and skin-prick test (SPT) with bovine allergens prior to undergoing a bSIC.Eleven patients responded to the inhalation challenge with bovine allergens. The sensitivity and specificity of the tests, based on this response, were 82% and 65%, respectively, for the histamine challenge; 20% and 94%, respectively, for the mannitol challenge; 27% and 77%, respectively, for the NO measurement; 82% and 100%, respectively, for the bovine-specific serum IgE measurement; and 100% and 50%, respectively, for the SPT. Multiple regression analysis revealed that only IgE-mediated sensitivity to bovine allergens, but neither bronchial hyperreactivity nor exhaled NO concentration, contributed significantly to the response.Only the SPT with bovine allergens and bovine-specific serum IgE measurements were useful in selecting patients for the bSIC. This challenge should not be performed in SPT-negative subjects. A diagnosis of occupational asthma due to bovine dander allergens could be made without an inhalation challenge test in asthmatic patients with high bovine-specific serum IgE levels. This practice would eliminate the need for the majority of bSICs.

In vitro and in vivo responses to the recombinant bovine dander allergen Bos d 2 and its fragments.

About one in every four cases of occupational rhinitis recorded in Finland is animal-induced. Bovine allergens are the most important in this respect and the largest patient group consists of dairy farmers. Allergen immunotherapy, if proven effective, safe and feasible, would be ideal for their treatment. The development of recombinant allergens has offered new potential therapeutic prospects. Fragments of recombinant Bos domesticus (Bos d 2) allergen could be suitable for this purpose because they are recognized by T cells but their IgE-binding capacity is attenuated. The aim of this study was to verify whether the potential of the two fragments of recombinant Bos d 2 (corresponding to amino acids 1-131 and 81-172) to induce immediate allergic reaction in a shock organ (nose) was decreased compared to the complete recombinant allergen, which would be an advantageous property for a preparation intended for allergen immunotherapy. The study group consisted of 10 dairy farmers with cow-induced allergic rhinitis. We used the IgE titres against native Bos d 2 measured by indirect IgE ELISA to characterize the level of sensitization and compared the IgE titres in the rhinitis patients with 12 cow-sensitized asthmatic farmers and 12 healthy students. In vitro reactivity against recombinant Bos d 2 and its two fragments was studied by indirect IgE ELISA and in vivo reactivity by nasal provocation tests. The IgE titres against native Bos d 2 of patients with rhinitis tended to be lower than the titres of asthmatics. The healthy students did not exhibit any detectable IgE reactivity to native Bos d 2. In the patients with rhinitis, there was no statistically significant difference between IgE responses against native and recombinant Bos d 2, whereas with both in vitro and in vivo, the reactivity to both fragments of recombinant Bos d 2 was lower than the reactivity to the complete recombinant allergen. Due to the decreased in vivo capacity to induce immediate allergic reactions, the fragments may be better tolerated in allergen immunotherapy than the complete allergen.

Tissue localization of bovine dander allergen Bos d 2

Background: Domestic mammals are important sources of indoor allergens. However, the origin at the tissue level and the biologic function of mammalian allergens are largely unknown. Objective: The aim of this study was to localize the source of the major bovine dander allergen, Bos d 2, in bovine tissues. Methods: Samples from several organs were tested for the presence of mRNA encoding Bos d 2 and Bos d 2 protein by using the reverse transcriptase polymerase chain reaction and immunohistochemical staining, respectively. Results: Skin proved to be the only tissue where mRNA encoding Bos d 2 was detected. This observation was confirmed by immunohistochemistry with a monoclonal anti-Bos d 2 antibody as the primary antibody. In the skin sections, Bos d 2 was found in the secretory cells of apocrine sweat glands and the basement membranes of the epithelium and hair follicles. Bos d 2 belongs to the family of lipocalins comprising a number of pheromone carrier proteins that are present, for example, in the secretions of the apocrine sweat glands. Conclusion: Together with earlier data, our findings suggest that Bos d 2 is produced in sweat glands and transported to the skin surface as a carrier of the pheromone ligand. Because dander allergens of a number of mammalian species are lipocalins, the common biologic function of being pheromone carriers seems to be a common feature of an important group of aeroallergens. (J Allergy Clin Immunol 1998;101:349-53.)

BDA20, a major bovine dander allergen characterized at the sequence level, is Bos d 2

J Allergy Clin Immunol 1997;100:251-2.

Molecular analysis of allergenic proteins in bovine dander

An analytic procedure was established to characterize bovine dander proteins with allergenic properties. The proteins from dander extract were separated by size-exclusion gel filtration, and the fractions were studied with SDS-PAGE followed by immunoblotting. An 11-kDa allergen was found in the same gel filtration fractions as 20- and 22-kDa allergens, and this suggests that the 11-kDa allergen is a dimer in its native form. Our method also detected two separate 22-kDa allergens. The primary structure of the major bovine dander allergen (BDA20) was also studied. A protein sequencer was used to determine the amino acid sequences of enzymatically cleaved peptides. The homology searches revealed that BDA20 is not a previously known bovine protein.

Molecular analysis of allergenic proteins in bovine dander.

An analytic procedure was established to characterize bovine dander proteins with allergenic properties. The proteins from dander extract were separated by size-exclusion gel filtration, and the fractions were studied with SDS-PAGE followed by immunoblotting. An 11-kDa allergen was found in the same gel filtration fractions as 20- and 22-kDa allergens, and this suggests that the 11-kDa allergen is a dimer in its native form. Our method also detected two separate 22-kDa allergens. The primary structure of the major bovine dander allergen (BDA20) was also studied. A protein sequencer was used to determine the amino acid sequences of enzymatically cleaved peptides. The homology searches revealed that BDA20 is not a previously known bovine protein.

Complementary DNA cloning of the predominant allergen of bovine dander: A new member in the lipocalin family

BACKGROUND: A number of allergenic proteins in animal danders have been characterized at the molecular level, but little is known of their biologic functions. We have found that the prevalence of IgE antibodies among patients with cattle-associated asthma is highest against a dander protein referred to as BDA20. OBJECTIVE: The study was performed to characterize the molecular structure of BDA20,* the predominant allergen in bovine dander. METHODS: Clones encoding allergens were identified and isolated from a complementary DNA library by immunoblotting and DNA hybridization and sequenced. Recombinant proteins were produced in Escherichia coli. Immunoreactivity of the recombinant proteins and amino acid sequences of peptides obtained from native BDA20 after Lys-C cleavage were used to identify clones coding for BDA20. RESULTS: In this article we report the cDNA and amino acid sequences of BDA20. Homology comparisons showed that BDA20 belongs to the family of lipocalins. CONCLUSIONS: The results link a dander allergen to a group of functionally important proteins. Lipocalins are present in various body fluids and secretions of several animal species in which they function as carriers of small hydrophobic molecules, such as retinoids and pheromones. If allergenicity proves to be a property shared by lipocalins, our results will have considerable implications for allergen research. (J ALLERGY CLIN IMMUNOL 1996;97:1297-1303.)

117 Bovine dander allergen BDA20 is a lipocalin identical or closely related to Bos d 2

117 Bovine dander allergen BDA20 is a lipocalin identical or closely related to Bos d 2

CDNA Cloning and Protein Analysis of a Bovine Dermal Allergen with Homology to Psoriasin

Immunoscreening of a cDNA library from bovine skin led to isolation of clones coding for an allergen named BDA11. Sequence analysis of the clones revealed that they can encode a protein of 11.6 kDa with a predicted pI of 5.19. Allergenicity of BDA11 was verified by the IgE reactivity in cattle-allergic patients' sera with the recombinant protein produced in Escherichia coli. A biochemically purified native allergen of 11 kDa from bovine dander was identified as BDA11 by peptide sequencing. Homology comparisons showed that BDA11 had a 63.4% amino acid identity with human psoriasin. Psoriasin is a calcium-binding protein expressed in keratinocytes, and it is strongly up-regulated in psoriatic skin. BDA11 also had segments homologous with calcium-binding proteins from three other species.