Bermuda Grass Pollen Research Articles

Nanofluidic point-of-care IgE test for subtropical grass pollen for rapid diagnosis of allergic rhinitis

BackgroundWidening of subtropical climate zones globally and increasing grass-pollen exposure provide the impetus for developing a more precise and accessible diagnosis of allergy. ObjectiveTo evaluate the utility of recombinant allergen components of Panicoideae and Chloridoideae pollens for specific IgE testing in a rapid, point-of-care device. MethodsRecombinant (r) Pas n 1 and Cyn d 1 were expressed, purified, and tested in the nanofluidic device for measuring serum specific IgE (spIgE) in a well-characterized Australian cohort. Concentrations and classes of spIgE to rPas n 1 and rCyn d 1, and total IgE were compared with skin prick test results and spIgE with grass pollen. ResultsCorrelations between commercial and academic laboratories for 21 sera were high for rPas n 1 spIgE (r = 0.695) and total IgE (r = 0.945). Higher spIgE to rPas n 1 and rCyn d 1 fluorescence was detected in the patients with grass-pollen allergy and with clinician-diagnosed allergic rhinitis (n = 134) than in participants with other allergies (n = 49) or no allergies (n = 23). Correlation between spIgE concentrations to rPas n 1 (r = 0.679) and rCyn d 1 (r = 0.548), with Bahia and Bermuda grass-pollen spIgE, respectively, was highly significant (p<0.0001). The positive/negative predictive agreements of spIgE classes for rPas n 1 (73%/82.5%) and rCyn d 1 (67.8%/66.3%) between the nanofluidic and ImmunoCAP measurements for Bahia and Bermuda grass pollen, respectively, were substantial. ConclusionPoint-of-care nanofluidic tests for spIgE to rPas n 1 and rCyn d 1 could increase access to more precise clinical diagnosis for patients with allergies in subtropical regions.

Label-Free Bioaerosol Sensing Using Mobile Microscopy and Deep Learning

Conventional bioaerosol sensing requires the sampled aerosols in the field to be transferred to a laboratory for manual inspection, which can be rather costly and slow, also requiring a professional for labeling and microscopic examination of the samples. Here we demonstrate label-free bioaerosol sensing using a field-portable and cost-effective device based on holographic microscopy and deep-learning, which screens bioaerosols at a throughput of 13 L/min. Two different deep neural networks are designed to rapidly reconstruct the amplitude and phase images of the captured bioaerosols, and to classify the type of each bioaerosol that is imaged. As a proof-of-concept, we studied label-free sensing of common bioaerosol types, for example, Bermuda grass pollen, oak tree pollen, ragweed pollen, Aspergillus spore, and Alternaria spore and achieved >94% classification accuracy. The presented label-free bioaerosol measurement device, with its mobility and cost-effectiveness, will find several applications in indo...

The molecular allergology of subtropical grass pollen

Grass pollens are amongst the most important aeroallergen sources world-wide triggering allergic rhinoconjunctivitis and asthma in sensitised patients. Much of what we know about the allergen components of grasses is informed by research on pollen of temperate (Pooideae) species that are abundant in the temperate climate zones. However, climate changes are altering the biogeographical distribution as well as timing and allergenicity of grass pollens. This provides an impetus for better understanding of the contribution of subtropical subfamilies of grasses to pollen allergy globally. Pollen of Chloridoideae (e.g. Cynodon dactylon; Bermuda grass) and Panicoideae (e.g. Paspalum notatum; Bahia grass or Sorghum halepense; Johnson grass) subfamilies are clinically important in subtropical zones of Australia, Asia, India, Africa, and America. These grasses differ ecologically and phylogenetically from temperate grasses and, importantly their allergen composition is qualitatively different. For example, subtropical grass pollens appear to lack the major group 5 grass pollen allergen family. In this review we summarize current knowledge of the epidemiology and immunology of subtropical Chloridoideae and Pancoideae pollen allergens, describe the biochemical characteristics of known isoforms and variants as well as properties and structures of subtropical pollen allergen components. Whilst only one subtropical allergen component; Cyn d 1 of Bermuda grass pollen, is available commercially for diagnostic use, in a natural purified form, a number of allergens of Panicoideae grass pollen; Zea m 1, Zea m 3 and Zea m 13 of maize, Pas n 1 and Pas n 13 of Bahia, as well as Sor h 1, Sor h 2, Sor h 13 and Sor h 23 of Johnson grass, have been discovered. Research effort is directed towards making available subtropical grass pollen allergen components as innovative treatment and diagnostic options that more specifically address the needs of patients from warmer regions of the globe.

Partial Characterization of Bermuda, Carabao, Cogon and Talahib Grass Pollen Extracts

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The Sensitization Model and Correlation of Bermuda Grass and Timothy Grass Pollen Allergen in Respiratory Allergic Diseases Patients in Southern China

The Sensitization Model and Correlation of Bermuda Grass and Timothy Grass Pollen Allergen in Respiratory Allergic Diseases Patients in Southern China

The Sensitization Model and Correlation of Bermuda Grass and Timothy Grass Pollen Allergen in Respiratory Allergic Diseases Patients in Southern China

The Sensitization Model and Correlation of Bermuda Grass and Timothy Grass Pollen Allergen in Respiratory Allergic Diseases Patients in Southern China

Responsiveness to timothy grass pollen in individuals without known natural exposure in an allergen challenge chamber

BackgroundThe responsiveness to a nonendemic grass species is unknown and cannot be research without an allergen challenge chamber. ObjectiveTo determine the clinical responsiveness to timothy grass pollen (TGP) in participants without known natural exposure in an allergen challenge chamber (ACC). MethodsOf the 26 screened participants, 22 met screening criteria and completed the 2 chamber exposures. The study consisted of an initial screening visit that included a blood draw for serum specific IgE (ssIGE) to Bermuda grass pollen and TGP followed by a 4½-day run-in phase and two 3-hour ACC exposure visits. This study was performed early in the first week of December 2013, when no seasonal pollens were detected in San Antonio, Texas. Symptom scores were recorded at baseline and every 30 minutes. ResultsOf the 26 screened participants, 22 met the screening criteria and completed the 2 chamber exposures. Thirteen participants had always lived in South Texas without natural exposure, and 9 had previously lived in areas with TGP exposure. All participants tested positive to TGP and Bermuda grass pollen. Twelve and 13 of 22 had positive ssIgE test results to Timothy and Bermuda allergens, respectively, with 11 having positive results for both allergens. There were strong correlations among skin prick test size, a positive ssIgE test result, and high symptoms from TGP exposure. There was little difference in symptoms between those who had lived their entire lives in South Texas and those who had lived elsewhere. ConclusionIn Texas, where exposure to TGP is minimal, strongly positive SPT and ssIgE test results were predictors of high symptoms to TGP exposure. Never exposed participants in South Texas reacted to TGP similar to those who had previous natural exposure, suggesting that in vivo cross-reactivity may be higher than predicted by prior in vitro data and may allow the use in clinical trials of allergens not endemic to the locale of an ACC.

Value of microarray allergen assay in the management of eosinophilic oesophagitis

BackgroundEosinophilic oesophagitis (EoE) is a disorder characterised by oesophageal dysfunction and, histologically, by eosinophilic inflammation. Although treatment, which includes dilatations, oral corticosteroids and restrictive diets, is often effective, choosing the foods to be eliminated from the diet is difficult. ObjectiveComponent resolved diagnostic by microarray allergen assay may be useful in detecting allergens that might be involved in the inflammatory process. MethodsWe studied 67 patients with EoE, diagnosed clinically and histologically by endoscopic biopsy. CRD analysis with microarray technology was carried out in the 67 EoE patients, 50 patients with pollen allergy without digestive symptoms, and 50 healthy controls. ResultsAllergies were not detected by microarray in only seven of the 67 patients with EoE. Controls with pollen allergy showed sensitisation to different groups of pollen proteins without significant differences. In EoE patients with response to some allergens, the predominant allergens were grasses group 1 and, in particular, nCyn d 1 (Cynodon dactylon) or Bermuda grass pollen in 59.5%, followed by lipid transfer proteins (LTP) of peach (19.40%), hazelnut (17.91%) and Artemisia (19.40%). ConclusionsIn patients with EoE, sensitisation to plant foods and pollen is important. The proteins most frequently involved are nCyn d 1 and lipid transfer proteins, hazelnuts and walnuts. After one year of an array-guided exclusion diet and pollen-specific immunotherapy in the case of high levels of response, patients with EoE showed preliminary significant improvements.

Neonatal vaccination with plasmid DNA encoding Cyn d 1 effectively prevents allergic responses in mice.

Allergic rhinitis is one of the most common atopic disorders in children. There is no available method to prevent airway sensitization in newborns except allergen avoidance. Recombinant DNA plasmids encoding allergens have been proven to activate Th1 but attenuate Th2-deviated allergic responses in adult animal studies. However, their preventive effects are not presumptive in neonates because of their immature immune function. The aim of this study was to examine the potential preventive effect of a DNA vaccine encoding grass pollen allergen Cyn d 1 on allergic reaction to grass pollen in neonatal mice. Recombinant plasmid Cyn d 1 (pCyn d 1) vaccine was constructed by insertion of Cyn d 1 cDNA into the vector pcDNA3. Neonatal BALB/c mice received the vaccine once on the 3rd day of life or a second dose 2 days later. Control mice received PBS only. Mice were sensitized twice with recombinant Cyn d 1 and alum beginning at 7 weeks of age. Serum antibody responses and cytokine profiles of spleen cells were examined. Neonatal injection with pCyn d 1 vaccine resulted in IgG2a responses and production of interferon gamma in spleen cells. Vaccination with pCyn d 1 also reduced specific IgE responses and spleen cell secretion of IL-4. This study shows the prophylactic effects of DNA vaccine encoding Bermuda grass pollen allergen Cyn d 1 on specific IgE responses in neonatal mice.

In-print of the environment on the molecular sensitisation profile towards pollen allergens revealed by allergen micro-array

Background The green area in Tashkent-city in Uzbekistan has been re-organized during the last two decades. It covers approximately 35% of the total area and includes classical vegetation present in Central Asia such as saltwort and newly planted species such as Bermuda grass. The knowledge of the molecular sensitization profiles of allergic patients is essential for the correct treatment with allergen specific immunotherapy but has not been established for allergic patients in the Central Asian area. Objective The aim of this study was to determine the IgE-sensitization profile towards pollen allergens in patients with respiratory allergy from Tashkent. Methods Fifty adult patients with allergic rhinitis and/or asthma were tested using an allergen micro-array containing 112 different allergen molecules (ImmunoCAP ISAC; Thermo Scientific). Results We found that the major Bermuda grass pollen allergen, Cyn d 1 and the major saltwort allergen Sal k 1 were most frequently recognized allergens. More than 42% of the patients displayed IgE reactivity to Cyn d 1 and the percentage was even higher in the group suffering from allergic asthma (n=12) (i.e., 66%). Sal k 1 was recognized by 46% of the patients and by 50% of the patients with asthma. The other pollen allergens were recognized less frequently. Interestingly, more than 20% of patients showed IgE cross-reactivity with profilins from grass pollen, weed pollen and birch pollen whereas no patient mounted IgE reactivity to the major birch pollen allergen, Bet v 1. Conclusion The results of the IgE profiling identify grass pollen and in particular Bermuda grass and salkwort as the most important pollen allergen sources in Tashkent. Although approximately 20% of the patients reacted with birch pollen profilin, none of the patients reacted with the major birch pollen allergen, Bet v 1, indicating that these patients had no genuine sensitization to birch. These data show that the molecular sensitization profile towards pollen allergens in Central Asia is an in-print of the local flora and indicates how important allergen micro-array analysis is for the selection of the correct immunotherapy treatment. This study was supported by the Austrian Science Fund (FWF), American Austrian Foundation (AAF) and was performed in the framework of International Network University for Molecular Allergology and Immunology.

Allergen sensitization linked to climate and age, not to intermittent-persistent rhinitis in a cross-sectional cohort study in the (sub)tropics.

BackgroundAllergen exposure leads to allergen sensitization in susceptible individuals and this might influence allergic rhinitis (AR) phenotype expression. We investigated whether sensitization patterns vary in a country with subtropical and tropical regions and if sensitization patterns relate to AR phenotypes or age.MethodsIn a national, cross-sectional study AR patients (2-70 y) seen by allergists underwent blinded skin prick testing with a panel of 18 allergens and completed a validated questionnaire on AR phenotypes.Results628 patients were recruited. The major sensitizing allergen was house dust mite (HDM) (56%), followed by Bermuda grass (26%), ash (24%), oak (23%) and mesquite (21%) pollen, cat (22%) and cockroach (21%). Patients living in the tropical region were almost exclusively sensitized to HDM (87%). In the central agricultural zones sensitization is primarily to grass and tree pollen. Nationwide, most study subjects had perennial (82.2%), intermittent (56.5%) and moderate-severe (84.7%) AR. Sensitization was not related to the intermittent-persistent AR classification or to AR severity; seasonal AR was associated with tree (p < 0.05) and grass pollen sensitization (p < 0.01). HDM sensitization was more frequent in children (0-11 y) and adolescents (12-17 y) (subtropical region: p < 0.0005; tropical region p < 0.05), but pollen sensitization becomes more important in the adult patients visiting allergists (Adults vs children + adolescents for tree pollen: p < 0.0001, weeds: p < 0.0005).ConclusionsIn a country with (sub)tropical climate zones SPT sensitization patterns varied according to climatological zones; they were different from those found in Europe, HDM sensitization far outweighing pollen allergies and Bermuda grass and Ash pollen being the main grass and tree allergens, respectively. Pollen sensitization was related to SAR, but no relation between sensitization and intermittent-persistent AR or AR severity could be detected. Sensitization patterns vary with age (child HDM, adult pollen). Clinical implications of our findings are dual: only a few allergens –some region specific- cover the majority of sensitizations in (sub)tropical climate zones. This is of major importance for allergen manufacturers and immunotherapy planning. Secondly, patient selection in clinical trials should be based on the intermittent-persistent and severity classifications, rather than on the seasonal-perennial AR subtypes, especially when conducted in (sub)tropical countries.

Dual Function of Novel Pollen Coat (Surface) Proteins: IgE-binding Capacity and Proteolytic Activity Disrupting the Airway Epithelial Barrier

BackgroundThe pollen coat is the first structure of the pollen to encounter the mucosal immune system upon inhalation. Prior characterizations of pollen allergens have focused on water-soluble, cytoplasmic proteins, but have overlooked much of the extracellular pollen coat. Due to washing with organic solvents when prepared, these pollen coat proteins are typically absent from commercial standardized allergenic extracts (i.e., “de-fatted”), and, as a result, their involvement in allergy has not been explored.Methodology/Principal FindingsUsing a unique approach to search for pollen allergenic proteins residing in the pollen coat, we employed transmission electron microscopy (TEM) to assess the impact of organic solvents on the structural integrity of the pollen coat. TEM results indicated that de-fatting of Cynodon dactylon (Bermuda grass) pollen (BGP) by use of organic solvents altered the structural integrity of the pollen coat. The novel IgE-binding proteins of the BGP coat include a cysteine protease (CP) and endoxylanase (EXY). The full-length cDNA that encodes the novel IgE-reactive CP was cloned from floral RNA. The EXY and CP were purified to homogeneity and tested for IgE reactivity. The CP from the BGP coat increased the permeability of human airway epithelial cells, caused a clear concentration-dependent detachment of cells, and damaged their barrier integrity.Conclusions/SignificanceUsing an immunoproteomics approach, novel allergenic proteins of the BGP coat were identified. These proteins represent a class of novel dual-function proteins residing on the coat of the pollen grain that have IgE-binding capacity and proteolytic activity, which disrupts the integrity of the airway epithelial barrier. The identification of pollen coat allergens might explain the IgE-negative response to available skin-prick-testing proteins in patients who have positive symptoms. Further study of the role of these pollen coat proteins in allergic responses is warranted and could potentially lead to the development of improved diagnostic and therapeutic tools.

Induction of Specific Th1 Responses and Suppression of IgE Antibody Formation by Vaccination with Plasmid DNA Encoding Cyn d 1

Background: DNA vaccines encoding allergens have been developed to prevent or to treat specific IgE responses. Objective: To evaluate the potential preventive and therapeutic effect of DNA vaccines encoding Cyn d 1 alone or combined with different adjuvants on specific allergies. Methods: Recombinant plasmid Cyn d 1 (pCyn d 1) was constructed by insertion of Cyn d 1 cDNA into the vector pcDNA3. BALB/c mice were injected with pCyn d 1 alone or plus adjuvants such as bupivacaine, bestatin, liposome, or CpG. Control mice were treated with pcDNA3 or PBS. They were boosted 3 weeks later and then sensitized twice with recombinant Cyn d 1 and alum. Their serum antibody responses and cytokine profiles of spleen cells were studied. Adoptive transfer of spleen cells of pCyn d 1-vaccinated mice was also performed. Results: Vaccination of mice with pCyn d 1 induced Th1 responses characterized by IgG2a responses and spleen cell secretion of interferon-γ. Vaccination with pCyn d 1 not only prevented the induction of specific IgE responses but also suppressed ongoing IgE responses. The mice receiving untreated, CD4+- or CD8+-depleted spleen cells from pCyn d 1-vaccinated mice all had suppression of IgE responses. Conclusion: This study confirms the prophylactic and therapeutic effects of DNA vaccines encoding Bermuda grass pollen allergen Cyn d 1 on specific IgE responses. Both CD4+ and CD8+ T cells are crucial for the immunomodulatory effect of pCyn d 1 on specific IgE responses.

Bioaerosol detection using potentiometric tomography in flames

A method of detection and identification of bioaerosols is described, based on gaseous plasma electrochemistry in a flame. This approach involves the combustion of individual bioaerosol particles entering a laminar hydrogen/oxygen flame, producing a plume rich in ionised species. As the plume expands and moves through the flame it can be comfortably detected at an array of eight individually addressable electrodes. Zero current potentiometric measurements, simultaneously recorded at each electrode, provide spatial distribution of the combustion plume, which depends on the particle's size, density and chemical make-up. We used a statistical classification analysis extracting specific features of the voltage traces from individual particle combustion events to differentiate between four model bioaerosols (Bermuda grass pollen, Bermuda smut spores, Johnson smut spores and Black walnut pollen). From a set of 120 individual combustion events (30 for each bioaerosol) the best case of identification was correct 29 out of 30 events for Bermuda grass pollen, and the worst being 19 out of 30 for Johnson smut spores. We propose a promising and robust analytical methodology for real-time bioaerosol detection.

Mapping of IgE and IgG4 Antibody-Binding Epitopes in Cyn d 1, the Major Allergen of Bermuda Grass Pollen

Background: Bermuda grass pollen (BGP) is an important seasonal aeroallergen worldwide which induces allergic disorders such as allergic rhinitis, conjunctivitis and asthma. Cyn d 1 is the major allergen of BGP. This study is aimed to map human IgE and IgG₄ antibody-binding sequential epitopes on Cyn d 1 by dot immunoblotting. Methods: Synthetic peptides (10-mers; 5 overlapping residues) spanning the full length of Cyn d 1 were used for dot immunoblotting to map human IgE and IgG_1–4 antibody-binding regions with sera from BGP-allergic patients. Synthetic peptides with more overlapping residues were used for further mapping. Essential amino acids in each epitope were examined by single amino acid substitution with alanine. Peptides with sequence polymorphism of epitopes of Cyn d 1 were also synthesized to extrapolate their differences in binding capability. Results: Four major IgE-binding epitopes (peptides 15^–1, 21, 33^–2 and 35⁺¹, corresponding to amino acids 70–79, 101–110, 159–167 and 172–181) and 5 major IgG₄-binding epitopes (peptides 15^–1, 30^–2, 33^–2, 35⁺¹ and 39, corresponding to amino acids 70–79, 144–153, 159–167, 172–181 and 192–200) were identified. They are all located on the surface of the simulated Cyn d 1 molecule, and three of them are major epitopes for both IgE and IgG₄. Their critical amino acids were all characterized. Major epitopes for human IgG₁ to IgG₄ are almost identical. Conclusions: This is the first study to map the sequential epitopes for human IgE and IgG₄ subclasses in Cyn d 1. It will be helpful for future development in immunotherapy and diagnosis.

Functional immunoglobulin E cross‐reactivity between Pas n 1 of Bahia grass pollen and other group 1 grass pollen allergens

Grass pollens are major triggers of allergic rhinitis and asthma, but the immunological relationships between pollen allergens of the subtropical Bahia grass, Paspalum notatum, and temperate grasses are unresolved. To assess serum IgE cross-reactivity between subtropical P. notatum and temperate Lolium perenne (Ryegrass) pollen allergens. Serum IgE reactivities of grass pollen-allergic patients with P. notatum, L. perenne and Cynodon dactylon (Bermuda grass) pollen extracts and their respective purified group 1 allergens, Pas n 1, Lol p 1 and Cyn d 1, were compared by immunoblotting, ELISA and basophil activation. In a cohort of 51 patients from a temperate region, a high frequency of IgE reactivity with each grass pollen was detected, but reactivity with L. perenne pollen was substantially greater than with P. notatum and C. dactylon pollen. Similarly, serum IgE reactivity with Lol p 1 was greater than with Pas n 1 or Cyn d 1. For seven of eight sera studied in detail, asymmetric serum IgE cross-reactivity was observed; L. perenne pollen inhibited IgE reactivity with P. notatum pollen but not the converse, and IgE reactivity with Pas n 1 was inhibited by Lol p 1 but IgE reactivity with Lol p 1 was not inhibited by Pas n 1 or Cyn d 1. Importantly, P. notatum pollen and Pas n 1 activated basophils in grass pollen-allergic patients from a temperate region, although stimulation was greater by pollen of L. perenne than P. notatum or C. dactylon, and by Lol p 1 than Pas n 1 or Cyn d 1. In contrast, a cohort of 47 patients from a subtropical region showed similar IgE reactivity with P. notatum and L. perenne pollen, and reciprocal cross-inhibition of IgE reactivity between L. perenne and P. notatum. Pollen allergens of the subtropical P. notatum, including Pas n 1, show clinically relevant IgE cross-reactivity with pollen allergens of L. perenne but also species-specific IgE reactivity.

Potentiometric Detection of Model Bioaerosol Particles

A new technique for the detection of bioaerosols is presented, utilizing particle combustion/ionization in a premixed hydrogen/oxygen/nitrogen flame plasma, followed by gas phase electrochemical detection. Bermuda grass pollen (Cynodon dactylon, one of the most common causes of pollen allergy) and black walnut pollen (Juglans nigra) were used as model bioaerosol particles. We demonstrate that single particle detection can be comfortably achieved by zero current potential measurements between two platinum electrodes, giving potential signals of over 800 mV and unique fragmentation features which may be used for differentiating between species. The high sensitivity is due to the inherent amplification through flame fragmentation, gasification and ionization; a single pollen grain of 25 μm diameter can give a plume of combustion products measuring 4 mm in diameter. The physical basis of the potential difference is a mixed interfacial potential with an additive diffusion/junction potential due to the increase in ionization from the pollen combustion. The results suggest this methodology may be applied to the detection of particulates composed of ionizable species (organic or inorganic) in gaseous environments, such as bacteria, viruses, pollen grains, and dust. Its effectiveness will depend on the propensity of the target particle to combust and generate voltages under specific flame and electrode conditions.

Functional Interaction of Common Allergens and a C-type Lectin Receptor, Dendritic Cell-specific ICAM3-grabbing Non-integrin (DC-SIGN), on Human Dendritic Cells

Fucosylated glycans on pathogens are known to shape the immune response through their interaction with pattern recognition receptors, such as C-type lectin receptors (CLRs), on dendritic cells (DCs). Similar fucosylated structures are also commonly found in a variety of allergens, but their functional significance remains unclear. To test a hypothesis that allergen-associated glycans serve as the molecular patterns in functional interaction with CLRs, an enzyme-linked immunosorbent assay-based binding assay was performed to determine the binding activity of purified allergens and allergen extracts. THP-1 cells and monocyte-derived DCs (MDDCs) were investigated as a model for testing the functional effects of allergen-CLR interaction using enzyme-linked immunosorbent assay, Western blotting, and flow cytometry. Significant and saturable bindings of allergens and allergen extracts with variable binding activities to DC-specific ICAM3-grabbing non-integrin (DC-SIGN) and its related receptor, L-SIGN, were found. These include bovine serum albumin coupled with a common glycoform (fucosylated glycan lacking the alpha1,3-linked mannose) of allergens and a panel of purified allergens, including BG60 (Cyn dBG-60; Bermuda grass pollen) and Der p2 (house dust mite). The binding activity was calcium-dependent and inhibitable by fucose and Lewis-x trisaccharides (Le(x)). In THP-1 cells and human MDDCs, BG60-DC-SIGN interaction led to the activation of Raf-1 and ERK kinases and the induction of tumor necrosis factor-alpha expression. This effect could be blocked, in part, by Raf-1 inhibitor or anti-DC-SIGN antibodies and was significantly reduced in cells with DC-SIGN knockdown. These results suggest that allergens are able to interact with DC-SIGN and induce tumor necrosis factor-alpha expression in MDDCs via, in part, Raf-1 signaling pathways.

Food allergy in children: threshold distribution curves for 6 major food allergens

Background The subtropical Bahia grass (Paspalum notatum) is an important source of pollen allergens with an extended season of pollination and wide distribution in warmer climates. The immunological relationship between pollen allergens of Bahia grass and temperate grasses is unresolved. Methods Serum IgE reactivity of grass pollen-allergic patients with Bahia, Ryegrass and Bermuda grass pollen extracts and their purified group 1 allergens, Pas n 1, Lol p 1 and Cyn d 1, were compared by immunoblotting, ELISA, inhibition ELISA, basophil activation by flow cytometry and molecular modeling. Results Differences in antibody recognition of allergenic components between Bahia grass and Ryegrass pollen were observed by immunoblotting. Eight grass pollen-allergic patients from a temperate region showed greater serum IgE reactivity with Ryegrass pollen than Bahia grass by ELISA. For seven of these sera, Ryegrass pollen inhibited IgE reactivity with Bahia grass pollen but not the converse. For 51 sera from grass pollen-allergic patients in this temperate region, IgE reactivity with Lol p 1 was greater than Pas n 1 or Cyn d 1. IgE reactivity with Lol p 1 was not inhibited by Pas n 1 or Cyn d 1, but Pas n 1 IgE reactivity was inhibited by Lol p 1. Two group 1 grass pollen allergen-specific mAb distinguished between temperate and subtropical grass pollens. Basophil activation for three patients tested was greater by Ryegrass pollen than Bahia or Bermuda grass, and by Lol p 1 than Pas n 1 or Cyn d 1. In contrast, two patients from a subtropical region had higher serum IgE reactivity with Bahia grass pollen than Ryegrass and Bahia grass pollen inhibited IgE reactivity with Ryegrass. A structural model of Pas n 1 showed amino acids implicated in IgE epitopes of other group 1 allergens were juxtaposed on the surface. Conclusion Allergens from subtropical Bahia grass pollen, including Pas n 1, share antigenic determinants with temperate grass pollen allergens, but patients exhibit higher serum IgE reactivity to their locally predominant grass pollen. Basophil activation by Bahia grass pollen and Pas n 1 in patients from a temperate climate indicates clinically relevant cross-sensitization between temperate and subtropical grass pollens.

Mapping of IgE-binding regions on recombinant Cyn d 1, a major allergen from Bermuda Grass Pollen (BGP)

BackgroundBermuda grass (Cynodon dactylon; subfamily Chloridoideae) is an important source of seasonal aeroallergens in warm tropical and sub-tropical areas worldwide. Improved approaches to diagnosis and therapy of allergic diseases require a thorough understanding of the structure and epitopes on the allergen molecule that are crucial for the antigen-antibody interaction. This study describes the localization of the human IgE-binding regions of the major group 1 pollen allergen Cyn d 1 from Bermuda grass.MethodsA cDNA library was constructed from Bermuda grass pollen (BGP) using a Lambda gt11 expression vector. The gene encoding the Cyn d 1 allergen was isolated by screening the library with a mouse monoclonal antibody raised against grass group 1 allergen. In order to characterize the IgE epitopes on Cyn d 1, seven overlapping fragments and three deletion mutants were cloned and over-expressed in E. coli. The recombinant fragments and deletion mutants were evaluated for their comparative IgE reactivity with sera of non atopic individuals and grass pollen allergic patients by ELISA and a dot-blot assay.ResultsAnalysis of IgE binding regions by overlapping fragments and deletion mutants identified two major allergenic regions corresponding to amino acids 120–170 and 224–244. Deletion of either or both regions led to a significant reduction in IgE binding, emphasizing the importance of the C-terminal region on Cyn d 1 in epitope-IgE interaction.ConclusionAnti-Cyn d 1 IgE antibodies from allergic human sera recognize two epitopes located at the C-terminal end of the molecule. These data will enable the design of improved diagnostic and therapeutic approaches for BGP hypersensitivity.