(1-->3)-beta-D-glucan may contribute to pollen sensitivity

Effect of Honey and Syrup Diets Enriched with 1,3-1,6 β-Glucans on Honeybee Survival Rate and Phenoloxidase Activity (Apis mellifera L. 1758)

β-glucans can activate the animal innate immune system by acting as immune-modulators and inducing various stimulatory effects. The aim of this study was to investigate the effect of 1,3-1,6 β-glucans administered orally for 96 h on Apis mellifera workers (newly emerged and nurse bees). β-glucans were included in honey and syrup. Survival rate and phenoloxidase activity were measured. In both newly emerged and nurse bees, β-glucans supplementation did not affect survival rate (p > 0.05). Conversely, phenoloxidase activity was higher in both newly emerged bees (p = 0.048) and nurse bees (p = 0.014) fed with a honey diet enriched with β-glucans compared to those fed with only honey. In both the newly emerged and nurse bees, no statistical differences in phenoloxidase activity were recorded between the group fed with a syrup-based diet enriched with β-glucans and the control group (p > 0.05). The absence of significant variation in survival suggests that the potential negative effect of β-glucans in healthy bees could be mitigated by their metabolism. Conversely, the inclusion of β-glucans in a honey-based diet determined an increase of phenoloxidase activity, suggesting that the effect of β-glucan inclusion in the diet of healthy bees on phenoloxidase activity could be linked to the type of base-diet. Further investigations on β-glucans metabolism in bees, on molecular mechanism of phenoloxidase activation by 1,3-1,6 β-glucans, and relative thresholds are desirable. Moreover, investigation on the combined action of honey and β-glucans on phenoloxidase activity are needed.

Development of a Highly Sensitive β-Glucan Detection System Using Scanning Single-Molecule Counting Method

To overcome the limitations of the Limulus amebocyte lysate (LAL) assay method for the diagnosis of invasive fungal infection, we applied a reaction system combining recombinant β-glucan binding proteins and a scanning single-molecule counting (SSMC) method. A novel (1→3)-β-D-glucan recognition protein (S-BGRP) and a (1→6)-β-glucanase mutant protein were prepared and tested for the binding of (1→6)-branched (1→3)-β-D-glucan from fungi. S-BGRP and (1→6)-β-glucanase mutant proteins reacted with β-glucan from Candida and Aspergillus spp. Although LAL cross-reacted with plant-derived β-glucans, the new detection system using the SSMC method showed low sensitivity to plant (1→3)-β-D-glucan, which significantly improved the appearance of false positives, a recognized problem with the LAL method. Measurement of β-glucan levels by the SSMC method using recombinant β-glucan-binding proteins may be useful for the diagnosis of fungal infections. This study shows that this detection system could be a new alternative diagnostic method to the LAL method.

Equine respiratory viruses, airway inflammation and performance in thoroughbred racehorses

Equine asthma is a common cause of poor performance in racehorses but it is unclear if respiratory viruses contribute to its etiology. The objective of the study was to determine if respiratory viruses were associated with clinical signs and bronchoalveolar lavage fluid (BALF) cytology in Thoroughbred racehorses. Equine herpesviruses (EHV-1, 2, 4, 5) and equine rhinitis A and B viruses (ERBV, ERAV) genomes were quantified by qPCR in nasopharyngeal, tracheal, and BALF samples collected after racing. The relationships between virus detection and load and clinical signs, performance, BALF cytology, and environmental exposures were examined with generalized linear mixed models. Ninety-two samples were collected from 31 horses. EHV-1 and ERAV were not found; EHV-4 was detected in only one sample. EHV-2, EHV-5 and ERBV were more likely to be detected in upper airway samples than in BALF (P < 0.0001). Neither respiratory virus detection nor load was associated with clinical signs or performance. Nasopharyngeal detection and load of ERBV and tracheal detection and load of EHV-5 were associated with increased proportions of neutrophils in BALF (P < 0.003). However, nasopharyngeal detection and load of EHV-5 was not (P = 0.11). Nasopharyngeal detection and load of EHV-2 were associated with decreased BALF mast cell proportions. Respirable dust exposures were significantly higher in horses with detection of ERBV when compared to horses with no detectable ERBV (P < 0.001). Our results suggest that ERBV, EHV-2 and EHV-5 are commonly present in upper airways of healthy racehorses; however, the role they play in the etiology of equine asthma remains unclear.

Possibility of Japanese Cedar Pollen Causing False Positives in the Deep Mycosis Test

Because Japanese cedar pollen (JCP) contains beta-1,3-d-glucan (BG), there is concern that its lingering presence in the atmosphere, especially during its scattering period, may cause false positives in the factor-G-based Limulus amebocyte lysate (LAL) assay used to test for deep mycosis (i.e., G-test). Hence, we examined whether the LAL assay would react positively with substances contained in JCP by using the G-test to measure JCP particles and extracts. BG was purified from the JCP extract on a BG-specific affinity column, and the percentage extractability was measured using three different BG-specific quantitative methods. The G-test detected 0.4 pg BG in a single JCP particle and 10 fg from a single particle in the extract. The percentage extractability of JCP-derived BG was not significantly different among the three quantitative methods. As the JCP particles should technically have been removed during serum separation, they should be less likely to be a direct false-positive factor. However, given that the LAL-assay-positive substances in the JCP extract were not distinguishable by the three BG-specific quantitative methods, we conclude that they may cause the background to rise. Therefore, in Japan false positives arising from JCP contamination should be considered when testing patients for deep mycosis.

Latent 1,3-β-D-glucan acts as an adjuvant for allergen-specific IgE production induced by Japanese cedar pollen exposure

BACKGROUND

The pollen grains of several plant species contain 1,3-β-D-glucan (BG). BG activates dendritic cells (DCs) and subsequently regulates the innate immune responses. Within Japan, the most common disease associated with type-I hypersensitivity is Japanese cedar pollinosis. However, the role of BG in Japanese cedar pollen (JCP) remains unclear. This study examined the localization and immunological effects of BG in JCP.

METHODS

The localization of BG in JCP grain was determined by immunohistochemical staining using a soluble dectin-1 protein probe and a BG recognition protein (BGRP). The content of BG extracted from JCP was measured by a BGRP-based ELISA-like assay. The cytokine production by bone marrow-derived DCs (BMDCs) obtained from wild-type and BG receptor (dectin-1) knock-out mice was examined in vitro. The mice were intranasally administered JCP grains and the specific serum Ig levels were then quantified.

RESULTS

BG was detected in the exine and cell wall of the generative cell and tube cell of the JCP grain. Moreover, BG in the exine stimulated production of TNF-α and IL-6 in the BMDCs via a dectin-1-dependent mechanism. Meanwhile, JCP-specific IgE and IgG were detected in the serum of wild-type mice that had been intranasally administered with JCP grains. These mice also exhibited significantly enhanced sneezing behavior. However, dectin-1 knock-out mice exhibited significantly lower JCP-specific IgE and IgG levels compared to wild-type mice.

CONCLUSIONS

Latent BG in JCP can act as an adjuvant to induce JCP-specific antibody production via dectin-1.

β-Glucans in standardized allergen extracts

Background: Allergen extracts contain variable quantities of bacterial endotoxin. Recent studies have suggested that (1→3)-β-D-glucans (β-glucans), also microbial cell wall components, may have adjuvant properties that could affect allergen immunotherapy.

Objective: To determine the quantities of β-glucans in standardized allergen extracts.

Materials and Methods : Ninety-four lots of 13 standardized allergen extracts were tested for β-glucan content by Glucatell assay, and for endotoxin content by a specific, chromogenic formulation of the Limulus amebocyte lysate test.

Results: Standardized allergen extracts contain variable quantities of endotoxins and β-glucans. As in our previous work, endotoxin activity was greatest in cat pelt and Dermatophagoides farinae, and least in the pollens. There was no correlation between endotoxin and β-glucan levels ( r = 0.1887; P = 0.07). β-Glucan content was highest for grass pollen (median content, 10.6 ng/ml; range, 0.4—41.8 ng/ml), ragweed pollen (32.9 ng/ml; range, 6.5—41.2 ng/ml), and cat pelt (25.5 ng/ml; range, 16.7—41.1 ng/ml), and lowest for cat hair (4.9 ng/ml; range, 1.2—10.3 ng/ml), D. farinae (1.2 ng/ml; range, 0.4—5.2 ng/ml) and Dermatophagoides pteronyssinus (1.8 ng/ml; range, 0.4—6.7 ng/ml).

Conclusions: β-Glucans are present in standardized allergen extracts. The effects of these quantities of β-glucans on allergen immunotherapy and allergen skin testing require further study.

β-Glucans in the treatment and prevention of allergic diseases

β-glucans are a group of biologically active polysaccharides of natural origin with a proven pleiotropic immunomodulation effect. Their efficacy has been confirmed in the therapeutic treatment and prevention of various infectious diseases, secondary immune defects and also of oncologic disorders. Allergic diseases are one of the most frequent diseases and their prevalence continues to increase. They develop as a consequence of dysregulation of the immune system, especially when there is failure in the equilibrium of the response of TH1/TH2 lymphocytes towards TH2. New therapeutic approaches in the treatment of immunopathological conditions (e.g. allergic or oncologic) are directed to restoring the equilibrium among different T lymphocyte subpopulations. Based on in vitro experiments, and also on animal and human clinical studies, there is much evidence for the importance of β-glucans in the treatment and also prevention of allergic diseases; this opens new perspectives on the use of this widespread and popular group of natural substances.

Characterization of the monthly variation in (1 → 3)-β-D-glucan concentrations in university laboratories

We characterize the monthly variation in (1 → 3)-β-D-glucan concentration measured over the course of 1 year, and we evaluate the characteristics of size selection using a two-stage cyclone sampler. The (1 → 3)-β-D-glucan concentrations were measured in four bio-related laboratories. A total of 156 samples were collected using a new two-stage cyclone sampler. Analysis of (1 → 3)-β-D-glucan was performed using the kinetic Limulus amebocyte lysate assay. The study showed that airborne (1 → 3)-β-D-glucan concentrations were significantly higher in laboratory D (mean ± SD 1,105 ± 1,893 pg/m(3)) and in the spring (5,458 pg/m(3)). The highest concentration of (1 → 3)-β-D-glucan occurred in the spring, particularly in May.

Key role of water-insoluble allergens of pollen cytoplasmic granules in biased allergic response in a rat model

BACKGROUND

: Grass pollen grain, an important aeroallergen, can disperse in the environment pollen cytoplasmic granules (PCGs) able to release water-soluble allergens when they are washed out by rainfall. The allergenicity of these washed PCGs is, however, preserved.

OBJECTIVE

: The purpose of the study was to assess the allergenic potential of washed and unwashed PCGs, from Phleum pratense pollen grains, in the Brown Norway rat, and to study the IgE reactivity of sera of sensitized rats to water-soluble and water-insoluble extracts of PCGs and pollen grains.

METHODS

: Rats were sensitized and challenged intratracheally with washed or unwashed PCGs or pollen grains. Using water-soluble and -insoluble extracts of pollen grains and/or PCGs, IgE ELISA and immunoblotting were performed with rat sera. Proliferation of bronchial lymph node cells was monitored by [H]-thymidine incorporation in a lymph node assay. Alveolar cells, proteins, and TH1 and TH2 cytokines were quantified in bronchoalveolar lavage fluid.

RESULTS

: Rats sensitized with unwashed PCGs showed a predominant humoral response with high serum IgE and reactivity to water-soluble and -insoluble proteins together with low lymph node cell proliferation. Conversely, in rats sensitized to washed PCGs, cellular responses were higher with significant increases in eosinophils, lymphocytes, and TH2 cytokines observed in bronchoalveolar lavage fluid.

CONCLUSION

: Allergic and inflammatory responses were induced by both grass pollen grains and their isolated washed and unwashed PCGs. However, on the basis of humoral and cellular responses, differential patterns were observed. Water-insoluble allergens seem to play a role in the centrally mediated inflammatory response, whereas water-soluble allergens may be involved in the peripheral humoral response.

Airborne microorganisms, endotoxin, and (1→3)-β-D-glucan exposure in greenhouses and assessment of respiratory symptoms among workers

OBJECTIVES

Greenhouse operations are an important sector of the horticulture industry, also known as the Green Industry. The objectives of this study were (i) to investigate exposure levels to airborne culturable fungi, bacteria (total culturable bacteria and actinomycetes), endotoxin, and (1→3)-β-D-glucan in three Midwest greenhouses during summer and winter using multiple exposure assessment methods; (ii) characterize the load of microorganisms on greenhouse floors and determine potential microbial source strengths of the floors for aerosolizing microbial biocontaminants, and (iii) to estimate the prevalence of rhinitis, wheezing, asthma, and other respiratory symptoms/conditions among greenhouse workers.

METHODS

Stationary inhalable aerosol samples were collected from each greenhouse using Button Inhalable Aerosol Samplers. Control samples were collected from offices and nearby outdoor locations. A microbial source strength tester was used to examine the aerosolization potential of microbial contaminants from greenhouse floors. Additionally, surface samples were collected by sterile cotton swabs. Temperature, relative humidity, and wind velocity were recorded. Airborne culturable fungi, bacteria, and actinomycetes were analyzed in the extracts from field samples by cultivation in nutrient agar media. Endotoxin and (1→3)-β-D-glucan in the extracts from field samples were analyzed by specific kinetic chromogenic Limulus amebocyte lysate assays. The prevalence of respiratory symptoms among greenhouse workers (n = 35) and control subjects (office workers; n = 14) was estimated with a standardized questionnaire.

RESULTS AND CONCLUSIONS

The collected data indicate that workers employed in Midwest greenhouses may be exposed to elevated levels of inhalable culturable microorganisms (fungi and bacteria collectively on the order of 10(2)-10(5) CFU m(-3)), endotoxin (10(1)-10(3) EU m(-3)), and (1→3)-β-D-glucan (10(1)-10(2) ng m(-3)). Seasonal variations were observed for some bioaerosol components. The prevalence of self-reported respiratory symptoms was generally higher among greenhouse workers compared to controls; however, the differences were not statistically significant, likely due to the relatively low statistical power of the study.

Immunomodulatory activities and subacute toxicity of a novel β-glucan from Paenibacillus polymyxa JB115 in rats

Subacute toxicity and immunopharmacological activities of β-glucan from P. polymyxa JB115 was evaluated in a 28-day feeding study in rats. The white blood cell count, red blood cell count, hematocrit, hemoglobin, thrombocytes (THR) and thrombocytocrit were significantly higher in male fed with β-glucan than control rats and the insignificant lower eosinophil count, mean corpuscular volume, mean cell hemoglobin and uninfected THR (uTHR) levels were observed in male whereas no marked changes in female rats. No other significant differences in serum chemistry and liver, kidney, and spleen weights were observed. The pathological changes and other abnormal indicators were not detected in urine. Female rats fed with diet supplemented with 0.01% β-glucan also showed marked increase in the percentage of blood cytotoxic T-lymphocytes compared to that of the control group while not significant differences in the percentage of blood B-lymphocytes. No adverse effects on general condition and behavior, growth, feed and water consumption and feed conversion efficiency were found. The results suggest that consumption of the novel β-1, 3/1, 6-glucan from P. polymyxa JB115 was not associated with any obvious toxic effects in rats, indicating its safety as a potential immunostimulant or as an adjuvant of some animal vaccines.

Immunological Interactive Effects between Pollen Grains and Their Cytoplasmic Granules on Brown Norway Rats

BACKGROUND

: Grass pollen is one of the most important aeroallergen vectors in Europe. Under some meteorological factors, pollen grains can release pollen cytoplasmic granules (PCGs). PCGs induce allergic responses. Several studies have shown that during a period of thunderstorms the number of patients with asthma increases because of higher airborne concentrations of PCGs.

OBJECTIVE

: The aims of the study were to assess the allergenicity of interactive effects between pollen and PCGs and to compare it with allergenicity of Timothy grass pollen and PCGs in Brown Norway rats.

METHODS

: Rats were sensitized (day 0) and challenged (day 21) with pollen grains and/or PCGs. Four groups were studied: pollen-pollen (PP), PCGs-PCGs (GG), pollen-PCGs (PG), and PCGs-pollen (GP). Blood samples, bronchoalveolar lavage fluid, and bronchial lymph node were collected at day 25. IgE and IgG1 levels in sera were assessed by enzyme-linked immunosorbent assay. Alveolar cells, protein, and cytokine concentrations were quantified in bronchoalveolar lavage fluid. T-cell proliferation, in response to pollen or granules, was performed by lymph node assay.

RESULTS

: Interactive effects between pollen and PCGs increased IgE and IgG1 levels when compared with those of the negative control. These increases were lower than those of the PP group but similar to the levels obtained by the GG group. Whatever was used in the sensitization and/or challenge phase, PCGs increased lymphocyte and Rantes levels compared with those of the pollen group. The interactive effects increased IL-1α and IL-1β compared with those of the PP and GG groups.

CONCLUSIONS

: Immunologic interactive effects have been shown between pollen and PCGs. For humoral and cellular allergic responses, interactive effects between the 2 aeroallergenic sources used in this study seem to be influenced mainly by PCGs.

Use of (1-3)-beta-d-glucan concentrations in dust as a surrogate method for estimating specific fungal exposures

Indoor exposure to fungi has been associated with respiratory symptoms,often attributed to their cell wall component, (1-3)-beta-D-glucan. Performing(1-3)-beta-D-glucan analysis is less time consuming and labor intensive than cultivation or microscopic counting of fungal spores. This has prompted many to use(1-3)-beta-D-glucan as a surrogate for fungal exposure. The aim of this study was to examine which indoor fungal species are major contributors to the (1-3)-beta-D-glucan concentration in field dust samples. We used the quantitative polymerase chain reaction (QPCR) method to analyze 36 indoor fungal species in 297 indoor dust samples. These samples were also simultaneously analyzed for (1-3)-beta-D-glucan concentration using the endpoint chromogenic Limulus Amebocyte lysate assay. Linear regression analysis, followed by factor analysis and structural equation modeling, were utilized in order to identify fungal species that mostly contribute to the (1-3)-beta-D-glucan concentration in field dust samples. The study revealed that Cladosporium and Aspergillus genera, as well as Epicoccum nigrum, Penicillium brevicompactum and Wallemia sebi were the most important contributors to the (1-3)-beta-D-glucan content of these home dust samples. The species that contributed most to the (1-3)-beta-D-glucan concentration were also the most prevalent in indoor environments. However, Alternaria alternata, a common fungal species in indoor dust, did not seem to be a significant source of (1-3)-beta-D-glucan.

PRACTICAL IMPLICATIONS

This study revealed that the (1-3)-beta-D-glucan content of different fungal species varies widely. (1-3)-beta-D-glucan inhouse dust from the Greater Cincinnati area may be a good marker for some fungal species of the Cladosporium and Aspergillus genera. In contrast, Alternaria alternata did not contribute much to the (1-3)-beta-D-glucan load. Therefore, (1-3)-beta-D-glucan concentration in field samples as a surrogate for total fungal exposure should be used with caution.

Advances in functional research of antioxidants and organoleptic traits in berry crops

Berry species are economically-important crops worldwide and represent an invaluable source of vitamins and other health-related compounds. Species belonging to the families Rosaceae, Ericaceae and Grossulariaceae provide the most popular fruits, showing a strong diversity in natural and breeding populations as to berry traits (fruit type, size, color, flavor, antioxidant capacity), resistance to a/biotic stress, adaptation to different environment/culture conditions. The small genome size of most diploid berry genera is a remarkable feature for last-generation genomics technologies, molecular genetics and functional studies. This review will cover the literature dealing with molecular research in berry crops, focusing on antioxidant- and flavor-related compounds.

Potentiation of histamine release by Microfungal (1-->3)- and (1-->6)-beta-D-glucans

(1-->3)-beta-D-Glucans, a cell wall component in most microfungi, are suggested to play a role in the development of respiratory and general symptoms in organic dust-related diseases. The mechanisms by which they induce these effects are, however, not clear. In the present study, mediator release and its potentiation by the (1-->3)-beta-D-glucan as well as by the (1-->6)-beta-D-glucan found in yeast and other fungi were therefore examined. Blood leucocytes from healthy volunteers and from patients allergic to house dust mite were incubated with (1-->3)-beta-D-glucans with increasing 1,6-branchings: curdlan [a linear (1-->3)-beta-D-glucan], laminarin and scleroglucan, and furthermore with pustulan, a linear (1-->6)-beta-D-glucan. Histamine release was not observed on exposure to the glucans only, but in the presence of anti-immunoglobulin E (IgE) antibody or specific antigens, all the glucans investigated led to an enhancement of the IgE-mediated histamine release. The glucans induced a significant potentiation of the mediator release when present at concentrations in the range of 2-5 x 10(-5) M. These results suggest that (1-->3)-beta-D-glucan as well as (1-->6)-beta-D-glucan aggravates IgE-mediated histamine release. Knowledge concerning the effects of glucans on immune responses may be of importance for understanding and treating inflammatory and allergic diseases.

House dust (1-3)-beta-D-glucan and wheezing in infants

BACKGROUND

(1-3)-Beta-D-glucan is a fungal cell wall component, suspected to cause respiratory symptoms in adults. However, very little is known on the possible health effects of (1-3)-beta-D-glucan during infancy. We examined the association between (1-3)-beta-D-glucan exposure and the prevalence of allergen sensitization and wheezing during the first year of life in a birth cohort of 574 infants born to atopic parents. Endotoxin exposure was included as a possible confounder.

METHODS

(1-3)-Beta-D-glucan and endotoxin exposures were measured in settled dust collected from infants' primary activity rooms. The primary outcomes at approximately age one included parental reports of recurrent wheezing and allergen sensitization evaluated by skin prick testing to a panel of 15 aeroallergens as well as milk and egg white.

RESULTS

Exposure to high (1-3)-beta-D-glucan concentration (within fourth quartile) was associated with reduced likelihood of both recurrent wheezing [adjusted OR (aOR) = 0.39, 95% CI = 0.16-0.93] and recurrent wheezing combined with allergen sensitization (aOR = 0.13, 95% CI = 0.03-0.61). Similar trends were found between (1-3)-beta-D-glucan concentrations and allergen sensitization (aOR = 0.57, 95% CI = 0.30-1.10). In contrast, recurrent wheezing with or without allergen sensitization was positively associated with low (1-3)-beta-D-glucan exposure within the first quartile (aOR = 3.04, 95% CI = 1.25-7.38; aOR = 4.89, 95% CI = 1.02-23.57). There were no significant associations between endotoxin exposure and the studied health outcomes.

CONCLUSIONS

This is the first study to report that indoor exposure to high levels of (1-3)-beta-D-glucan (concentration >60 microg/g) is associated with decreased risk for recurrent wheezing among infants born to atopic parents. This effect was more pronounced in the subgroup of allergen-sensitized infants.

(1-->3)-beta-D-glucan does not induce acute inflammation after nasal deposition

To assess if (1→3)-β-D-glucan, a microbial cell wall agent normally present in pollen, has the ability to produce pollenlike response, sensitive persons received a nasal deposition of two doses of (1→3)-β-D-glucan. The percentage of eosinophils and amount of eotaxin were measured in nasal lavage 30 minutes and 24 hours after challenge. No effect could be demonstrated. The absence of an inflammatory response after (1→3)-β-D-glucan application confirms earlier findings in inhalation studies.

Fruit cross-reactive allergens: a theme of uprising interest for consumers' health

Regular consumption of fruits has a positive influence on human health by disease prevention. However parallel to dietetic benefits, IgE-mediated fruit allergies have been shown to be an increasing health risk for children and adults in the Northern hemisphere. The spectrum of food allergies ranges from chronic symptoms to more acute problems and even anaphylaxis. Fruit proteins with high primary sequence similarity display also homologous tertiary structures, resulting in similar epitopes to IgEs and consequently in cross-reactivity. In this review we present the major allergens of stone and pome fruits and discuss the presence of homologous proteins in small fruits. Interestingly these proteins, which might pose an allergenic potential for pre-sensitised individuals are expressed also in strawberry, raspberry and blueberry, otherwise rich in beneficial biofactors.

Phleum pratense pollen starch granules induce humoral and cell-mediated immune responses in a rat model of allergy

BACKGROUND

Timothy grass (Phleum pratense) pollen allergens are an important cause of allergic symptoms. However, pollen grains are too large to penetrate the deeper airways. Grass pollen is known to release allergen-bearing starch granules (SG) upon contact with water. These granules can create an inhalable allergenic aerosol capable of triggering an early asthmatic response and are implicated in thunderstorm-associated asthma.

OBJECTIVE

We studied the humoral (IgE) and bronchial lymph node cells reactivities to SG from timothy grass pollen in pollen-sensitized rats.

METHODS

Brown-Norway rats were sensitized (day 0) and challenged (day 21) intratracheally with intact pollen and kept immunized by pollen intranasal instillation by 4 weeks intervals during 3 months. Blood and bronchial lymph nodes were collected 7 days after the last intranasal challenge. SG were purified from fresh timothy grass pollen using 5 microm mesh filters. To determine the humoral response (IgE) to SG, we developed an original ELISA inhibition test, based on competition between pollen allergens and purified SG. The cell-mediated response to SG in the bronchial lymph node cells was determined by measuring the uptake of [3H]thymidine in a proliferation assay.

RESULTS

An antibody response to SG was induced, and purified SG were able to inhibit the IgE ELISA absorbance by 45%. Pollen extract and intact pollen gave inhibitions of 55% and 52%, respectively. A cell-mediated response was also found, as pollen extract, intact pollen and SG triggered proliferation of bronchial lymph node cells.

CONCLUSIONS

It was confirmed that timothy grass pollen contains allergen-loaded SG, which are released upon contact with water. These granules were shown to be recognized by pollen-sensitized rats sera and to trigger lymph node cell proliferation in these rats. These data provide new arguments supporting the implication of grass pollen SG in allergic asthma.

Modified endotoxin responses in rats pretreated with 1-->3-beta-glucan (zymosan A)

The present study investigates whether 1-->3-beta-glucans (zymosan particles) modify the pulmonary response of rats to endotoxin (lipopolysaccharide, LPS). Initial experiments were conducted to establish appropriate doses of LPS and regimens for exposure to zymosan and LPS. Interaction between zymosan and LPS exposures was determined to be the deviation from the sum of the individual effects of these agents. Treatment with zymosan on Day 1 and LPS on Day 2 modified several indices of pulmonary responsiveness, including tumor necrosis factor-alpha, albumin, and lactate dehydrogenase activity (LDH) in first acellular lavage fluid as well as the levels of chemiluminescence (CL), NO-dependent CL, and nitric oxide production in cultured lavaged alveolar macrophage cells determined 1 day after exposure. No significant deviation from additivity was found for breathing rate increase and polymorphonuclear leukocytes infiltration. Simultaneous administration of zymosan and LPS or administration of LPS before zymosan did not change these indices of pulmonary responsiveness. These data suggest that the inhibitory effect of 1-->3-beta-glucans on pulmonary responsiveness to endotoxin exposure was apparent only when rats were pretreated with 1-->3-beta-glucan. These results suggest that complex interaction of components may exist in exposure to organic dusts. Therefore, hazard may not be defined by measuring endotoxin or 1-->3-beta-glucans alone.

N- and O-linked oligosaccharides of allergenic glycoproteins

Cross-linking of cell-bound IgE on mast cells or basophils by polyvalent antigens causes the release of histamine and other mediators of the allergic response which then lead to the development of allergic symptoms. In this event not only peptide epitopes, but also carbohydrates can act as cross-linking elements. Since peptide epitopes of allergens are subject of most published studies, this review is focused on glycosidic epitopes. The current knowledge of the structures and possible epitopes of oligosaccharides linked to allergenic glycoproteins is briefly reviewed, showing that complex plant N-glycans containing alpha1,3 fucose and beta1,2 xylose are most frequently involved in the structures of IgE epitopes. In own studies a prevalence of up to 29% anti-glycan IgE was determined among pollen-allergic patients. The clinical relevance of these carbohydrate specific IgE antibodies is still a matter of controversial discussions.

Inhalation of (1-->3)-beta-D-glucan causes airway eosinophilia

BACKGROUND

Moulds are present in a variety of environments and aerosols of fungal spores are generated when mouldy materials are handled. Molds contain (1-->3)-beta-D-glucan, a polyglucose which is present in the cell wall of fungi, certain bacteria and plants.

AIM

This study was undertaken to investigate the cellular inflammatory response in the lung after inhalation of (1-->3)-beta-D-glucan and bacterial endotoxin.

METHODS

Guinea pigs were exposed daily to an aerosol of pure (1-->3)-beta-D-glucan and pure endotoxin for five weeks. Lung lavage and lung interstitial cell preparations were done and the inflammatory cells counted. Histological sections were prepared from the trachea.

RESULTS

There was an increase in eosinophil numbers in lung lavage, lung interstitium, and the airway epithelium of animals exposed to (1-->3)-beta-D-glucan. In animals simultaneously exposed to endotoxin, there was no increase in eosinophils. In the lung interstitium, (1-->3)-beta-D-glucan exposure caused an increase in lymphocytes, which was not found after endotoxin exposure. Endotoxin exposure caused an increase in neutrophils and macrophages in lung lavage, which was not found after (1-->3)-beta-D-glucan exposure.

CONCLUSIONS

The results support previous findings that (1-->3)-beta-D-glucan causes a different response in the airways as compared to endotoxin. Endotoxin modulated the increase in eosinophils caused by (1-->3)-beta-D-glucan exposure, suggesting a complex interaction between the microbial cell wall components.

Alveolar macrophages bind and phagocytose allergen-containing pollen starch granules via C-type lectin and integrin receptors: implications for airway inflammatory disease

Recent studies suggest that IgE-independent mechanisms of airway inflammation contribute significantly to the pathophysiology of allergic airway inflammatory diseases such as asthma. Such mechanisms may involve direct interactions between inhaled allergens and cells of the respiratory tract such as macrophages, dendritic cells, and epithelial cells. In this study, we investigated receptor-mediated interactions occurring between alveolar macrophages and allergen-containing pollen starch granules (PSG). We report here that PSG are released from a range of grass species and are rapidly bound and phagocytosed by alveolar macrophages. Human monocyte-derived dendritic cells also bound PSG but no internalization was observed. Phagocytosis of PSG was dependent on Mg2+ and Ca2+ and was inhibited by neo-glycoproteins such as galactose-BSA and N-acetylgalactose-BSA. Partial inhibition of phagocytosis was also seen with the Arg-Gly-Asp-Ser (RGDS) motif and with an anti-CD18 mAb (OX42). The combination of both neo-glycoprotein and anti-CD18 achieved the greatest degree of inhibition (>90%). Together, these data suggest a role for both C-type lectins and beta2-integrins in the binding and internalization of PSG. The consequences of this interaction included a rapid up-regulation of inducible NO synthase mRNA and subsequent release of NO by alveolar macrophages. Thus, receptor-mediated recognition of inhaled allergenic particles by alveolar macrophages may represent a potential mechanism for modulating the inflammatory response associated with allergic airway diseases such as asthma.