Differential expression and sequence polymorphism of the olive pollen allergen Ole e 1 in two Iranian cultivars.

Molecular evidence on the heterogeneity present in the Ole e 1 allergen of the olive pollen is emerging. Such polymorphism is dependent on the cultivar origin of pollen, which also determines wide differences in the expression of this protein. Determination of biochemical and molecular characteristics of Ole e 1 pollen allergen in two Iranian olive cultivars, namely 'Rowghani' and 'Zard' is necessary to assess their allergenicity potential. SDS-PAGE and immunoblotting analysis of pollen extracts showed that both cultivars present high and low expression of Ole e 1, respectively. These protein levels correlated with similarly different levels of transcripts, as determined by RT-PCR. Two-dimensional protein profiles also showed conspicuous differences in the distribution and the level of expression of those spots reacting to an anti-Ole e 1 antibody. Bioinformatic analysis of four Ole e 1 sequences corresponding to 'Rowghani' and two sequences for 'Zard', showed numerous heterogeneities when compared with those Ole e 1 and Ole e 1-like sequences present in databases. Nucleotide substitutions resulted in many cases in changes over the predicted amino acid sequences. A cladistic analysis of the sequences showed Iranian entries in a central position between West-European sequences, and Ole e 1-like sequences from other Oleaceae species. Moreover, amino acid changes affected key epitopes of the protein involved in the recognition of the protein by the human immune system. Putative implications of polymorphism in both the biological role and the allergic reactivity of Ole e 1 are discussed.

Birch pollen-related food allergy: clinical aspects and the role of allergen-specific IgE and IgG4 antibodies.

BACKGROUND: Patients with birch pollen allergy often develop allergic reactions to plant foods. OBJECTIVE: To evaluate the prevalence, main symptoms, and triggers of birch pollen-related food allergy and the role of food-specific IgG(4) antibodies in food tolerance. METHODS: Food-induced symptoms were evaluated in 225 individuals with birch pollen allergy by using a standardized questionnaire. IgE and IgG(4) levels specific for the major birch pollen allergen Bet v 1 and birch profilin Bet v 2 and the Bet v 1 homologs in apple (Mal d 1) and hazelnut (Cor a 1) were quantified by ImmunoCAP. Mock-treated and IgG-depleted sera from patients tolerating hazelnuts in food challenges were compared for their inhibitory activity for binding of Cor a 1-IgE complexes to B cells. RESULTS: In total, 73% of the study population experienced food allergy, which was perennial in 86% of the affected individuals. The oral allergy syndrome was the main clinical manifestation. However, more than 58% of the patients also experienced food-induced rhinoconjunctivitis. Apples and hazelnuts were identified as the most frequent triggers. Food allergy correlated with IgE reactivity to Bet v 1 but not to Bet v 2. Mal d 1-specific and Cor a 1-specific IgG(4)/IgE ratios were significantly higher in food-tolerant individuals than individuals with food allergy. Sera from IgG(4)-positive food-tolerant patients possessed IgG-dependent IgE-inhibitory activity. CONCLUSION: Birch pollen-related food allergy is highly prevalent and often perennial. High food allergen-specific IgG(4)/IgE ratios seem associated with food tolerance, potentially because specific IgG(4) blocks IgE binding to food allergens. Thus, the presence of food allergen-specific IgG(4) antibodies is no diagnostic marker for birch pollen-related food allergy.

Pollen aeroallergens in the Washington, DC, metropolitan area: a 10-year volumetric survey (1998-2007).

BACKGROUND: Local aeroallergen surveys identify and establish patterns of prevalence for tree, grass, and weed species that enable the clinician to more effectively select allergens for skin testing and therapy. OBJECTIVES: To determine peak pollination periods, atmospheric concentrations, and year-to-year variation for identified tree, weed, and grass aeroallergens and examine the influence of selected meteorological parameters. METHODS: Atmospheric sampling for pollen aeroallergens was performed using a volumetric rotating-arm impaction sampler. The Spearman correlation coefficient was used to determine the relationship between daily counts and selected meteorological parameters. RESULTS: Previous findings for area trees, conducted at a different location, are corroborated. Predominant pollen types include Quercus, Cupressaceae, Pinaceae, Morus, Betulaceae, Acer, Platanus, Fraxinus, Poaceae, and Ambrosia. Early flowering weeds (Rumex and Typha) and Poaceae overlap with peak tree season in April. Biphasic seasons are noted for Poaceae and Ulmus. Tree pollen accounts for 91.2%, weeds 3.8%, and grasses 3.2% of total annual pollen yield. Variation in overall pollen production is evident from year to year. High production years for some species are low for others. Cyclic pollinating patterns for Alnus, Betulaceae, and Fagus were observed. Grass and weed pollen correlated positively with maximum temperature and dew point; however, the results for individual tree species were variable. CONCLUSION: The Washington, DC, metropolitan area is host to a variety of tree, weed, and grass species that produce copious amounts of pollen. Further investigation into year-to-year variation with respect to inherent cycling and meteorological influences is warranted.

The principle of homologous groups in regulatory affairs of allergen products--a proposal.

Among other legal regulations, the Note for Guidance on Allergen Products CPMP/BWP/243/96 released by the European Medicines Agency provides regulatory instructions regarding the quality of allergen extracts for diagnostic or therapeutic purposes. The current revision of this guideline intends to transform the so-called 'principle of taxonomic families' to the 'principle of homologous groups'. According to this concept, the data of one allergen extract demonstrating stability, efficacy and safety can, to a limited extent, be extrapolated to other allergen extracts belonging to the same homologous groups. The present work proposes the formation of homologous groups for pollen species and animal-derived materials on the basis of similar biochemical composition and homology/cross-reactivity of allergens or allergen sources. Some tree pollen species could be assigned to three different homologous groups, some weed pollen species to one homologous group and numerous grass pollen species to one homologous group on condition that data rely on single defined representative species. A homologous group for mites is limited to the Dermatophagoides species and the grouping of vertebrate-derived materials such as dander could be possible under restrictions. The criteria for the formation of the proposed homologous groups are illustrated in detail to provide an opportunity for extending existing homologous groups by further species in case of new insights in allergens and cross-reactivity of allergen sources. In this way, the concept of homologous groups could serve as a dynamic tool in the regulation of allergen products.

Recent proliferation and translocation of pollen group 1 allergen genes in the maize genome.

The dominant allergenic components of grass pollen are known by immunologists as group 1 allergens. These constitute a set of closely related proteins from the beta-expansin family and have been shown to have cell wall-loosening activity. Group 1 allergens may facilitate the penetration of pollen tubes through the grass stigma and style. In maize (Zea mays), group 1 allergens are divided into two classes, A and B. We have identified 15 genes encoding group 1 allergens in maize, 11 genes in class A and four genes in class B, as well as seven pseudogenes. The genes in class A can be divided by sequence relatedness into two complexes, whereas the genes in class B constitute a single complex. Most of the genes identified are represented in pollen-specific expressed sequence tag libraries and are under purifying selection, despite the presence of multiple copies that are nearly identical. Group 1 allergen genes are clustered in at least six different genomic locations. The single class B location and one of the class A locations show synteny with the rice (Oryza sativa) regions where orthologous genes are found. Both classes are expressed at high levels in mature pollen but at low levels in immature flowers. The set of genes encoding maize group 1 allergens is more complex than originally anticipated. If this situation is common in grasses, it may account for the large number of protein variants, or group 1 isoallergens, identified previously in turf grass pollen by immunologists.

Localization of group-1 allergen Zea m 1 in the coat and wall of maize pollen.

The pollen surface consists of an outermost coat and an underlying wall. It makes the initial contact with the stigma surface during sexual reproduction. To date, only two proteins have been identified from the maize pollen coat. Zea m 1 (beta-expansin 1) is the major group-1 allergen in maize pollen, but its presence and localization in the pollen coat and wall has not yet been explored. In the present study, immunoblot analysis using an antibody directed against group-1 allergen revealed that a small amount of Zea m 1 exists in the pollen coat fraction prepared using a diethyl ether wash. Immunogold labeling also showed that the extracellular localization of Zea m 1 was mainly restricted to the tectum and the foot layer of the exine (the outer pollen wall), and gold particles immunolabelling Zea m 1 were unevenly dispersed throughout the pollen coat and wall. Moreover, a substantial amount of Zea m 1 was localized in the cytoplasm of the pollen interior. The presence of Zea m 1 in the pollen coat and wall suggests that Zea m 1 may play a potential role in pollen germination on the stigma.

Differences in the spatial distribution of airborne pollen concentrations at different urban locations within a city.

BACKGROUND: The objective of the present work was to compare pollen counts at three different urban locations within a city to each other and to the counts from a fixed trap. This information could be useful to delimit zones in the urbanized part of the city according to the risk of allergic affections. METHODS: Aerobiological sampling using portable traps was carried out at three points in urban zones of the city of Badajoz (SW Spain) over one year at the same time as continuous sampling using a fixed trap at a point in the nonurban outskirts of the city. The sources of airborne pollen were studied by counting the trees in the streets and squares of the selected zones. A statistical analysis was performed of the differences between the portable and fixed traps and of the temporal and spatial variation in the city as a function of the distribution of the most important pollen sources. RESULTS: Forty-eight pollen types were identified with the fixed trap, and 28 with the portable traps. The grass, olive, and oak pollens come from almost exclusively external sources, there being no spatial differences in their concentrations in the city. Cypress pollen concentrations were much higher at the urban locations than at the fixed trap site. Plane tree pollen levels could be locally very high, reflecting the proximity of the source. Except for ornamental plants, pollen levels were lower at the urban locations than at the site on the outskirts of the city. CONCLUSIONS: (1) Using portable traps at different urban zones in a city could provide information about the spatial variation of atmospheric pollen levels. (2) A knowledge of the often widely variable distribution of ornamental plants with potentially allergenic pollen could be useful in indicating city zones with a greater or lesser incidence of potential pollinosis.

Clinico-immunologic evaluation of allergy to Himalayan tree pollen in atopic subjects in India--a new record.

Exposure to local pollen allergens has a direct bearing on the prevalence of allergic symptoms among the inhabiting atopic population. The populations in the Himalayas and around it are exposed to a variety of pollen grains from trees growing in the region, but the pollen-population interaction has not been clinically investigated. Himalayan tree pollen from five different taxa, i.e. Alnus nitida (AN), Betula utilis (BU), Cedrus deodara (CD), Mallotus phillipensis (MP) and Quercus incana (QI) were evaluated for their allergenicity in the Indian population by in vivo (skin prick test) and in vitro (ELISA) clinico-immunological methods. The presence of specific IgE against these tree pollen in the sera of skin test positive patients was taken as evidence for sensitization to these pollen. The average skin positivity in atopic populations recorded at different allergy centers in India varied from 2.2% against AN, to 4.7% against MP pollen. Significantly raised specific IgE against these pollen were observed in the sera of hypersensitive patients. The sensitization pattern to Himalayan tree pollen in these atopic populations varied. It was concluded that skin prick test positivity and raised IgE antibodies specific to AN, BU, CD, MP and QI established Himalayan tree pollen as important sensitizers in the atopic populations of India. A high incidence of skin sensitivity was observed to pollen antigens of Cedrus deodara, Mallotus phillipensis and Quercus incana in patients of Chandigarh residing in the hills and foothills of the Himalayas while Alnus nitida, Betula utilis and Cedrus deodara were important sensitizers in Delhi patients. The skin sensitization pattern against these pollen was in accordance with the level of exposure to these pollen of the subjects residing in that part of the country.