Detection of allergens in plantain (Plantago lanceolata) pollen
ABSTRACT Allergens in Plantago lanceolata have not been characterized yet. The objective was to characterize some plantain-pollen allergens and to investigate the cross-reactivity between plantain and grass pollens.
Sera from four patients monosensitive to plantain pollen and from eight grass-pollen-allergic patients showing strong skin reactivity to plantain pollen in the skin prick test (SPT) underwent immunoblot analysis with both Plantago and grass mix extract. Moreover, immunoblot inhibition experiments were done with grass mix extract as inhibitor.
All four sera from plantain-allergic patients reacted to two distinct bands at 17 and 19 kDa, and 2/4 sera showed further reactivity to a 40-kDa protein, which in one case represented the most prominent IgE-binding allergen. Plantain-monosensitive subjects did not show any reactivity to grass-pollen extract, and preabsorption of their sera with grass-pollen extract did not cause any loss of reactivity to plantain pollen. Sera from all eight grass-pollen-allergic controls reacted to a 30-kDa protein in plantain pollen, and some sera showed cross-reactivity to higher and lower molecular-weight structures as well. In all cases, plantain reactivity was totally abolished by preabsorption of sera with grass-pollen extract. A preliminary investigation by immunoblot showed that polyclonal IgG anti-Phl p 5 (but not polyclonal Phl p 1) from rabbit reacted to a 30-kDa protein in plantain pollen.
Three specific allergens (of 17, 19, and 40 kDa, respectively) have been detected in plantain pollen. Further studies on a larger number of patients will determine whether these proteins may be considered major allergens. Cross-reactivity between grass and plantain pollen is mainly caused by a 30-kDa protein in plantain pollen. Group 5 grass-pollen allergen is probably responsible for most grass/plantain cross-reactivity.
Full-textDOI: · Available from: Gianni Mistrello, Sep 17, 2014
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ABSTRACT: Seasonal allergic rhinitis is a widespread disorder in westernized countries. It has a strong negative impact on the patient¿s health-related quality of life and is accompanied by considerable medical and economic costs. Currently, the socioeconomic interest in prevention is growing. Reducing or avoiding allergen exposure may result in a significant reduction of sensitization and mitigation of allergic complaints, and this reduction is in addition to existing medical prevention strategies. It will require good communication to (potential) patients on the importance and possibilities for reducing the contact with allergenic pollen. Longterm pollen monitoring and forecasts of the flowering period of allergenic plants are important tools in this respect. Reducing the allergenic load may prove an alternative prevention strategy. Pollen sources are heterogeneously distributed throughout the landscape and may be avoided or selectively removed. The use of selection, conventional breeding strategies or genetic modification may reduce the allergenicity of the pollen sources. Strategies that involve genetic modification are, however, likely to raise some public concern and acceptability of these strategies has to be considered. Keywords: seasonal allergic rhinitis; allergy prevention; pollen allergens; crossreactivity; phenology; allergenicity; risk analysis; public concern
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ABSTRACT: Pla l 1, the major allergen of Plantago lanceolata pollen, is a glycoprotein that contains an N-glycosylation site. Carbohydrate moieties of many allergenic glycoproteins have been reported to be IgE-binding determinants responsible for cross-reactivity among different species. To identify the kind of linkages and the type of glycans present in Pla l 1 and to investigate their contribution to the allergic response to this allergen. Pla l 1 was deglycosylated by N-glycosidase A and the IgE-binding ability of the unglycosylated protein was evaluated by dot-blot. Identification of beta1 --> 2 xylose and/or alpha1 --> 3 fucose residues in Pla l 1 N-glycan was carried out by incubation with specific antibodies from rabbit antiserum against HRP (anti-HRP). The contribution of this N-glycan to total IgE reactivity was analysed quantitatively by pre-incubation of Pla l 1 with anti-HRP prior to incubation with sera. The role of the carbohydrate moiety of Pla l 1 in cross-reactivity was studied by RAST using unrelated glycoproteins with known sugar composition and structure. The effectiveness of N-glycosidase A to deglycosylate Pla l 1 and the ineffectiveness of the treatment with PNGase F indicate that Pla l 1 carries a complex N-glycan with an alpha1 --> 3 fucose residue in its structure. Furthermore, the presence of beta1 --> 2 xylose and/or alpha1 --> 3 fucose residues was identified in this N-glycan by means of an ELISA. Pre-incubation of Pla l 1 with an anti-HRP antibody caused a weak but significant reduction in IgE reactivity. Some sera from P. lanceolata-allergic patients reacted positively with four glycoproteins that bear N-glycans of complex type but not with fetuine. Pla l 1 is a glycoprotein that carries at least a complex, major N-linked glycan, with a alpha1 --> 3 fucose residue in its structure and probably also a beta1 --> 2 xylose. This glycan moiety does not seem to constitute a relevant allergenic epitope of Pla l 1.Clinical & Experimental Allergy 11/2002; 32(11):1628-34. DOI:10.1046/j.1365-2222.2002.01530.x · 4.32 Impact Factor
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ABSTRACT: The effects of sudden and massive exposure of the general population to novel airborne allergens are not known. This study aimed to investigate the clinical effects of two "new" allergens, ragweed and birch, in an area north of Milan during the last 15 years. We reviewed the records of 2571 monosensitized patients seen during the last 10 years in two allergy units north of Milan. Data included age at onset of allergic symptoms, and family history of allergic diseases. In this sample, 500 were allergic to grass, mite, birch, and ragweed; 293 to pellitory; 167 to mugwort; 100 to Alternaria; and 11 to plantain. Birch pollen-allergic patients and ragweed pollen-allergic patients showed a similar mean age at onset (35.3 years vs. 35.1 years; P = NS), but were significantly older than all other groups of patients (P < 0.001). Patients allergic to ragweed and birch pollen, 304 and 323 respectively, were >30 years at the onset of allergic symptoms. A family history of allergic disorders among first degree relatives was far less frequent among patients allergic to birch pollen (29%) or ragweed pollen (27%) than among patients sensitive to all other airborne allergens, except those allergic to mugwort pollen (P < 0.001). In both ragweed and birch groups, a positive family history was significantly more common among subjects < 30 years than in those > 30 years at onset of respiratory allergy (81/196 (41%) vs. 54/304 (18%), P < 0.001 for the ragweed group; 80/177 [45%]vs. 65/323 (20%), P < 0.001 for the birch group). Exposure of the general population of this area to two new airborne allergens resulted in the onset of respiratory allergy in many older people who lacked any relevant predisposing factor. Although we cannot exclude the possibility that those who became allergic had been exposed to birch or ragweed pollen elsewhere, a more likely explanation is a specific susceptibility that remains viable until the subject encounters the "right" allergen.Allergy 11/2002; 57(11):1063-6. DOI:10.1034/j.1398-9995.2002.23766.x · 6.00 Impact Factor