Birch Profilin Research Articles

Analysis of maize profilin-4 isoform as an allergen

Profilin is an actin monomer-binding protein that controls the dynamic turnover of actin filaments and is ubiquitously present in different organisms ranging from prokaryotes to higher eukaryotes. Maize (Zea mays) profilin-4 isoform is a pollen-specific protein. Birch profilin isoform is a known allergen but maize profilin is yet to be characterized. Due to the high cultivation rate of maize, the analysis of the properties of maize profilin-4 isoform as an allergen is a demand of time for developing an effective immune therapy. Here, we analyzed the allergenic potency of profilin-4 by studying of its physicochemical properties, including molecular weight (~14kD) and theoretical pI (4.63). We tested the potential B cell epitope candidates of profilin-4 using different immune-informatics tools housed at IEDB analysis resource. For the B cell epitope prediction, potential antigenic sites on the protein surface were predicted by both propensity scale and machine learning method followed by their mapping of 3D structure prediction. We hereby claim that the profilin-4 is a potential allergen and is able to induce allergic responses. However, the wet lab experiments are needed to validate our claim that is beyond our scope.

Detection of the tomato allergen Sola l 1 and evaluation of its reactivity after heat and papain treatment

ABSTRACTTo detect the tomato allergen profilin (Sola l 1) from fresh tomato and tomato-containing processed foods, we generated a rabbit polyclonal anti-Sola l 1 peptide antibody. An indirect enzyme-linked immunosorbent assay (iELISA) based on the antibody was established for semiquantification of Sola l 1, and standard curves were generated using Sola l 1 homologue recombinant birch profilin (rBet v 2) as a calibrator. The mean concentration of tomato extracts was 25.6 ± 9.1 µg/g, and the concentrations of tomato-containing processed foods ranged from 13.3 to 24.8 µg/g. The reactivity of Sola l 1 after heat and papain treatment of tomato extracts was evaluated using competitive iELISA, and the results showed that Sola l 1 reactivity was stable with or without treatment. Our findings suggested that tomato-containing processed foods and fresh tomatoes both contained Sola l 1 and could have the potential to induce allergic symptoms in patients with tomato allergies.

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.

Bet v 2 Responsibility in Birch-Induced Symptoms

We report the case of a patient who first had grass pollinosis associated to food allergy, especially melon, and who developed secondarily early spring pollinosis which could be related to sensitization to the birch profilin. This patient, whose birch pollinosis was confirmed by nasal provocation test, was not sensitized to Bet v 1, the major birch pollen allergen in North Western Europe. We demonstrated by inhibition studies using grass and birch profilins that the clinical birch allergy was induced by the cross reacting profilin present both in birch and grass pollen and also in melon.

Component-resolved diagnosis of peach allergy and its relationship with prevalent allergenic pollens in China

Component-resolved diagnosis of peach allergy and its relationship with prevalent allergenic pollens in China

Proteomic profiling of birch (Betula verrucosa) pollen extracts from different origins

Pollen of the European white birch is a major source of spring pollinosis in Europe. Pollen-allergy diagnosis and treatment by specific immunotherapy commonly rely on extracts of natural origin. To gain insight into the protein content and its variability, we evaluated the profile of allergenic and non-allergenic proteins in extracts of pollen from different origins by MS-based proteomics. Aqueous extracts prepared from commercially available Swedish birch pollen, pollen collected from Austrian trees and a commercial skin prick extract were analyzed by 1-DE, 2-DE, immunoblotting and mass spectrometry, resulting in a complete inventory of extractable, disease-relevant pollen proteins. A main focus of this study was on the isoform distribution of Bet v 1, the major allergen of birch pollen. Using a combination of intact mass determination and peptide sequencing, five isoforms (a, b, d, f and j) were unequivocally identified in Swedish and Austrian birch pollen extracts, while the skin prick extract contained only isoforms a, b and d. Using the same methods as for Bet v 1, divergencies in the sequence of birch profilin (Bet v 2), a plant panallergen, were solved. The molecular characterization of pollen extracts is relevant for standardization and development of new reagents for specific immunotherapy.

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

Patients with birch pollen allergy often develop allergic reactions to plant foods. 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. 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. 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. 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.

Cloning of the panallergen profilin from lychee fruit and its cross-reactivity with birch pollen profilin Bet v 2

Lychee fruits can cause severe anaphylactic reactions and has cross-reactivity with other allergens. Panallergen profilin is partly responsible for the cross-reactivity between allergens. In the present study, the cDNA of lychee profilin was performed by RT-PCR and 3′RACE from total RNA. The lychee profilin cDNA includes an open reading frame coding for 131 amino acids. The deduced amino acid sequence of the corresponding protein show high identity with other allergenic profilins. Expression of the recombinant lychee profilin was carried out in Escherichia coli BL21 (DE3) using vector PET-28a, and the purification of the recombinant protein was performed via affinity chromatography with Ni+ coupled to sepharose. IgE reactivity of recombinant lychee profilin was investigated by immunoblot, and five of 15 lychee-allergic patients tested presented specific IgE antibodies to recombinant lychee profilin. IgE inhibition and ELISA inhibition experiments were performed to analyze lychee profilin cross-reactivity with profilins from birch pollen, and a high cross-reactivity between lychee profilin and birch profilin has been found in sera from lychee allergic patients.

Mango profilin: cloning, expression and cross-reactivity with birch pollen profilin Bet v 2

Mango can cause severe anaphylactic reactions. Profilin has been assumed partly responsible for the cross-reactivity between mango fruit and other allergens but has not been finally clarified. In this study, two isoforms of mango fruits profilin were amplified by RT-PCR and 3'RACE from total RNA. Each mango profilin cDNA includes an open reading frame coding for 131 amino acids. The deduced amino acid sequence of the corresponding protein show high identity with other allergenic profilins. Expression of the recombinant mango profilin was carried out in Escherichia coli BL21(DE3) using vector PET28a and the purification of the recombinant protein was performed via affinity chromatography with Ni+ coupled to sepharose. IgE reactivity of recombinant mango profilin was investigated by immunoblot and 8 of 18 mango-allergic patients tested presented specific IgE-antibodies to recombinant mango profilin. IgE-inhibition and ELISA inhibition experiments were performed to analyze mango profilin cross-reactivity with profilins from birch pollen and high cross-reactivities have been found.

T-Cell Receptor-Mediated Cross-Allergenicity

Background: Profilins are conserved and ubiquitous plant and animal proteins. We wanted to discover whether the T-cell response to conserved epitopes on birch and grass profilins could account for cross-allergenicity in subjects allergic to these two pollens. Methods: Thirty-one patients allergic to grass and birch were recruited for the study. Grass and birch reactive T lymphocytes were studied by measuring proliferation to birch and grass allergen, respectively, followed by Vβ T-cell receptor family-specific polymerase chain reaction and heteroduplex analysis. T-cell clones were derived from patients with cross-proliferating T cells. Results: In 25 of 31 subjects the T-cell response to grass was quite distinct from that to birch. In contrast, in 6 of 31 individuals grass T cells cross-proliferated to birch and this was reproduced in 4 patients by birch profilin. CD4 Th2 cell clones were derived which promiscuously recognized homologously conserved regions on birch and grass profilins. Conclusion: We conclude that a functionally relevant T-cell response to conserved regions of panallergens underlie cross-allergenicity in a subset of allergic patients. These results suggest that a reciprocal modulation of the response to one sensitizing allergen can occur following natural exposure to or immunotherapy with another allergen. These results have relevance in the management of patients with multiple allergies.

Identification of Oilseed Rape (Brassica napus) Pollen Profilin as a Cross-Reactive Allergen

Background: Major allergens of oilseed rape (OSR) pollen with molecular weights of 6/8, 14 and between 27 and 69 kD have been described. The aim of the present study was to further characterize the 14-kD allergen. Methods: The 14-kD protein was purified from OSR pollen extracts by poly-(L-proline) (PLP)-Sepharose affinity chromatography and characterized immunologically by means of allergic patients’ IgE antibodies, profilin-specific rabbit antisera, Western blot and ELISA inhibition using recombinant birch profilin (rBet v 2), and skin prick testing. Results: By PLP affinity chromatography, OSR pollen profilin was purified as a single protein of 14.5 kD and further identified as a profilin by three polyclonal rabbit antisera raised against ragweed and tobacco pollen profilin and the C-terminus of birch profilin. IgE binding of a human serum pool (n = 15) and four profilin-reactive sera to nitrocellulose-blotted OSR profilin was completely inhibited by 1 µg/ml rBet v 2 (birch profilin). Reciprocal ELISA inhibition using increasing concentrations of rBet v 2 and purified OSR profilin, respectively, showed that rBet v 2 strongly inhibits antibody binding to OSR profilin, whereas almost 100 times the amount of OSR profilin was needed to inhibit IgE binding to rBet v 2. Skin prick tests were positive (wheal ≧3 mm) with 5 µg/ml rBet v 2 in all three patients tested, and with OSR profilin in two patients at a concentration of 50 µg/ml. Conclusions: OSR pollen profilin shares IgE and IgG epitopes with Bet v 2 and other plant profilins and may represent a potentially relevant allergen for profilin-sensitized patients.

Clinically relevant peach allergy is related to peach lipid transfer protein, Pru p 3, in the spanish population

Background Sensitization to peach and related Rosaceae fruits without clinical expression is commonly observed as the result of the extensive cross-reactivity of IgE antibodies directed toward lipid transfer proteins (LTPs), Bet v 1 homologues, profilins, and carbohydrate determinants. Objective We aimed to study whether there are any clinical or immunologic differences between patients allergic to peach and those who have a current clinically irrelevant sensitization to this fruit. Methods One hundred subjects with adverse reactions to peach were evaluated by medical history, skin prick tests with fresh peach and purified peach LTP (Pru p 3), and specific IgE determinations to peach, rBet v 1, and rBet v 2 (birch profilin). Clinical reactivity to peach was established by double-blind, placebo-controlled food challenges. The clinical characteristics and the in vivo and in vitro tests were compared between allergic and nonallergic patients. Results Peach allergy was confirmed in 76 patients and ruled out in 16; 2 patients dropped out, and the study was not conclusive in 6 individuals (placebo reactors). Pollen allergy was found in 76% of the allergic patients and in 100% of the nonallergic patients. Positive responses to Pru p 3, rBet v 1, and rBet v 2 were observed in 62%, 7%, and 34% of patients allergic to peach, respectively. The sensitization rate to Pru p 3 was significantly higher among subjects allergic than nonallergic to peach (62% vs 31%, P = .02). IgE responses to rBet v 2 were more frequent among subjects allergic to pollen, but no difference was observed in the presence or absence of peach allergy. Conclusions Pru p 3 is the major allergen of peach in our population, and the IgE response to this allergen is related to the clinical expression of peach allergy. Sensitization to profilin is observed in those patients with an associated pollen allergy but does not appear to be related to the clinical reactivity to peach.

Mast cell alpha-chymase reduces IgE recognition of birch pollen profilin by cleaving antibody-binding epitopes.

In sensitized individuals birch pollen induces an allergic response characterized by IgE-dependent mast cell degranulation of mediators, such as alpha-chymase and other serine proteases. In birch and other plant pollens, a major allergen is profilin. In mammals, profilin homologues are found in an intracellular form bound to cytoskeletal or cytosolic proteins or in a secreted form that may initiate signal transduction. IgE specific to birch profilin also binds human profilin I. This cross-reactivity between airborne and endogenous proteins may help to sustain allergy symptoms. The current work demonstrates that cultured mast cells constitutively secrete profilin I, which is susceptible to degranulation-dependent proteolysis. Coincubation of chymase-rich BR mastocytoma cells with Ala-Ala-Pro-Phe-chloromethylketone (a chymase inhibitor) blocks profilin cleavage, which does not occur in degranulated HMC-1 mast cells, which are rich in tryptase, but chymase deficient. These data implicate chymase as the serine protease cleaving secreted mast cell profilin. Sequencing of chymase-cleaved profilins reveals hydrolysis at Tyr(6)-Val(7) and Trp(35)-Ala(36) in birch profilin and at Trp(32)-Ala(33) in human profilin, with all sites lying within IgE-reactive epitopes. IgE immunoblotting studies with sera from birch pollen-allergic individuals demonstrate that cleavage by chymase attenuates binding of birch profilin to IgE. Thus, destruction of IgE-binding epitopes by exocytosed chymase may limit further mast cell activation by this class of common plant allergens, thereby limiting the allergic responses in sensitized individuals.

Profilin is localized in the nucleus-associated microtubule and actin system and is evenly distributed in the cytoplasm of the green algaMicrasterias denticulata

Profilin is detected by means of immunoblotting in the green algaMicrasterias denticulata at a molecular mass of about 14 kDa with antibodies against celery root profilin, recombinant tobacco profilin, and recombinant birch profilin. Poly-L-proline purification ofM. denticulata extracts leads to a single band at 14 kDa. By means of immunoelectron microscopy first evidence is provided for the presence of profilin in a microtubule center associated with the migrating nucleus in high-pressure-frozen and freeze-substituted cells. Colocalization with a particular filamen-tous-actin aggregation in the same area suggests a role of profilin in the process of nuclear migration. Moreover staining is visible in several areas of the nucleus including the nucleolus, heterochromatin, and nuclear-pore complexes. An even distribution of profilin is found throughout the cytoplasm at the confocal-microscopy level as well as by immunogold labeling. Occasionally also areas at the surface of the chloroplast are stained.

PCR-based cloning, isolation, and IgE-binding properties of recombinant latex profilin (rHev b 8).

Profilin (Hev b 8) in natural rubber latex (NRL) has been assumed to be an important allergen. Since latex profilin has a molecular mass similar to two other latex allergens (Hev b 1 and Hev b 6.03) in the 14-kDa range, it is difficult to obtain sufficient amounts of purified native profilin for investigations and diagnostics. The present study aimed to produce recombinant latex profilin (rHev b 8) and study its IgE-binding reactivity. A profilin-specific cDNA encoding the latex profilin from Hevea brasiliensis leaves was synthesized and subcloned, and the rHev b 8 was overexpressed in fusion with the maltose-binding protein (MBP) in E. coli. The IgE-binding reactivity of rHev b 8 was studied by immunoblotting, immunoblot inhibition experiments, and the Pharmacia CAP method, with 25 sera from health-care workers with latex allergy and 17 sera from latex-sensitive spina bifida patients. rHev b 8 was found to have 131 amino acids and a sequence identity of 75% with birch profilin (Bet v 2). Analysis by the CAP system revealed the presence of rHev b 8-specific IgE antibodies in two out of 17 sera from spina bifida patients and in five out of 25 sera (20%) from health-care workers. Two subjects of the latter group with rHev b 8-specific IgE showed negative results in the skin prick tests with tree-pollen extracts and had no IgE to rBet v 2, indicating the presence of IgE-binding epitopes on the Hev b 8-molecule which do not cross-react with birch profilin. Immunoblot inhibition assays using MBP-rHev b 8 as inhibitor confirmed the presence of latex profilin in the NRL extract. IgE binding to the native latex profilin could be completely inhibited by the MBP-rHev b 8. Latex profilin represents a minor allergen in NRL and may have IgE-binding epitopes different from Bet v 2.

IgE binding of the recombinant allergen soybean profilin (rGly m 3) is mediated by conformational epitopes

Background: Soybean proteins are constituents of a number of food products and represent a panel of potential allergens. Thus far, little is known about the molecular characteristics of soybean allergens. Objective: The aim of this study was to identify the soybean profilin by PCR-based complementary (c)DNA cloning and to elucidate its allergenic characteristics. Methods: Highly degenerate profilin-specific primers were used to identify, by means of PCR, 2 soybean profilin isoforms (GmPRO1 and GmPRO2) by using soybean cDNA as a target. One isoform (GmPRO1) with a length of 394 bp corresponding to 131 amino acid residues was subcloned and expressed in fusion with the maltose-binding protein. Moreover, 3 overlapping recombinant soybean profilin fragments comprising amino acid residues 1-65, 38-88, and 50-131 were also prepared as maltose-binding protein fusion proteins. IgE-binding reactivity of the recombinant proteins and the cross-reactivity of soybean profilin with birch profilin was studied by immunoblotting, enzyme-linked allergosorbent assays (EASTs), and competitive inhibition experiments by using serum samples from 13 soybean-sensitized subjects. Results: Results of immunoblot analysis, EAST, and EAST-inhibition experiments indicate the presence of profilin in soybean extract. The recombinant soybean profilin (rGly m 3) was recognized by IgE in 9 (69%) of the 13 sera tested. Only the full-length rGly m 3 was able to bind with IgE antibodies, whereas the 3 soybean profilin fragments did not show significant binding reactivity, indicating that the IgE binding to rGly m 3 depends on the integrity of a conformational structure, which was not present in the overlapping profilin fragments. The rGly m 3 cross-reacted with birch pollen profilin (Bet v 2), and the IgE binding to Bet v 2 could be inhibited by rGly m 3. Conclusions: rGly m 3 represents a new soybean allergen with well-characterized primary sequence, and its IgE-binding reactivity is mediated by conformational epitopes. (J Allergy Clin Immunol 1999;1293-1301.)

Recombinant birch pollen allergens (rBet v 1 and rBet v 2) contain most of the IgE epitopes present in birch, alder, hornbeam, hazel, and oak pollen: A quantitative IgE inhibition study with sera from different populations

Background: Pollen from trees of the order Fagales are important allergen sources in most parts of the world. Clinical, immunochemical, and molecular biology studies indicate that they contain cross-reactive allergens. The major birch pollen allergen, Bet v 1, and birch profilin, Bet v 2, a highly cross-reactive allergen, have been cloned and expressed in Escherichia coli. Objective: The purpose of this study was to demonstrate the presence of allergens in Fagales pollens that share IgE epitopes with recombinant Bet v 1 and Bet v 2 and to determine the percentage of birch, alder, hornbeam, hazel, and oak pollen–specific IgE that can be preabsorbed with rBet v 1 and rBet v 2 from 102 sera of different populations of subjects allergic to Fagales tree pollen. Methods: The presence of rBet v 1– and rBet v 2–homologous allergens in tree pollen extracts was investigated by IgE immunoblot inhibition experiments, and the percentage of tree (birch, alder, hornbeam, hazel, and oak) pollen–specific IgE that was bound by a mixture of rBet v 1 and rBet v 2 was determined by RAST-based quantitative IgE inhibition experiments. The clinical significance of IgE antibody cross-reactivity was studied by skin prick testing with rBet v 1, rBet v 2, and Fagales pollen extracts. Results: Natural birch, alder, hornbeam, hazel, and oak pollen contain allergens that share IgE epitopes with rBet v 1 and rBet v 2. A combination of rBet v 1 and rBet v 2 accounted for 82% of tree pollen–specific IgE on average. Most of the tree pollen–specific IgE was directed against rBet v 1. Conclusion: rBet v 1 and rBet v 2 contain most of the Fagales pollen–specific IgE epitopes and may therefore substitute natural tree pollen extracts not only for diagnosis but also for patient-tailored immunotherapy of tree pollen allergy. (J Allergy Clin Immunol 1998;102:579-91.)

A mimotope defined by phage display inhibits IgE binding to the plant panallergen profilin.

Birch pollen and mugwort pollen allergies are often associated with hypersensitivity to plant foods. This clinical and serological cross-reactivity is mediated by IgE antibodies reacting with homologous proteins in pollen and food. Cross-reacting homologs of the important birch pollen allergen Bet v 2 (profilin) could be detected in other pollen, fruits, nuts, and vegetables, such as celery tuber. We purified IgG/IgE antibodies from the serum of an exclusively profilin-allergic patient using affinity columns either coupled with protein extracts from mugwort pollen, birch pollen, or celery tuber. Constrained and unconstrained random nonapeptide libraries were pooled and screened with the anti-profilin antibody preparations to define cross-reactive ligands. Specific ligands were enriched by successive panning rounds using the profilin-specific antibodies in series. After the last panning round enriched phage clones were screened with purified profilin-specific antibodies and IgE-binding clones were sequenced. Five out of eight positive clones (62.5 %) displayed the same circular peptide CAISGGYPVC. This peptide was synthesized and examined for its ability to inhibit IgE binding to blotted mugwort pollen, birch pollen, or celery tuber profilin. Inhibition studies showed reduction of IgE binding to profilins in all three protein extracts. As the sequence of the mimotope did not show any homology to the known birch profilin sequence this peptide is considered to mimic a common conformational IgE epitope for these examined profilins.

Plant profilin induces actin polymerization from actin:β-thymosin complexes and competes directly with β-thymosins and with negative co-operativity with DNase I for binding to actin

Recombinant plant (birch) profilin was analyzed for its ability to promote actin polymerization from the actin:thymosin β 4 and β 9 complex. Depending on the nature of the divalent cation, recombinant plant (birch) profilin exhibited two different modes of interaction with actin, like mammalian profilin. In the presence of magnesium ions birch profilin promoted the polymerization of actin from A:Tβ 4. In contrast, in the presence of calcium but absence of magnesium ions birch profilin was unable to initiate the polymerization of actin from the complex with Tβ 4. However, under these conditions profilin formed a stable stoichiometric complex with skeletal muscle α-actin, as verified by its ability to increase the critical concentration of actin polymerization. Chemical cross-linking indicated that birch profilin competes with Tβ 4 for actin binding. Ternary complex formation of birch profilin with actin:DNase I complex was suggested by chemical cross-linking. However, the determination of the critical concentrations of actin polymerization in the simultaneous presence of birch profilin and DNase I indicated that profilin and DNase I did not form a ternary complex. These data indicated a negative co-operativity between the profilin and DNase I binding sites on actin.

Identification of common allergenic structures in mugwort and ragweed pollen

Background: Despite the rare occurrence of ragweed in Middle Europe, a surprisingly high number of patients allergic to mugwort, a frequently encountered weed, display IgE reactivity against ragweed pollen allergens. Objective: The aim of this study was to investigate whether the high prevalence of IgE reactivity against ragweed in patients allergic to mugwort is caused by the presence of common allergenic determinants. We also sought to characterize any cross-reactive allergens. Methods: Common allergenic structures in mugwort and ragweed pollen were characterized by qualitative IgE immunoblot inhibition experiments performed with natural allergen extracts and recombinant allergens. The degree of cross-reactivity was estimated by quantitative CAP-FEIA competitions. The clinical significance of cross-reactive IgE antibodies was studied with histamine release experiments and nasal provocation tests. Results: Mugwort and ragweed RAST values were significantly correlated in a population of 82 Austrian patients allergic to mugwort. IgE antibodies cross-reacted with allergens of comparable molecular weight that were present in both extracts. By using recombinant birch profilin and specific antisera for IgE inhibition experiments, profilin was identified as one of the cross-reactive components in mugwort and ragweed pollen. Preincubation of sera from patients allergic to mugwort with mugwort extract inhibited IgE binding to ragweed pollen extract greater than 80%. Mugwort and ragweed pollen extract induced comparable histamine release and reduction of nasal air flow in a patient with IgE reactivity against the major mugwort allergen Art v 1. Conclusion: In addition to profilin, mugwort and ragweed pollen contain a number of cross-reactive allergens, among them the major mugwort allergen Art v 1. Cross-reactive IgE antibodies can lead to clinically significant allergic reactions. (J Allergy Clin Immunol 1998;101:196-206.)