Immunobiological characteristic of grass pollen allergens / Монголын Анагаах Ухаан

Grass pollens are one of the most important airborne allergen sources worldwide. The Poaceaefamily comprises about 9000 species, 20 species from five subfamilies are considered to be the mostfrequent causes of grass pollen allergy, and the allergenic relationships among them closely follow theirphylogenetic relationships. The allergic immune response to pollen of several grass species has beenstudied extensively over more than three decades. Eleven groups of allergens have been identified anddescribed, in most cases from more than one species. The most complete set of allergens has so farbeen isolated and cloned from Phleum pratense (timothy grass) pollen. Based on the prevalence of IgEantibody recognition among grass pollen-sensitized individuals, several allergens qualify as major, butmembers of two groups, groups 1 and 5, have been shown to dominate the immune response to grasspollen extract. Isoform variation has been detected in members of several of the allergen groups, whichin some cases can be linked to observed genetic differences. N-linked glycosylation occurs in membersof at least three groups. Carbohydrate- reactive IgE antibodies have been attributed to grass pollensensitization and found to cross-react with glycan structures from other allergen sources, particularlyvegetable foods. Another cause of extensive cross-reactivity are the group 12 allergens (profilins), whichbelong to a family of proteins highly conserved throughout the plant kingdom and present in all tissues.Members of eight allergen groups have been cloned and expressed as recombinant proteins capableof specific IgE binding. This development now allows diagnostic dissection of the immune response tograss pollen with potential benefits for specific immunotherapy.

IgE cross-reactivity between Lolium multiflorum and commercial grass pollen allergen extracts in Brazilian patients with pollinosis

Lolium multiflorum (Lm) grass pollen is the major cause of pollinosis in Southern Brazil. The objectives of this study were to investigate immunodominant components of Lm pollen allergens and the cross-reactivity of IgE with commercial grass pollen allergen extracts. Thirty-eight serum samples from patients with seasonal allergic rhinitis (SAR), 35 serum samples from patients with perennial allergic rhinitis (PAR) and 30 serum samples from non-atopic subjects were analyzed. Allergen sensitization was evaluated using skin prick test and serum IgE levels against Lm pollen extract were determined by ELISA. Inhibition ELISA and immunoblot were used to evaluate the cross-reactivity of IgE between allergens from Lm and commercial grass pollen extracts, including L. perenne (Lp), grass mix I (GI) and II (GII) extracts. IgE antibodies against Lm were detected in 100 percent of SAR patients and 8.6 percent of PAR patients. Inhibition ELISA demonstrated IgE cross-reactivity between homologous (Lm) and heterologous (Lp or GII) grass pollen extracts, but not for the GI extract. Fifteen IgE-binding Lm components were detected and immunoblot bands of 26, 28-30, and 32-35 kDa showed >90 percent recognition. Lm, Lp and GII extracts significantly inhibited IgE binding to the most immunodominant Lm components, particularly the 55 kDa band. The 26 kDa and 90-114 kDa bands presented the lowest amount of heterologous inhibition. We demonstrated that Lm extract contains both Lm-specific and cross-reactive IgE-binding components and therefore it is suitable for measuring quantitative IgE levels for diagnostic and therapeutic purposes in patients with pollinosis sensitized to Lm grass pollen rather than other phylogenetically related grass pollen extracts.

Construction of humulus scandens pollen major allergen pcDNA3.1-LC2 DNA vaccine and study of its immunogenicity in mice / 西安交通大学学报(医学版)

Objective To construct humulus scandens pollen major allergen DNA vaccine pcDNA-LC2 and evaluate its immunogenicity. Methods Humulus scandens pollen allergen gene was digested from recombinant plasmid pTripIEx2-LC2 by EcoRⅠ and HindⅢ of restriction endonuclease, and then inserted into expression vector pcDNA3.1(-). A large amount of endotoxin pcDNA3.1-LC2 purified plasmid was extracted after successful construction, and animal experiment was carried out to study its immunocompetence. Results Sequencing results showed that 672bp in the coding sequence of frames of recombinant pcDNA3.1-LC2 was in line with the original base line, without deletion or mutation. pcDNA3.1-LC2 of pollen allergen humulus scandens allergen vaccinated BALB/c mice. Double immunodiffusion test showed that pcDNA3.1-LC2 could be expressed and produce antibodies in mice. Conclusion Humulus scandens grass pollen major allergen DNA vaccine pcDNA3.1-LC2 has been successfully constructed. It can be expressed in mice, produces humulus scandens grass pollen allergen specific antibody and has a good immunogenicity.

Classification and evolutionary analysis of pollen allergens / 中华微生物学和免疫学杂志

Objective To classify all the plant pollen allergens, each allergen sequence available was compared with protein family database. After that, the appearance and taxonomic distribution of each protein family could be known. When made reference to evolutionary analysis, a regular rule of the distribu-tion of all plant pollen allergens could be concluded. Methods Protein family memberships of each allergen were assigned by comparing the sequences with the Pfam database. Representative members of the most a-bundant pollen allergen families were compared with the Uniprot database using the BLAST server. Acces-sion number of all the interesting homologous could be obtained and all the sequence information could be ac-quired by Batch Entrez. Finally, the evolutionary trees were drawn with the help of MEGA4.0 software. Re-sults One hundred and sixty-eight pollen allergens were classified into 26 protein families. Profilins, pollen _allerg_1 and EF hands constituted the most abundant pollen allergen families. Profilins and EF hands oc-curred in almost all allergenic plant families, whereas allergenic Expansins, FAD_binding proteins, Amb_V allergens and Thaumatins were confined to single taxon. Conclusion It is concluded that the highly con-served sequences of allergens families such as Profilin may be one of the most important reasons of the cross reactivities in allergic diseases. The classification of pollen allergens may be helpful to clinical practice and basic research.

Partial purification and analysis of major allergenic components of Platanus acerifoli wild pollen allergen / 西安交通大学学报(医学版)

Objective To purify and identif y Platanus acerifoli wild pollen. Methods We carried out intracutaneous test with Platanus pollen extract in 30 patients with allergic as thma who visited our hospital from March to May 2003. Seven subjects who had bee n diagnosed as having Platanus pollen-induced asthma were enrolled. Platanus po llen proteins were separated by gel filtration with Sephadex-G-100. To charact erize allergenic components, Platanus pollen extract was analyzed by means of so dium dodecylsulfate-polyacrylamide gel electrophoresis followed by immunoblotti ng. Results To purity the pollen we separated Platanus poll en extract in a first purification step by using gel filtration with Sephadex G -100. Two elution peaks were observed. Twelve percent SDS-PAGE analysis showed more than 10 protein bands whose molecular mass (Mr) ranged from 16 ku to 71 ku. Six bands abundant with protein at 71, 50, 35, 39, 22 and 16 ku were observed. On SDS-PAGE, the proteins of the first peak whose Mr we re 71, 50, 35, 39, and 22 ku and that of the second peak was 16 ku. SDS-PAGE and IgG-immunoblotting analysis with seven sera showed 4 IgG-binding component s whose Mr was 50, 39, 22 and 16 ku. The protein bands whose Mr was 50 ku and 22 ku had the highest binding capacity. Conclusion The strongest activity exists in the first peak which can be the major sensiti zing components and there is mild allergic activity in the second peak which is the minor sensitizing components.