title: Recombinant pollen allergens from Dactylis glomerata: preliminary evidence that human IgE cross-reactivity between Dac g II and Lol p I/II is increased following grass pollen immunotherapy.
abstract: We previously described the isolation of three identical complementary DNA (cDNA) clones, constructed from Orchard/Cocksfoot grass (Dactylis glomerata) anther messenger RNA (mRNA), expressing a 140,000 MW beta-galactosidase fusion protein recognized by IgE antibodies in atopic sera. Partial nucleotide sequencing and inferred amino acid sequence showed greater than 90% homology with the group II allergen from Lolium perenne (Lol II) indicating they encode the group II equivalent, Dac g II. Western blot immunoprobing of recombinant lysates with rabbit polyclonal, mouse monoclonal and human polyclonal antisera demonstrates immunological identity between recombinant Dac g II, Lol p I and Lol p II. Similar cross-identity is observed with pollen extracts from three other grass species: Festuca rubra, Phleum pratense and Anthoxanthum odoratum. Recombinant Dac g II was recognized by species- and group-cross-reactive human IgE antibodies in 33% (4/12) of sera randomly selected from grass-sensitive individuals and in 67% (14/21) of sera from patients receiving grass pollen immunotherapy, whilst 0/4 sera from patients receiving venom immunotherapy alone contained Dac g II cross-reactive IgE. Cross-reactive IgG4 antibodies were detectable in 95% of sera from grass pollen immunotherapy patients. These preliminary data suggest that conventional grass pollen allergoid desensitization immunotherapy may induce IgE responses to a cross-reactive epitope(s) co-expressed by grass pollen groups I and II (and possibly group III) allergens.
authors.affiliation: University Department of Clinical Biochemistry, Queen Elizabeth Medical Center, Birmingham, U.K.
authors.forename: A M
authors.initials: AM
authors.lastname: Roberts
authors.forename: R
authors.initials: R
authors.lastname: Van Ree
authors.forename: S M
authors.initials: SM
authors.lastname: Cardy
authors.forename: L J
authors.initials: LJ
authors.lastname: Bevan
authors.forename: M R
authors.initials: MR
authors.lastname: Walker
mesh_terms: D000485:Allergens / Q000235:genetics / Q000276:immunology*; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D001483:Base Sequence; D015153:Blotting, Western; D002846:Chromatography, Affinity; D003429:Cross Reactions; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology* / Q000628:therapy; D007073:Immunoglobulin E / Q000096:biosynthesis / Q000276:immunology*; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000276:immunology; D007167:Immunotherapy; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D010940:Plant Proteins; D006109:Poaceae / Q000276:immunology; D011058:Pollen / Q000276:immunology*; D011852:Radioallergosorbent Test; D011993:Recombinant Fusion Proteins / Q000276:immunology; D012689:Sequence Homology, Nucleic Acid
chemical_list: D000485:Allergens; D052179:Antigens, Plant; C076702:Dac g II allergen, Dactylis glomerata; D007074:Immunoglobulin G; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D007073:Immunoglobulin E