title: Lol p XI, a new major grass pollen allergen, is a member of a family of soybean trypsin inhibitor-related proteins.
abstract: BACKGROUND
  Monoclonal antibodies were obtained against an unknown allergen from Lolium perenne grass pollen. The allergen had an apparent molecular mass of 18 kd on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Earlier immunoblotting studies had shown that carbohydrate-specific IgG antibodies recognize an antigen of similar size.
  
  
  OBJECTIVE
  We sought to characterize the allergen biochemically and immunologically.
  
  
  METHODS
  The amino acid sequence of the allergen was determined by automated Edman degradation, and its monosaccharide composition was determined by gas chromatographic analysis. A panel of 270 grass pollen-positive sera was assessed in a RAST with the purified allergen. Protease digestion (proteinase K) and chemical deglycosylation (trifluoromethane sulfonic acid) were used to distinguish between carbohydrate and peptide epitopes for IgE antibodies.
  
  
  RESULTS
  The allergen was shown to be a glycoprotein with a molecular mass of 16 kd, of which 8% is carbohydrate. Its amino acid sequence shares 32% homology with soybean trypsin inhibitor (Kunitz) but lacks its active site. No homology was found with known grass pollen allergens, hence it was designated Lol p XI. A high degree of homology (44%) was found with a tree pollen allergen, Ole e I, the major allergen of olive pollen. More than 65% of grass pollen-positive sera had IgE against Lol p XI. IgE reactivity was demonstrated both with the carbohydrate moiety and the peptide backbone.
  
  
  CONCLUSIONS
  Lol p XI is a new major grass pollen allergen carrying an IgE-binding carbohydrate determinant. Lol p XI is structurally related to the major allergen from olive pollen.
authors.affiliation: Central Laboratory of The Netherlands Red Cross Blood Transfusion Service, Amsterdam.
authors.forename: R
authors.initials: R
authors.lastname: van Ree
authors.forename: D R
authors.initials: DR
authors.lastname: Hoffman
authors.forename: W
authors.initials: W
authors.lastname: van Dijk
authors.forename: V
authors.initials: V
authors.lastname: Brodard
authors.forename: K
authors.initials: K
authors.lastname: Mahieu
authors.forename: C A
authors.initials: CA
authors.lastname: Koeleman
authors.forename: M
authors.initials: M
authors.lastname: Grande
authors.forename: W A
authors.initials: WA
authors.lastname: van Leeuwen
authors.forename: R C
authors.initials: RC
authors.lastname: Aalberse
mesh_terms: D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D001665:Binding Sites; D006023:Glycoproteins / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D008129:Lolium / Q000737:chemistry / Q000276:immunology*; D008969:Molecular Sequence Data; D009005:Monosaccharides / Q000032:analysis / Q000276:immunology; D010940:Plant Proteins / Q000737:chemistry / Q000276:immunology*; D011058:Pollen / Q000737:chemistry / Q000276:immunology*; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D014360:Trypsin Inhibitor, Kunitz Soybean / Q000737:chemistry / Q000276:immunology
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D006023:Glycoproteins; C093636:Lol p XI protein, Lolium perenne; D009005:Monosaccharides; D010940:Plant Proteins; D007073:Immunoglobulin E; D014360:Trypsin Inhibitor, Kunitz Soybean