title: Isolation, cloning and allergenic reactivity of natural profilin Cit s 2, a major orange allergen.
abstract: BACKGROUND
  Orange is among the most widely consumed fruits, and among the plant food sources causing allergic reactions according to popular perception. However, its relevant allergenic components are virtually unknown. Profilin is a well-defined minor plant panallergen, showing prevalences around 30% in fruits and vegetables.
  
  
  METHODS
  Twenty-three orange-allergic patients were studied. Natural orange profilin, named Cit s 2, was purified by affinity chromatography and characterized by N-terminal amino acid sequencing, matrix-assisted laser desorption/ionization mass spectrometry analysis and isolation of its coding cDNA. Reactivity to Cit s 2 was analyzed in vivo by skin prick tests (SPT) and in vitro by IgE immunodetection, specific IgE determination in individual sera and enzyme-linked immunosorbent assay-inhibition assays.
  
  
  RESULTS
  The N-terminal amino acid sequence and molecular mass of natural Cit s 2, both fully in agreement with the complete amino acid sequence deduced from its coding cDNA, demonstrated its profilin nature. An unexpectedly high reactivity to Cit s 2 was found in vivo (78% of positive SPT responses) and in vitro (87% of sera from orange allergic patients had specific IgE to Cit s 2). The purified allergen inhibited around 50% of the IgE binding to an orange pulp extract.
  
  
  CONCLUSIONS
  Orange profilin Cit s 2, unlike other plant food profilins, is a major and highly prevalent allergen.
authors.affiliation: Unidad de Bioquímica, Departamento de Biotecnología, E.T.S. Ingenieros Agrónomos, Madrid, Spain.
authors.forename: G
authors.initials: G
authors.lastname: López-Torrejón
authors.forename: M D
authors.initials: MD
authors.lastname: Ibáñez
authors.forename: O
authors.initials: O
authors.lastname: Ahrazem
authors.forename: R
authors.initials: R
authors.lastname: Sánchez-Monge
authors.forename: J
authors.initials: J
authors.lastname: Sastre
authors.forename: M
authors.initials: M
authors.lastname: Lombardero
authors.forename: D
authors.initials: D
authors.lastname: Barber
authors.forename: G
authors.initials: G
authors.lastname: Salcedo
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D000595:Amino Acid Sequence; D000918:Antibody Specificity; D052179:Antigens, Plant; D002648:Child; D002846:Chromatography, Affinity; D032084:Citrus sinensis / Q000009:adverse effects* / Q000737:chemistry / Q000276:immunology; D005260:Female; D005512:Food Hypersensitivity / Q000097:blood / Q000175:diagnosis / Q000209:etiology*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D007223:Infant; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010940:Plant Proteins / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D051304:Profilins / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D016415:Sequence Alignment; D012882:Skin Tests
chemical_list: D000485:Allergens; D052179:Antigens, Plant; C508891:Cit s 2 allergen, orange; D010940:Plant Proteins; D051304:Profilins; D007073:Immunoglobulin E