title: Epitope analysis of Ara h 2 and Ara h 6: characteristic patterns of IgE-binding fingerprints among individuals with similar clinical histories.
abstract: BACKGROUND
  Ara h 2 and Ara h 6 are moderately homologous and highly potent peanut allergens.
  
  
  OBJECTIVE
  To identify IgE-binding linear epitopes of Ara h 6, compare them to those of Ara h 2, and to stratify binding based on clinical histories.
  
  
  METHODS
  Thirty highly peanut-allergic subjects were stratified by clinical history. Sera were diluted to contain the same amount of anti-peanut IgE. IgE binding to overlapping 20-mer peptides of Ara h 2 and Ara h 6 was assessed using microarrays.
  
  
  RESULTS
  Each subject had a unique IgE-binding fingerprint to peptides; these data were coalesced into epitope binding. IgE from subjects with a history of more severe reactions (n = 19) had a smaller frequency of binding events (BEs) for both Ara h 2 (52 BEs of 152 (19X8epitopes) possible BEs and Ara h 6 (13 BEs of 133 (19X7 epitopes) possible BEs) compared to IgE from those with milder histories (n = 11) (Ara h 2: 47 BEs of 88 (11X8 epitopes) possible BEs, P < 0.01; Ara h 6: 25 BEs of 77 (11X7 epitopes) possible BEs, P < 0.001). Using an unsupervised hierarchal cluster analysis, subjects with similar histories tended to cluster. We have tentatively identified a high-risk pattern of binding to peptides of Ara h 2 and Ara h 6, predominantly in subjects with a history of more severe reactions (OR = 12.6; 95% CI: 2.0-79.5; P < 0.01).
  
  
  CONCLUSIONS
  IgE from patients with more severe clinical histories recognize fewer linear epitopes of Ara h 2 and Ara h 6 than do subjects with milder reactions and bind these epitopes in characteristic patterns. Close examination of IgE binding to epitopes of Ara h 2 and Ara h 6 may have prognostic value.
authors.affiliation: Division of Allergy and Clinical Immunology and Departments of Medicine and Immunology, University of Colorado Denver, Aurora, CO, USA.
authors.forename: K
authors.initials: K
authors.lastname: Otsu
authors.forename: R
authors.initials: R
authors.lastname: Guo
authors.forename: S C
authors.initials: SC
authors.lastname: Dreskin
mesh_terms: D055516:2S Albumins, Plant / Q000737:chemistry / Q000276:immunology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D000818:Animals; D052179:Antigens, Plant / Q000737:chemistry / Q000276:immunology*; D002460:Cell Line; D002648:Child; D016000:Cluster Analysis; D018604:Epitope Mapping; D000939:Epitopes / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D006023:Glycoproteins / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology / Q000378:metabolism; D008875:Middle Aged; D008958:Models, Molecular; D008969:Molecular Sequence Data; D021183:Peanut Hypersensitivity / Q000276:immunology*; D010455:Peptides / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D040081:Protein Array Analysis; D011485:Protein Binding / Q000276:immunology; D011487:Protein Conformation; D051381:Rats; D055815:Young Adult
chemical_list: D055516:2S Albumins, Plant; D052179:Antigens, Plant; C500890:Ara h 2 allergen, Arachis hypogaea; C492737:Ara h 6 allergen, Arachis hypogaea; D000939:Epitopes; D006023:Glycoproteins; D010455:Peptides; D007073:Immunoglobulin E
keywords: Ara h 2; Ara h 6; IgE; allergens; microarrays; peanut; peptides