title: Peanut oral immunotherapy transiently expands circulating Ara h 2-specific B cells with a homologous repertoire in unrelated subjects.
abstract: BACKGROUND
  Peanut oral immunotherapy (PNOIT) induces persistent tolerance to peanut in a subset of patients and induces specific antibodies that might play a role in clinical protection. However, the contribution of induced antibody clones to clinical tolerance in PNOIT is unknown.
  
  
  OBJECTIVE
  We hypothesized that PNOIT induces a clonal, allergen-specific B-cell response that could serve as a surrogate for clinical outcomes.
  
  
  METHODS
  We used a fluorescent Ara h 2 multimer for affinity selection of Ara h 2-specific B cells and subsequent single-cell immunoglobulin amplification. The diversity of related clones was evaluated by means of next-generation sequencing of immunoglobulin heavy chains from circulating memory B cells with 2x250 paired-end sequencing on the Illumina MiSeq platform.
  
  
  RESULTS
  Expression of class-switched antibodies from Ara h 2-positive cells confirms enrichment for Ara h 2 specificity. PNOIT induces an early and transient expansion of circulating Ara h 2-specific memory B cells that peaks at week 7. Ara h 2-specific sequences from memory cells have rates of nonsilent mutations consistent with affinity maturation. The repertoire of Ara h 2-specific antibodies is oligoclonal. Next-generation sequencing-based repertoire analysis of circulating memory B cells reveals evidence for convergent selection of related sequences in 3 unrelated subjects, suggesting the presence of similar Ara h 2-specific B-cell clones.
  
  
  CONCLUSIONS
  Using a novel affinity selection approach to identify antigen-specific B cells, we demonstrate that the early PNOIT-induced Ara h 2-specific B-cell receptor repertoire is oligoclonal and somatically hypermutated and shares similar clonal groups among unrelated subjects consistent with convergent selection.
authors.affiliation: Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Mass; Food Allergy Center, Massachusetts General Hospital and MassGeneral Hospital for Children, Boston, Mass; Koch Institute for Integrative Cancer Research at Massachusetts Institute of Technology, Cambridge, Mass. Electronic address: Sarita.patil@mgh.harvard.edu.
authors.forename: Sarita U
authors.initials: SU
authors.lastname: Patil
authors.affiliation: Koch Institute for Integrative Cancer Research at Massachusetts Institute of Technology, Cambridge, Mass.
authors.forename: Adebola O
authors.initials: AO
authors.lastname: Ogunniyi
authors.affiliation: Rho, Chapel Hill, NC.
authors.forename: Agustin
authors.initials: A
authors.lastname: Calatroni
authors.affiliation: Department of Physics, Boston University, Boston, Mass.
authors.forename: Vasisht R
authors.initials: VR
authors.lastname: Tadigotla
authors.affiliation: Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Mass; Food Allergy Center, Massachusetts General Hospital and MassGeneral Hospital for Children, Boston, Mass.
authors.forename: Bert
authors.initials: B
authors.lastname: Ruiter
authors.affiliation: Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Mass.
authors.forename: Alex
authors.initials: A
authors.lastname: Ma
authors.affiliation: Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Mass.
authors.forename: James
authors.initials: J
authors.lastname: Moon
authors.affiliation: Koch Institute for Integrative Cancer Research at Massachusetts Institute of Technology, Cambridge, Mass; Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology, and Harvard Medical School, Boston, Mass.
authors.forename: J Christopher
authors.initials: JC
authors.lastname: Love
authors.affiliation: Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Mass; Food Allergy Center, Massachusetts General Hospital and MassGeneral Hospital for Children, Boston, Mass.
authors.forename: Wayne G
authors.initials: WG
authors.lastname: Shreffler
mesh_terms: D055516:2S Albumins, Plant / Q000276:immunology*; D000284:Administration, Oral; D000293:Adolescent; D000917:Antibody Formation; D052179:Antigens, Plant / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D002648:Child; D002999:Clone Cells; D003888:Desensitization, Immunologic / Q000379:methods*; D000939:Epitopes / Q000276:immunology; D005260:Female; D006023:Glycoproteins / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D007156:Immunologic Memory; D008213:Lymphocyte Activation; D008297:Male; D021183:Peanut Hypersensitivity / Q000276:immunology / Q000628:therapy*
chemical_list: D055516:2S Albumins, Plant; D052179:Antigens, Plant; C500890:Ara h 2 allergen, Arachis hypogaea; D000939:Epitopes; D006023:Glycoproteins; D007073:Immunoglobulin E
keywords: Immunotherapy; antibody repertoire; antigen-specific B cells; food allergy; peanut allergy