title: IgA-producing plasma cells originate from germinal centers that are induced by B-cell receptor engagement in humans.
abstract: OBJECTIVE
  IgA contributes to homeostatic balance between host and intestinal microbiota. Mechanisms that initiate the IgA response are unclear and likely to differ between humans and animal models. We used multiple experimental approaches to investigate the origin of human intestinal plasma cells that produce IgA in the gastrointestinal tract.
  
  
  METHODS
  Complexity of IgA-producing plasma cell populations in human gastrointestinal mucosa and bone marrow and the specific response to oral cholera vaccine were compared by analysis of immunoglobulin genes. Flow cytometry, gene expression analysis, and immunohistochemistry were used to analyze signaling pathways induced by B-cell receptor engagement in human gut-associated lymphoid tissue (GALT) and involvement of innate immunity in B-cell activation in GALT compared with nonintestinal sites.
  
  
  RESULTS
  Human intestinal IgA-producing plasma cells appeared to be of germinal center origin; there was no evidence for the population complexity that accompanies multiple pathways of derivation observed in bone marrow. In germinal center B cells of human GALT, Btk and Erk are phosphorylated, CD22 is down-regulated, Lyn is translocated to the cell membrane, and Fos and Jun are up-regulated; these features indicate B-cell receptor ligation during germinal center evolution. No differences in innate activation of B cells were observed in GALT, compared with peripheral immune compartments.
  
  
  CONCLUSIONS
  IgA-producing plasma cells appear to be derived from GALT germinal centers in humans. B-cell receptor engagement promotes formation of germinal centers of GALT, with no more evidence for innate immune receptor activation in the mucosa than nonintestinal immune compartments. Germinal centers in GALT should be targets of mucosal vaccinations because they are the source of human intestinal IgA response.
authors.affiliation: Peter Gorer Department of Immunobiology, King's College London, Guy's Hospital, London, UK.
authors.forename: Francesca
authors.initials: F
authors.lastname: Barone
authors.forename: Anna
authors.initials: A
authors.lastname: Vossenkamper
authors.forename: Laurent
authors.initials: L
authors.lastname: Boursier
authors.forename: Wen
authors.initials: W
authors.lastname: Su
authors.forename: Alan
authors.initials: A
authors.lastname: Watson
authors.forename: Susan
authors.initials: S
authors.lastname: John
authors.forename: Deborah K
authors.initials: DK
authors.lastname: Dunn-Walters
authors.forename: Paul
authors.initials: P
authors.lastname: Fields
authors.forename: Sonali
authors.initials: S
authors.lastname: Wijetilleka
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Edgeworth
authors.forename: Jo
authors.initials: J
authors.lastname: Spencer
mesh_terms: D000284:Administration, Oral; D000077329:Agammaglobulinaemia Tyrosine Kinase; D000368:Aged; D001402:B-Lymphocytes / Q000276:immunology*; D022121:Cholera Vaccines / Q000008:administration & dosage / Q000276:immunology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D005803:Genes, Immunoglobulin; D018858:Germinal Center / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007113:Immunity, Innate / Q000235:genetics; D018928:Immunity, Mucosal / Q000235:genetics; D007070:Immunoglobulin A / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation; D008875:Middle Aged; D010766:Phosphorylation; D010950:Plasma Cells / Q000276:immunology* / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D011947:Receptors, Antigen, B-Cell / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051918:Sialic Acid Binding Ig-like Lectin 2 / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: C497867:CD22 protein, human; D022121:Cholera Vaccines; D007070:Immunoglobulin A; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011947:Receptors, Antigen, B-Cell; D051918:Sialic Acid Binding Ig-like Lectin 2; D011505:Protein-Tyrosine Kinases; D000077329:Agammaglobulinaemia Tyrosine Kinase; C000625949:BTK protein, human; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D048049:Extracellular Signal-Regulated MAP Kinases