title: Circulating FVIII-specific IgG, IgA and IgM memory B cells from haemophilia A patients.
abstract: BACKGROUND
  Approximately, 25% of haemophilia A (HA) patients treated by factor VIII (FVIII), develop antibodies, known as inhibitors, neutralizing the activity of infused FVIII. This immune response involves B cells (BC), including FVIII-specific memory B cells (MBC). Production of anti-FVIII antibodies after stimulation of FVIII-specific MBC suggests a role of these cells in the immune response to FVIII. Animal models allowed the study of circulating FVIII-specific cells, however few data are available on HA patients.
  
  
  OBJECTIVE
  In the present study, we simultaneously detected, via ELISpot assay, different isotypes of MBC in the blood of HA patients, after polyclonal activation. Patients included: three with active inhibitors; three with a history of inhibitors; six without any past or active inhibitor.
  
  
  RESULTS
  FVIII-specific MBC were detected in peripheral blood of HA patients: (i) patients with active inhibitors (IgG: 4-5.2/10(6) BC; IgA: 2.9-4/10(6) BC) (ii) patients with a past of inhibitors (no IgG BC; IgA: 5-7.5/10(6) BC) (iii) patients without inhibitors (no IgG BC or IgA BC except one patient had two FVIII-specific IgA BC/10(6) BC).
  
  
  CONCLUSIONS
  FVIII-specific IgA MBC were detected in HA patients with past and current immune responses against FVIII and FVIII-specific IgG MBC were found only in those with positive inhibitors. This study shows the possibility to detect and characterize easily and simultaneously the MBC from patient blood and that MBC seem different according to anti-FVIII immune history. It could be a useful tool to study anti-FVIII response and Immune Tolerance Induction cellular mechanisms.
authors.affiliation: Laboratory of Hematology, University Hospital of Montpellier, Montpellier, France. diazisa@hotmail.fr.|Institute of Research in Biotherapy, Montpellier, France. diazisa@hotmail.fr.
authors.forename: I
authors.initials: I
authors.lastname: Diaz
authors.affiliation: Institute of Research in Biotherapy, Montpellier, France.|INSERM U1058, Montpellier 1 University, Montpellier, France.
authors.forename: K
authors.initials: K
authors.lastname: Bolloré
authors.affiliation: Institute of Research in Biotherapy, Montpellier, France.|INSERM U1058, Montpellier 1 University, Montpellier, France.
authors.forename: E
authors.initials: E
authors.lastname: Tuaillon
authors.affiliation: UMR 3145 SysDiag CNRS/Biorad, Montpellier, France.
authors.forename: P
authors.initials: P
authors.lastname: Lapalud
authors.affiliation: Regional Hemophilia Treatment Center, Montpellier, France.
authors.forename: M
authors.initials: M
authors.lastname: Giansily-Blaizot
authors.affiliation: INSERM U1058, Montpellier 1 University, Montpellier, France.
authors.forename: J P
authors.initials: JP
authors.lastname: Vendrell
authors.affiliation: Laboratory of Hematology, University Hospital of Montpellier, Montpellier, France.|Regional Hemophilia Treatment Center, Montpellier, France.
authors.forename: J F
authors.initials: JF
authors.lastname: Schved
authors.affiliation: UMR 3145 SysDiag CNRS/Biorad, Montpellier, France.|Regional Hemophilia Treatment Center, Montpellier, France.
authors.forename: G
authors.initials: G
authors.lastname: Lavigne-Lissalde
mesh_terms: D000293:Adolescent; D000328:Adult; D057134:Antibodies, Neutralizing / Q000097:blood; D001402:B-Lymphocytes / Q000166:cytology / Q000378:metabolism*; D016022:Case-Control Studies; D002648:Child; D058501:Enzyme-Linked Immunospot Assay; D005169:Factor VIII / Q000276:immunology*; D005434:Flow Cytometry; D006467:Hemophilia A / Q000473:pathology; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood* / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology; D007075:Immunoglobulin M / Q000097:blood* / Q000276:immunology; D055815:Young Adult
chemical_list: D057134:Antibodies, Neutralizing; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D005169:Factor VIII
keywords: ELISpot; factor VIII; haemophilia A; inhibitors; memory B cells