title: Phenotype and functions of B cells in patients with acute brain injuries.
abstract: BACKGROUND
  Brain injuries (BI) induce a state of systemic immunosuppression, leading to a high risk of pneumonia. In this pilot study, we investigated the status of B cell compartment in BI patients.
  
  
  METHODS
  A prospective observational study was performed in 2 intensive care units in a university hospital. Blood samples were collected in 14 patients at day 1 and day 7 after acute BI. The phenotype and the ability of B cells to secrete IL-10 were compared to 11 healthy volunteers (HV).
  
  
  RESULTS
  Among the circulating lymphocytes, the frequency of B cells was significantly higher in BI patients compared to HV (p<0.001). B cells from BI patients displayed an activated profil on day 7 after BI, reflected by a significantly higher proportion of CD27(+) memory (p=0.01) and CD27(+) IgD(-) switched memory B cells (p=0.02), as well as a significantly higher blood level of IgA (p=0.001) and IgM (p<0.001) as compared to day 1. The frequency of IL-10 secreting B cells (IL-10(+) B cells) on day 1 and day 7 was significantly lower in BI patients compared to HV (p<0.05). Interestingly, we observed that all BI patients with high frequency of IL-10(+) B cells on day 1 displayed an episode of pneumonia, and had a longer duration of mechanical ventilation and ICU stay compared to BI patients with low proportion of IL-10(+) B cells.
  
  
  CONCLUSIONS
  This study provides an extensive description of the phenotype and function of B cells in BI patients. Our results suggest that IL-10(+) B cells could play a major role in immunosuppression after BI.
authors.affiliation: INSERM, UMR 1064, Nantes F-44093, France; CHU de Nantes, ITUN, Nantes F-44093, France.
authors.forename: Alexis
authors.initials: A
authors.lastname: Chenouard
authors.affiliation: INSERM, UMR 1064, Nantes F-44093, France; CHU de Nantes, ITUN, Nantes F-44093, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Chesneau
authors.affiliation: INSERM, UMR 1064, Nantes F-44093, France; CHU de Nantes, ITUN, Nantes F-44093, France.
authors.forename: Faouzi
authors.initials: F
authors.lastname: Braza
authors.affiliation: Biochemistry Laboratory, Nantes University Hospital, Nantes, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dejoie
authors.affiliation: Intensive Care Unit, Anesthesia and Critical Care Department, Nantes University Hospital, Nantes, France.
authors.forename: Raphael
authors.initials: R
authors.lastname: Cinotti
authors.affiliation: Intensive Care Unit, Anesthesia and Critical Care Department, Nantes University Hospital, Nantes, France; Thérapeutiques Cliniques et Expérimentales des Infections, EA 3826 Nantes, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Roquilly
authors.affiliation: INSERM, UMR 1064, Nantes F-44093, France; CHU de Nantes, ITUN, Nantes F-44093, France; CIC biothérapie, Nantes F-44035, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Brouard
authors.affiliation: Intensive Care Unit, Anesthesia and Critical Care Department, Nantes University Hospital, Nantes, France; Thérapeutiques Cliniques et Expérimentales des Infections, EA 3826 Nantes, France. Electronic address: karim.asehnoune@chu-nantes.fr.
authors.forename: Karim
authors.initials: K
authors.lastname: Asehnoune
mesh_terms: D000328:Adult; D000368:Aged; D001402:B-Lymphocytes / Q000276:immunology* / Q000473:pathology; D001930:Brain Injuries / Q000150:complications / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D005260:Female; D015870:Gene Expression; D006801:Humans; D016867:Immunocompromised Host; D007070:Immunoglobulin A / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D007156:Immunologic Memory; D016130:Immunophenotyping; D007362:Intensive Care Units; D016753:Interleukin-10 / Q000235:genetics / Q000276:immunology*; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D018410:Pneumonia, Bacterial / Q000150:complications / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D011446:Prospective Studies; D012121:Respiration, Artificial; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000235:genetics / Q000276:immunology
chemical_list: C508609:IL10 protein, human; D007070:Immunoglobulin A; D007075:Immunoglobulin M; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; D016753:Interleukin-10
keywords: B cells; Brain injury; IL-10; IL-10(+) B cells; Immune suppression; Regulatory B cells