title: Rethinking the multiple roles of B cells in organ transplantation.
abstract: OBJECTIVE
  To discuss the B-cell diverse functions in organ transplantation, highlighting the emerging debate on the role of regulatory B cells (Bregs). We underscore the need to re-examine and integrate data on B-cell functional activities, aiming to discriminate their regulatory (REG) and inflammatory (INFLAMMA) functions and to translate this knowledge for the development of novel immunomodulatory therapeutic strategies and to rethink the current ones.
  
  
  RESULTS
  Data from both experimental models and clinical trials point that B cells of various phenotypes have immunoregulatory activity and play an important role in controlling graft inflammation. Data on the state of operational tolerance, in kidney transplantation, suggest the relevance of preserving a healthy B-cell compartment - in numbers and in the Breg capacity to activate the CD40/STAT3 signalling pathway - for achieving and maintaining homeostasis. Moreover, autoantibodies also comprise transplant immunobiology and it seems that not all alloantibodies are deleterious.
  
  
  CONCLUSIONS
  The role of B cells, in organ transplantation, can no longer be taken as mere generators of plasma cells, which produce alloantibodies deleterious to the graft. B cells also seem to integrate a complex immunoregulatory network in organ transplantation, with Bregs of various phenotypes and possibly also antibodies. The functional discrimination of REG/INFLAMMA B-cell roles needs to be considered in the clinical setting.
authors.affiliation: Laboratory of Immunology, Heart Institute, University of São Paulo Medical School, São Paulo, Brazil. vecoelho@usp.br
authors.forename: Verônica
authors.initials: V
authors.lastname: Coelho
authors.forename: David
authors.initials: D
authors.lastname: Saitovitch
authors.forename: Jorge
authors.initials: J
authors.lastname: Kalil
authors.forename: Hernandez Moura
authors.initials: HM
authors.lastname: Silva
mesh_terms: D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000276:immunology / Q000627:therapeutic use; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D060151:B-Lymphocytes, Regulatory / Q000166:cytology / Q000276:immunology; D002465:Cell Movement / Q000276:immunology; D006084:Graft Rejection / Q000276:immunology* / Q000517:prevention & control; D006801:Humans; D007111:Immunity, Cellular / Q000276:immunology*; D007249:Inflammation / Q000276:immunology; D007518:Isoantibodies / Q000276:immunology; D016030:Kidney Transplantation / Q000276:immunology; D010641:Phenotype; D014181:Transplantation Immunology / Q000276:immunology*; D023001:Transplantation Tolerance / Q000276:immunology*
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D007518:Isoantibodies