title: Biomarkers of tolerance.
abstract: OBJECTIVE
  As the induction and maintenance of donor-specific tolerance is a central aim in solid organ transplantation, it is essential that clinicians are able to identify and monitor tolerance accurately and reliably. This review highlights recent advances in defining sets of biomarkers in noninvasive samples that may guide minimization and withdrawal of immunosuppression in tolerant recipients.
  
  
  RESULTS
  Recent studies in liver and kidney transplant recipients have identified distinct biomarker profiles that are associated with operational tolerance. Although there is some heterogeneity in the findings of these studies, these have suggested novel cellular mechanisms for the development of tolerance.
  
  
  CONCLUSIONS
  Multiple platforms such as microarray gene expression analysis, flow cytometry, and immune cell functional assays have been used to discover and validate composite sets of biomarkers, which identify recipients with operational tolerance both in liver and kidney transplantation. These studies suggest that distinct cellular and molecular mechanisms lead to the development of tolerance in different transplanted organs. These putative biomarker profiles now need to be validated prospectively in trials of immunosuppression withdrawal and in novel approaches to induce transplant tolerance.
authors.affiliation: King's College London, MRC Centre for Transplantation, London, UK.
authors.forename: Refik
authors.initials: R
authors.lastname: Gökmen
authors.forename: Maria P
authors.initials: MP
authors.lastname: Hernandez-Fuentes
mesh_terms: D015415:Biomarkers / Q000378:metabolism*; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D006801:Humans; D016030:Kidney Transplantation / Q000276:immunology; D016031:Liver Transplantation / Q000276:immunology*; D012333:RNA, Messenger / Q000032:analysis; D060888:Real-Time Polymerase Chain Reaction; D023001:Transplantation Tolerance / Q000276:immunology*
chemical_list: D015415:Biomarkers; D012333:RNA, Messenger