title: Monitoring pharmacologically induced immunosuppression by immune repertoire sequencing to detect acute allograft rejection in heart transplant patients: a proof-of-concept diagnostic accuracy study.
abstract: BACKGROUND
  It remains difficult to predict and to measure the efficacy of pharmacological immunosuppression. We hypothesized that measuring the B-cell repertoire would enable assessment of the overall level of immunosuppression after heart transplantation.
  
  
  RESULTS
  In this proof-of-concept study, we implemented a molecular-barcode-based immune repertoire sequencing assay that sensitively and accurately measures the isotype and clonal composition of the circulating B cell repertoire. We used this assay to measure the temporal response of the B cell repertoire to immunosuppression after heart transplantation. We selected a subset of 12 participants from a larger prospective cohort study (ClinicalTrials.gov NCT01985412) that is ongoing at Stanford Medical Center and for which enrollment started in March 2010. This subset of 12 participants was selected to represent post-heart-transplant events, with and without acute rejection (six participants with moderate-to-severe rejection and six without). We analyzed 130 samples from these patients, with an average follow-up period of 15 mo. Immune repertoire sequencing enables the measurement of a patient's net state of immunosuppression (correlation with tacrolimus level, r = -0.867, 95% CI -0.968 to -0.523, p = 0.0014), as well as the diagnosis of acute allograft rejection, which is preceded by increased immune activity with a sensitivity of 71.4% (95% CI 30.3% to 94.9%) and a specificity of 82.0% (95% CI 72.1% to 89.1%) (cell-free donor-derived DNA as noninvasive gold standard). To illustrate the potential of immune repertoire sequencing to monitor atypical post-transplant trajectories, we analyzed two more patients, one with chronic infections and one with amyloidosis. A larger, prospective study will be needed to validate the power of immune repertoire sequencing to predict rejection events, as this proof-of-concept study is limited to a small number of patients who were selected based on several criteria including the availability of a large number of samples and the absence or presence of rejection events.
  
  
  CONCLUSIONS
  If confirmed in larger, prospective studies, the method described here has potential applications in the tailored management of post-transplant immunosuppression and, more broadly, as a method for assessing the overall activity of the immune system.
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, California, United States of America; Department of Applied Physics, Stanford University, Stanford, California, United States of America.
authors.forename: Christopher
authors.initials: C
authors.lastname: Vollmers
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, California, United States of America; Department of Applied Physics, Stanford University, Stanford, California, United States of America; Howard Hughes Medical Institute, Stanford, California, United States of America.
authors.forename: Iwijn
authors.initials: I
authors.lastname: De Vlaminck
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Hannah A
authors.initials: HA
authors.lastname: Valantine
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, California, United States of America; Department of Applied Physics, Stanford University, Stanford, California, United States of America.
authors.forename: Lolita
authors.initials: L
authors.lastname: Penland
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Helen
authors.initials: H
authors.lastname: Luikart
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Calvin
authors.initials: C
authors.lastname: Strehl
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Garrett
authors.initials: G
authors.lastname: Cohen
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Kiran K
authors.initials: KK
authors.lastname: Khush
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, California, United States of America; Department of Applied Physics, Stanford University, Stanford, California, United States of America; Howard Hughes Medical Institute, Stanford, California, United States of America.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Quake
mesh_terms: D064591:Allografts; D001402:B-Lymphocytes / Q000276:immunology*; D005260:Female; D006084:Graft Rejection / Q000175:diagnosis* / Q000276:immunology*; D016027:Heart Transplantation; D006801:Humans; D007165:Immunosuppression Therapy / Q000379:methods*; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008297:Male; D015166:Monitoring, Immunologic / Q000379:methods*; D011446:Prospective Studies; D012680:Sensitivity and Specificity
chemical_list: D007166:Immunosuppressive Agents