A Cohort Study of Operationally Tolerant Allograft Recipients

This is a multi-center, prospective, observational study in which operationally tolerant recipients of liver or kidney allografts will be followed longitudinally, with annual collections of clinical data and biological samples. All participants will be followed for the duration of the study, regardless of changes in their tolerance status. Participants will be recruited by three main pathways: 1. Tolerant participants from current and past Immune Tolerance Network (ITN) trials, including those who have already completed trial participation and those who are anticipated to complete trial participation, 2. Tolerant participants referred by ITN affiliated investigators, academic and community transplant physicians and directly through outreach to transplant affinity groups such as the National Kidney Foundation (NKF), and 3. Tolerant participants from the general transplant community who are reachable through general contact channels such as the ITN website, word-of-mouth referrals from existing participants, and social media.