Graft Rejection

This study will provide follow-up evaluation and care of patients who have undergone allogeneic (donor) stem cell transplantation at the NIH Clinical Center. Patients are monitored for their response to treatment, disease relapse, and later-occurring effects of the transplant. Patients between 10 and 80 years of age who received a donor stem cell transplant at the NIH Clinical Center under an NHLBI protocol may be eligible for this study. Candidates must have had their first transplant at least 3 years before entering the current study. Participants are generally seen in the clinic every 12 months for some or all of the following procedures: * Periodic physical examinations, eye examinations, and blood and urine tests. * Bone marrow aspiration and biopsy: A sample of bone marrow is obtained for microscopic examination. The patient is given local anesthesia or conscious sedation. An area of the hipbone is numbed, a thin needle is inserted through the skin into the bone, and a small amount of marrow is withdrawn. * Tissue biopsy: A small piece of tissue or tumor is obtained for microscopic examination. Depending on the site of the biopsy, the tissue may be removed using a cookie cutter-like "punch" instrument, a needle, or a knife. The area is numbed and the tissue is removed with the appropriate tool. * Imaging tests to visualize organs, tissues, and cellular activity in specific tissues. For these tests, the patient lies on a table that slides into the scanner. They may include the following: 1. Nuclear scans use a sensitive camera to track a small amount of radioactive material (radioisotope) that is given to the patient by mouth or through a vein. The scan may show abnormal areas of tissue in the bones, liver, spleen, kidney, brain, thyroid, or spine. 2. Magnetic resonance imaging (MRI) uses a magnetic field and radio waves to examine small sections of body organs and tissues. 3. Computerized tomography (CT) uses x-rays and can be done from different angles to provide a 3-dimensional view of tissues and organs. 4. Positron emission tomography (PET) uses a fluid with a radioisotope attached to it to show cellular activity in specific tissues. The fluid is given through a vein and travels to the cells that are most active (like cancer cells), showing if there is an actively growing tumor. * Pulmonary (lung) function tests: The patient breathes into a machine that measures the volume of air the person can move into and out of the lungs. * Heart function tests may include the following: 1. Electrocardiogram (EKG) evaluates the electrical activity of the heart. Electrodes placed on the chest transmit information from the heart to a machine. 2. Echocardiogram (Echo) is an ultrasound test that uses sound waves to create an image of the heart and examine the function of the heart chambers and valves. 3. Multiple gated acquisition scan (MUGA) is a nuclear medicine test that uses a small amount of radioactive chemical injected into a vein. A special scanner creates an image of the heart for examining the beating motion of the muscle. Disease relapse or progression, or transplant-related problems may be treated with standard medical, radiation, or surgical therapy, or patients may be offered experimental therapy.

This study aims to develop and refine a microRNA (miR) biomarker panel that can be used to phenotype net immune state after heart transplantation using circulating miRs (associated with drug doses and levels). These miRs will be used to characterize the overall immune state in adult heart transplant patients and predict patients that will go on to develop infection and rejection. MicroRNAs (miRs) are small, non-coding RNA molecules that regulate gene expression and serve as molecular biomarkers found in the circulation.

This study aims to discover circulating microRNAs (associated with drug doses and levels) that can be used to characterize the overall immune state in pediatric heart transplant patients and predict patients that will go on to develop infection and rejection. MicroRNAs (miRs) are small, non-coding RNA molecules that regulate gene expression and serve as molecular biomarkers found in the circulation.

The goal of this observational study is to evaluate whether molecular analysis of donor heart biopsies taken at the time of organ removal ("Time Zero") can help predict the future function and rejection risk of the transplanted heart in adult transplant recipients. The main questions it aims to answer are: * Can early molecular injury in the donor heart, caused by brain death or circulatory death, be detected at the time of organ removal? * Can these early molecular findings predict short-, mid-, and long-term transplant outcomes, such as graft function or rejection? Participants will: * Include heart donors whose hearts are being transplanted (both standard and marginal donors, including DBD and DCD cases) * Provide two small biopsies from the donor heart at the time of organ removal: one for routine pathology, one for microarray-based molecular analysis * Have routine follow-up biopsies after transplantation as part of standard care (no additional procedures required beyond medical standard) Researchers will compare biopsy results from different donor types (standard vs. marginal, DBD vs. DCD) to see if early molecular signals are linked to later heart transplant outcomes.

The objective of this study is to describe the type of cell death induced by extracorporeal photochemotherapy, depending on the cell type, using a panel of complementary analysis techniques.

The goal of this clinical trial is to compare the degree of HLA sensitization at 2 years in patients with late renal graft failure (\> 3 months) when receiving reduced immunosuppressant treatment versus stopping immunosuppression at 6 months. The main question this study aims to answer is: Does maintaining long-term immunosuppression in patients with a late renal graft failure (\> 3 months) safely reduce the risk of HLA sensitization? To answer this question, patients will be assigned to a control arm or investigational arm: * Patients assigned to the control arm will receive standard treatment, in which immunosuppressant treatment is withdrawn after 6 months. * Patients assigned to the investigatonal arm will continue immunosuppressant treatment at low doses for 2 years. Patients recruited in this clinical trial will be followed for up to 2 years. During this time, patients will visit the clinic every 3 months for checkups and tests.

BK virus (BKV) is a ubiquitous virus that infects more than 80% of the population. In case of immunosuppression, BKV can replicate and induce nephropathies in renal transplant recipients or haemorrhagic cystitis in bone marrow transplant recipients. The disruption of the balance between BKV replication and immune control is considered the key element in the development of these pathologies. During lung transplantation, patients undergo intense immunosuppression that favors the reactivation of persistent viruses such as EBV, CMV and probably BKV. Although the data on EBV and CMV reactivation are very clear and allow optimal management, the prevalence of BKV replication and its clinical impact in lung transplant recipients remains unknown at this time. The aim of this study is to know the incidence and clinical impact of BKV replication in lung transplant recipients. Moreover, the results will help to better understand the interaction between the virus and his host, with a focus on the humoral and cellular immune response against BKV. The results could possibly enable to define predictive markers of BKV replication and of its evolution.