Stavros Diamantopoulos

University of Miami, Coral Gables, FL, United States

Are you Stavros Diamantopoulos?

Claim your profile

Publications (3)16.45 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To investigate if recurrent autoimmunity explained hyperglycemia and C-peptide loss in three immunosuppressed simultaneous pancreas-kidney (SPK) transplant recipients. We monitored autoantibodies and autoreactive T-cells (using tetramers) and performed biopsy. The function of autoreactive T-cells was studied with in vitro and in vivo assays. Autoantibodies were present pretransplant and persisted on follow-up in one patient. They appeared years after transplantation but before the development of hyperglycemia in the remaining patients. Pancreas transplant biopsies were taken within approximately 1 year from hyperglycemia recurrence and revealed beta-cell loss and insulitis. We studied autoreactive T-cells from the time of biopsy and repeatedly demonstrated their presence on further follow-up, together with autoantibodies. Treatment with T-cell-directed therapies (thymoglobulin and daclizumab, all patients), alone or with the addition of B-cell-directed therapy (rituximab, two patients), nonspecifically depleted T-cells and was associated with C-peptide secretion for >1 year. Autoreactive T-cells with the same autoantigen specificity and conserved T-cell receptor later reappeared with further C-peptide loss over the next 2 years. Purified autoreactive CD4 T-cells from two patients were cotransplanted with HLA-mismatched human islets into immunodeficient mice. Grafts showed beta-cell loss in mice receiving autoreactive T-cells but not control T-cells. We demonstrate the cardinal features of recurrent autoimmunity in three such patients, including the reappearance of CD4 T-cells capable of mediating beta-cell destruction. Markers of autoimmunity can help diagnose this underappreciated cause of graft loss. Immune monitoring during therapy showed that autoimmunity was not resolved by the immunosuppressive agents used.
    Diabetes 04/2010; 59(4):947-57. · 7.90 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Of deceased pancreas donors, 3-4% may have autoantibodies (AAb) to pancreatic islet cell antigens; these autoantibodies are well-established markers of type 1 diabetes. We investigated whether donor AAb positivity could affect the outcome of pancreas transplantation. We retrospectively tested AAb in 135 donors whose pancreata and kidneys were transplanted in type 1 diabetes patients. We measured AAb to glutamic acid decarboxylase (GAD-AAb), the tyrosine-phosphatase-like protein IA2 (IA2-AAb), and insulin (insulin-AAb). We then evaluated pancreas transplant outcome data. Four of 135 (2.96%) donors were AAb positive: three donors had GAD-AAb, and one donor had insulin-AAb. Their respective recipients became insulin independent on follow-up. Three of the four recipients had normal, insulin-producing grafts 3-5.8 years after transplant. The recipient of the insulin-AAb-positive donor pancreas developed chronic rejection following discontinuation of immunosuppression 3.3 years after transplant. Single AAb positivity did not affect the outcome of pancreas transplantation in our study.
    Diabetes care 07/2008; 31(9):1741-2. · 7.74 Impact Factor
  • Stavros Diamantopoulos, Yong Bao
    Pediatrics in Review 10/2007; 28(9):e57-68. · 0.82 Impact Factor

Publication Stats

65 Citations
16.45 Total Impact Points

Top Journals

Institutions

  • 2007–2008
    • University of Miami
      • • Diabetes Research Institute
      • • Department of Pediatrics
      Coral Gables, FL, United States