title: Modulation of humoral islet autoimmunity by pancreas allotransplantation influences allograft outcome in patients with type 1 diabetes.
abstract: Pancreas transplantation in patients with type 1 diabetes presents allogeneic beta-cell autoantigens to the immune system long after the initial beta-cell destruction that leads to diabetes has occurred. The aims of this study were to determine whether re-exposure to beta-cell autoantigen through transplantation affect the humoral autoimmune response and whether its modulation correlates with graft outcome. Antibodies to the major autoantigens GAD (GADA) and protein tyrosine phosphatase IA-2 (IA-2A) were measured before and after transplantation in patients with type 1 diabetes who received pancreas and kidney allografts. In the 110 cases studied, pancreas graft survival was not significantly associated with the presence of GADA or IA-2A before transplantation. In the 75 patients with sequential follow-up samples up to 11.2 years after transplantation, autoantibodies were persistently undetectable in 44 cases (59%) and remained at stable detectable levels in 13 cases (17%). Substantial changes in antibody levels were found in 18 cases (24%), of which 13 cases (17%) had declining levels and 5 cases (7%) had marked increments after transplantation. Rising GADA and IA-2A levels in these five patients were predominantly of the IgG1 subclass, with progressive spreading of epitope reactivity. Pancreas graft function was lost 0.7-2.3 years after rising autoantibody levels in four of these five patients, and a significantly lower pancreas graft survival was found in patients with major rises in either GADA or IA-2A levels (P < 0.0001 vs. the remainder) and in patients having persistently high levels of IA-2A (P = 0.002 vs. stable antibody-negative patients). Kidney graft survival was not associated with islet autoantibody status. In conclusion, a minority of patients receiving pancreas allografts under generalized immunosuppression show a stimulation of islet autoantibody reactivity characteristic of that found in preclinical type 1 diabetes, which is almost invariably followed by graft function failure and resumption of insulin therapy.
authors.affiliation: Department of Medicine, Istituto Scientifico San Raffaele, San Raffaele Vita-Salute University, Milan, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Braghi
authors.forename: E
authors.initials: E
authors.lastname: Bonifacio
authors.forename: A
authors.initials: A
authors.lastname: Secchi
authors.forename: V
authors.initials: V
authors.lastname: Di Carlo
authors.forename: G
authors.initials: G
authors.lastname: Pozza
authors.forename: E
authors.initials: E
authors.lastname: Bosi
mesh_terms: D000328:Adult; D000917:Antibody Formation; D001323:Autoantibodies / Q000032:analysis / Q000145:classification / Q000276:immunology; D001324:Autoantigens / Q000032:analysis; D015551:Autoimmunity / Q000276:immunology*; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology* / Q000601:surgery*; D000939:Epitopes / Q000276:immunology; D005968:Glutamate Decarboxylase / Q000276:immunology; D006085:Graft Survival / Q000276:immunology; D006801:Humans; D008875:Middle Aged; D016035:Pancreas Transplantation / Q000276:immunology*; D011184:Postoperative Period; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000276:immunology; D014184:Transplantation, Homologous; D016896:Treatment Outcome
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D000939:Epitopes; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D005968:Glutamate Decarboxylase