title: Role of persistence of antigen and indirect recognition in the maintenance of tolerance to renal allografts.
abstract: BACKGROUND
  We have previously shown that a 12-day treatment with cyclosporine A (CyA) facilitates induction of tolerance to class-I disparate kidneys, as demonstrated by acceptance of second, donor-matched kidneys without immunosuppression. In the present study, we have examined 1) the duration of tolerance in the absence of donor antigen and 2) the pathway of antigen recognition determining maintenance or loss of tolerance.
  
  
  METHODS
  Seventeen miniature swine received class-I mismatched kidneys with 12 days of CyA, and received second donor-matched kidneys without immunosuppression at 0, 1, 3, or 4 months after nephrectomy of the primary graft. Five were sensitized 6 weeks after nephrectomy of the primary graft, three with donor-matched skin grafts, and two with donor class-I peptides to eliminate direct pathway involvement. In addition, two long-term tolerant animals received class-I peptides.
  
  
  RESULTS
  Rejection of second grafts required at least a 3 month absence of donor antigen. Although donor-matched skin grafts in animals tolerant to kidneys induced antidonor cytotoxic T lymphocyte responses, second renal transplants revealed no evidence of sensitization. In contrast, immunization of recipients with donor class-I peptides after nephrectomy of the primary graft led to loss of tolerance at both T-cell and B-cell levels, as evidenced by rejection of the second graft in 5 days and development of antidonor immunoglobulin G. Peptide immunization of long-term tolerant in recipients bearing long-term renal grafts did not break tolerance.
  
  
  CONCLUSIONS
  These data indicate that the renal allograft is required for the indefinite maintenance of tolerance, that indirect antigen presentation is capable of breaking tolerance, and that in tolerant animals, direct antigen presentation may suppress rejection, allowing tolerance to persist.
authors.affiliation: Transplantation Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Okumi
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Fishbein
authors.forename: Adam D
authors.initials: AD
authors.lastname: Griesemer
authors.forename: Pierre R
authors.initials: PR
authors.lastname: Gianello
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hirakata
authors.forename: Shuji
authors.initials: S
authors.lastname: Nobori
authors.forename: Shannon
authors.initials: S
authors.lastname: Moran
authors.forename: Emma
authors.initials: E
authors.lastname: Samelson-Jones
authors.forename: Akira
authors.initials: A
authors.lastname: Shimizu
authors.forename: David H
authors.initials: DH
authors.lastname: Sachs
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Yamada
mesh_terms: D000818:Animals; D007108:Immune Tolerance; D007519:Isoantigens / Q000276:immunology*; D016030:Kidney Transplantation / Q000276:immunology* / Q000473:pathology; D007959:Lymphocyte Culture Test, Mixed; D008214:Lymphocytes / Q000276:immunology; D023421:Models, Animal; D012086:Reoperation; D016038:Skin Transplantation / Q000276:immunology* / Q000473:pathology; D013552:Swine; D013556:Swine, Miniature; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014184:Transplantation, Homologous / Q000276:immunology / Q000473:pathology
chemical_list: D007519:Isoantigens