regular dialysis and transplantation in Europe. Proc Eur Dial Transplant Assoc 1977; 14: 3. 16. Kramer P, Broyer M, Brunner FP, et al. Combined report of regular dialysis in Europe 1981. Proc Eur Dial Transplant Assoc 1982; 19: 4. 17. Cosio F, Alamir A, Yim S, et al. Patient survival after renal transplantation: I. The impact of dialysis pretransplant. Kid- ney Int 1998; 53: 767. 18. Asderakis A, Augustine T, Dyer P, et al. Pre-emptive kidney transplantation: the attractive alternative. Nephrol Dial Transplant 1998; 13: 1799. 19. Brand DA. Perfect timing, no remorse, and kidney transplanta- tion. Med Decis Making 1998; 18: 249. Received 18 October 1999. Accepted 15 March 2000. 0041-1337/00/7004-631/0 TRANSPLANTATION Vol. 70, 631– 640, No. 4, August 27, 2000 Copyright © 2000 by Lippincott Williams & Wilkins, Inc. Printed in U.S.A. PEPTIDE ANALOGUES AS A STRATEGY TO INDUCE TOLERANCE IN T CELLS WITH INDIRECT ALLOSPECIFICITY 1 LOREDANA FRASCA, 2,6 AYALA TAMIR, 3 STIPO JURCEVIC, 4 BARBARA MARINARI, 2 ANDREA MONIZIO, 2 ROSA SORRENTINO, 2 MAURIZIO CARBONARI, 5 ENZA PICCOLELLA, 2 ROBERT I. LECHLER, 3 AND GIOVANNA LOMBARDI 3 Department of Cell Development and Biology, and Department of Clinical Medicine, “La Sapienza” University, 1– 00185, Rome, Italy; 3 Department of Immunology, Imperial College of Medicine, Hammersmith Hospital, Department of Renal Medicine and Transplantation, Guy’s Hospital, W12 0NN London, UK Background. It has been demonstrated that indirect recognition of allogeneic MHC molecules might play an important role in provoking graft rejection. Al- though direct recognition of allogeneic molecules on antigen presenting cells of the graft may induce a state of tolerance, the continuous presentation of processed alloantigens by specialized antigen presenting cells does not allow the same phenomenon to occur. Tolerance to interleukin-2 secreting T cells can be achieved in different ways, among these is the expo- sure to mutants of the wild type allopeptide. We have investigated whether peptide analogues of the al- lopeptide can induce tolerance in T cells with indirect allospecificity. Methods. T cell clones with indirect anti-HLA-A2- specificity generated from a HLA-A2  DRB1*1502  pa- tient who chronically rejected a HLA-A2-expressing kidney allograft were used for this study. Nine peptide analogues of HLA-A2 (residues: 103–120) were pro- duced with single amino acid substitutions at the pu- tative T cell receptor for antigen contact positions. Their effect on the proliferation of a panel of T cell clones was evaluated. Results. Peptide analogues and wild type peptide had similar capacity to bind to the restriction mole- cule HLA-DRB1*1502. Co-presentation of the peptide analogues 111R/A, H, K and 114H/K, with the wild type peptide inhibited T cell responses, indicative of antag- onism. In addition, one analogue 112G/S induced un- responsiveness in the T cells to subsequent culture with the wild type peptide. Conclusions. The data presented here suggest that using reagents such as altered peptides may represent a strategy to prevent the activation of T cells with indirect alloreactivity and allograft rejection in vivo. The major obstacle to successful transplantation is the strong immune response provoked by MHC incompatible tis- sues. Underlying the strong primary immune response to MHC alloantigens is the high precursor frequency of allospe- cific T cells (1–3). This seems to be the result of direct recog- nition of intact allogeneic MHC molecules (4). Direct al- lorecognition is likely to occur predominantly during the first few months after transplantation. Once the specialized anti- gen presenting cells (APC), that is, dendritic cells (5–6), transplanted with the graft are eliminated, the direct pre- sentation of alloantigens is confined to the cells of the kidney itself. There is a large body of evidence suggesting that these cells favor the induction of hyporesponsiveness (1, 7–12). Thus, the prolonged residence of transplanted tissues has been reported to be accompanied by a fall in anti-donor T cell frequencies (13). In the absence of specialized donor-derived APC, alloantigens can be processed and presented by recip- ient APC. This has been referred to as indirect allorecogni- tion. The involvement of this pathway of allorecognition in graft rejection has been studied both in human and animal models of transplantation (14 –21). Some authors suggested 1 Giovanna Lombardi and Loredana Frasca were partially sup- ported by the National Kidney Research Fund. This work was sup- ported by the National Kidney Research Fund and by University of Rome “La Sapienza,” Ateneo Project. 2 Department of Cell Development and Biology. 3 Department of Immunology. 4 Department of Renal Medicine and Transplantation. 5 Department of Clinical Medicine. 6 Address correspondence to: Loredana Frasca, Department of Cell Development and Biology, “La Sapienza” University, Via degli Apuli, 1 - 00185, Rome, Italy. E-mail: lfrasca@axcasp.caspur.it. FRASCA ET AL. August 27, 2000 631