Eighty-six infants born without a thymus have been treated with allogeneic cultured thymus tissue implantation (CTTI). These infants, who lack T cells and are profoundly immunodeficient at birth, after CTTI from an unmatched donor develop T cells similar to those of recipient that are tolerant to both their own major histocompatibility antigens and those of the donor. We tested use of CTTI with the goal of inducing tolerance to unmatched heart transplants in immunocompetent rats. We thymectomized and T cell–depleted Lewis rats. The rats were then given cultured thymus tissue from F1 (Lewis × Dark Agouti ) under the kidney capsule and vascularized Dark Agouti (DA) heart transplants in the abdomen. Cyclosporine was administered for 4 months. The control group did not receive CTTI. Recipients with CTTI showed repopulation of naive and recent thymic emigrant CD4 T cells; controls had none. Recipients of CTTI did not reject DA cardiac allografts. Control animals did not reject DA grafts, due to lack of functional T cells. To confirm donor-specific unresponsiveness, MHC-mismatched Brown Norway (BN) hearts were transplanted 6 months after the initial DA heart transplant. LW rats with LWxDA CTTI rejected the third-party BN hearts (mean survival time 10 days); controls did not. CTTI recipients produced antibody against third-party BN donor but not against the DA thymus donor, demonstrating humoral donor-specific tolerance. Taken together, F1(LWxDA) CTTI given to Lewis rats resulted in specific tolerance to the allogeneic DA MHC expressed in the donor thymus, with resulting long-term survival of DA heart transplants after withdrawal of all immunosuppression.
Jean Kwun, Jie Li, Clay Rouse, Jae Berm Park, Alton B. Farris, Maragatha Kuchibhatla, Joseph W. Turek, Stuart J. Knechtle, Allan D. Kirk, M. Louise Markert
Guidelines: The Editorial Board will only consider letters that we deem relevant and of interest to our readers. We will not post data that have not been subjected to peer review, nor will we post letters that are essentially a reiteration of another letter. We reserve the right to edit any letter for length, content, and clarity. Authors will be notified by e-mail if their letters were accepted. No appeals will be considered.
Specific requirements: All letters must be 400 words or fewer. You may enter the letter as plain text or HTML. The author's name and e-mail address are required, and will be posted with the letter. All possible conflicts of interest must be noted, even if they are not posted. If you wish to include a figure (keep in mind that non-peer-reviewed data will not be posted), please contact the editors directly at email@example.com.