Composite Tissue Allotransplantation Immunology

Composite tissue allotransplantation (CTA) is an option recently introduced for major reconstruction of tissue defects. Since announcements of successful hand, larynx, knee, muscle, nerve, abdominal wall and, most recently, partial face transplantation, CTA has become one of the techniques used by plastic and reconstructive surgeons [1]. Clinical success in CTA is the culmination of progress in two disparate surgical disciplines: replantation and organ transplantation, a close collaboration between plastic and transplant surgeons. This joining of reconstructive and transplant surgery forces the movement of hand and facial tissue allotransplantation into the clinical arena [2]. Translation to the clinical field has shown that CTA is a viable treatment option for those who have lost extremities and suffered large tissue defects [3-5]. As with other allografts, CTA can undergo immune-mediated rejection. When compared with solid organ transplants, composite tissue allografts are histologically heterogeneous, composed of different tissue types (e.g., skin, muscle, bone, bone marrow, lymph nodes, nerve, and tendon), and express different immunogenicity of transplanted elements [6]. Currently, the most important issue for routine application of CTA to clinical practice is the need for lifelong immunosuppression [7]. The immunosuppression medications used to prevent tissue rejection in CTA are the same as those used in tens of thousands of solid organ transplant recipients. The toxicity of chronic, nonspecific immunosuppression remains a major limitation to the wideCONTINUING MEDICAL EDUCATION