Chimerism in organ transplantation: biological basis, immune tolerance, and diagnostic approaches

Chimerism describes the presence of genetically distinct cell populations within a single organism, originating from more than one zygote. This phenomenon can occur naturally or result from clinical interventions. It is particularly important in graft acceptance and immune tolerance after solid organ transplantation. The establishment or persistence of donor-derived cells in the recipient has been associated with modulation of alloimmune responses and may contribute to long-term graft acceptance. Chimerism monitoring, particularly after allogeneic hematopoietic stem cell transplantation, is essential for clinical management. A wide range of diagnostic techniques is used to detect chimerism, evolving from traditional cytogenetics and red blood cell phenotyping to advanced molecular assays. This review provides a focused overview of the key aspects of chimerism, including its terminology, biological mechanisms, and immunological significance in transplantation tolerance, as well as current detection methods, their analytical sensitivities, and clinical implications.

Keywords: Chimerism, chimerism monitoring, organ transplantation.