The role of complement in transplantation

The complement system contributes critically to the barrier to transplantat ion of cells and organs. In the case of tissues and organs transplanted bet ween individuals of the same species, that is in allotransplantation, the b arrier posed by complement is seemingly eclipsed by the barrier posed by ce llular immune responses. In the case of cells and organs transplanted betwe en individuals of disparate species, that is xenotransplantation, the compl ement system has been thought to pose a nearly insurmountable barrier. With our understanding on how the complement system contributes to rejection, i t is now clear that the complement system is more important in allotranspla ntation and more forgiving in xenotransplantation than was previously thoug ht. (C) 1999 Elsevier Science Ltd. All rights reserved.