Phylogeny of Functional Humoral Transplantation Immunity: Comparative Studies in Amphibians and Rodents

Abstract

Mammalian transplantation alloantigens elicit complex immunoprotective and immunodestructive reactivities which can be demonstrated in vitro by cytotoxicity and blocking assays (1). The impact of these functionally disparate responses on the in vivo fate of transplants has been strongly evidenced by the dramatically prolonged (enhanced) survival or by the significantly accelerated rejection of test skin grafts on mice adoptively immunized with immune lymphoid cells or sera (2–4). In marked contrast to our emerging awareness that for mammals, the survival of allografts reflects a net immune response equal to the outcome of a dynamic balance between functionally opposing immune reactivities (5), has been our relative ignorance of whether humoral immunity plays a comparable role in regulating graft survival in ectothermic (cold-blooded) vertebrates. Indeed, we are cognizant of only a limited number of reports that transplants do evoke detectable alloantibodies in fish (6), salamanders (7) and frogs (8).