Allograft Rejection - Fact and Fancy

Abstract

Only within the past few decades have immunobiologists begun to appreciate the full complexities of allograft rejection, that dramatic multifaceted and powerful cascade of host responses that are called into play by and lead to the destruction of genetically dissimilar tissues and organs. The modern era of transplantation biology opened during World War II when Medawar initiated studies of the behavior of skin allografts, first on burned airmen then on rabbits, nothing that the progressive infiltration of the graft by lymphocytes and macrophages presaged graft destruction (Medawar, 1956–1957). He also showed that the destruction of a second set of skin grafts was accelerated after transplantation to animals, which had previously rejected skin from the same donor, concluding that the host had become sensitized selectively against the antigen. About the same time, the development of inbred murine strains provided opportunities to perform reproducible and well-controlled investigations into this burgeoning biology. Mitchinson (1954) and Billingham et al. (1954) used such strains to demonstrate that the immunity of animals sensitized to a tumor or skin graft could be conferred by transfer of lymphoid cells to syngeneic hosts. Using inbred rats, Gowans et al. (1962) then showed that small lymphocytes recirculated and were the prototypic immunologically competent cells.