Donor selection for renal transplantation : a study on mixed lymphocyte reactions and kidney allograft survival in unimmunosuppressed dogs

The prime cause of failure of a transplanted kidney is immunological rejection of the graft. Graft rejection will not occur, when the transplanted organ is obtained from a donor which is genetically identical to the recipient (isogenic transplant). Graft rejection can always occur, when donor and recipient are genetically different (allogenic transplant). Unrelated people are always genetically different. Only when donor and recipient are monozygotic twins, complete genetic identity exists. Thus a transplanted organ will be antigenic, when donor and recipient are not monozygotic twins. The immune reaction, evoked by the antigens of such an allograft, consists of two components. In the first place, antibodies will be produced, which are specifically directed against the transplanted antigens (the so called humoral immune response). Secondly, immune reactive cells are generated, which specifically can attack the transplanted organ (the cellular immune response). The mechanism of the destruction of the allograft is complicated and only partly known. Both different types of antibodies and different types of cells are involved. Microscopically, arteritis and a cellular infiltrate can be seen (Busch et al., 1977). Progressive damaging of the glomeruli and tubuli results in a increasing loss of function of the transplanted kidney. Two factors determine the strength of the immune reaction of the recipient against the allograft. These factors are the immune response potential of the recipient and the strength of the antigenic stimulus (Lengerova, 1969). The strength of the antigenic stimulus is dependent on the immunogenetic difference between donor and recipient. Consequently, two methods are available to prevent allograft rejection, namely modification of the immune response and selection of compatible donor-recipient pairs.