The Significance of the Variety of Mechanisms of Allograft Tolerance

Abstract

Summary. The influence of variations in protocol on the induction and early stages of maintenance of allograft tolerance in neonatal rats was studied. Allogeneic bone marrow cells, the anti-recipient activity of which was specifically reduced because of their origin from immunologically tolerant donors, possessed diminished tolerogenic capacity. This was commonly manifested by development of an unreactive state in only one of the two parameters of reactivity-allograft rejection and graft-versus-host reactivity-that were monitored. A similar deviation from the occurrence of unreactivity in both forms that characterizes tolerant rats was observed in animals which had been inoculated with syngeneic thymus cells at the time of induction of tolerance. Attempts to demonstrate a requirement for an extended period of exposure of young rats to semi-allogeneic bone marrow cells before specific unreactivity on the part of host cells became irreversible were unsuccessful.

Cellular Immune Recognition and the Biological Role of Major Transplantation Antigens

“…Our results were not the only ones that hinted at the biological role of major transplantation antigens, and they fitted several observations made during 1972/73. In addition to the suggestions from cytotoxic T-cell studies with leukaemia, ectromelia and LCM viruses [9, 40, 41, 41a] [43,44]. In parallel experiments with inbred strains of guinea pigs, A. S. Rosenthal and E. M. Shevach analysed antigen-specific prolifera-tive T-cell responses and found them only when primed T-cells and antigen-presenting cells were from guinea pigs with the same MHC type [45].…”