ABSTRACT
This chapter reviews the work in which the chicken has been used as the experimental model to address the cell-mediated mechanisms that may be involved in immunological tolerance. It demonstrates a failure to respond to an antigen (tolerogen) because of an inability of any specific cell that is part of the immune system to react to that antigen. Although several reports cited suggest that recognition of self major histocompatibility complex (MHC) occurs by the interaction of developing thymocytes with cortical epithelial cells, recent additional data provides evidence that other thymic cells play a significant role in mice. Many of the experiments demonstrate the understanding of the mechanism(s) involved in immunological tolerance is important and interesting in its own right, it has also served as a useful model to study other immunological phenomena. Although a review has emphasized clonal deletion as the likely mechanism for the removal of self-reactive clones, autologous mixed lymphocyte reactions (MLR) and autoreactive clones can be demonstrated.
