Prolonged survival of fully allogeneic cardiac grafts in naive mice and those with sensitization induced by antigen delivery through the respiratory tract

Nonresponsiveness to protein antigen induced by administration of the antigen through the alimentary or respiratory tract is well known as mucosal tolerance. We previously reported in this Journal that donor splenocytes delivered orally induce prolonged survival of fully allogeneic cardiac grafts and generate regulatory cells when delivered with a nondepleting anti-CD4 monoclonal antibody. Therefore, in this study we examined whether intratracheal delivery of alloantigen could induce prolonged survival of fully mismatched allogeneic cardiac grafts and regulatory cells.