This paper describes an enquiry into the possibility of inducing transplantation tolerance in adult mice by combining a number of wellrecognized immunological depressants with an administration of antigen in a nonsensitizing form.
In the context of transplantation research the antigen used to procure tolerance has almost invariably taken the form of a suspension or brei containing viable donor cells (or cells syngeneic with the donor's). This is objectionable for several reasons. Living cells normally sensitize adult recipients and so shorten the life of future homografts; it would be preferable on almost all counts to administer antigen in such a way that, while it retained other manifestations of its antigenic power— particularly the power to induce tolerance—it did not excite transplantation immunity. Again, for more or less compelling reasons, the cells used to establish tolerance normally consist of, or contain, lymphoid cells. This confuses the interpretation of any state of tolerance