If we could induce tolerance in adults, this would have obvious benefits in transplantation and the treatment of autoimmunity. Much effort has therefore been expended towards this goal. Indeed a number of regimes have been successfully applied under experimental conditions and with particular antigens. A clinically usable protocol is still elusive however. It will suffice here to give just two examples of tolerising conditions which have worked.
Peptide sniffing (inhalation tolerance)
If immunogenic (that is MHC binding) peptides are aerosolised and administered via the nostrils to mice, the animals can be rendered tolerant to immunogenic challenge with the same peptide (ie given subcutaneously in adjuvant).
Co-receptor blockade
The use of monoclonal antibodies to any of the important co-receptors, CD4/8, B7, CD40 where a particular response is dependent on the blockaded co-receptor can lead to the development of tolerance.
Information provided by: http://www-immuno.path.cam.ac.uk