The role of T suppressor cells in the maintenance of spontaneously accepted orthotopic rat liver allografts.

Orthotopic liver allografts from BN donors to LEW recipients are spontaneously accepted, and the recipients develop donor-specific immunological unresponsiveness. This unresponsiveness may be mediated by suppressor T cells. Immunomagnetically purified splenic T cells from LEW rats bearing BN liver grafts were shown to adoptively transfer suppression of skin, heart, and kidney graft rejection in a donor-specific manner, prolonging the survival of BN but not third-party DA grafts. However, the suppressor T cells were sessile, being resident in the spleen but not present in thoracic duct lymph. The presence of a nonrecirculating suppressor T cell in rats spontaneously accepting liver transplants is strongly suggestive of an important function in the maintenance of donor-specific unresponsiveness, although the contribution of other possible mechanisms of unresponsiveness has not been investigated.