Suppressor cells and their role in the survival of immunologically enhanced rat kidney allografts.

A search has been made for suppressor cells in the spleens of AS rats bearing long-surviving, enhanced AUG strain kidney allografts. The assay consisted of an adoptive transfer of splenocytes from AS rats with enhanced AUG kidneys to normal AS rats that also received test grafts of AUG kidneys. The critical feature of the AUG kidney test grafts was that the native population of passenger cells had been replaced by AS passenger cells--thus reducing, but not eliminating, immunogenicity of the graft. With this assay, it was shown that 2.7-3.5 X 10(8) spleen cells transferred substantial and statistically significant suppression of graft rejection. Suppression was also transferred by spleen cells that did not adhere to nylon wool. It is concluded that suppressor cells are one of the mechanisms ensuring continued survival of enhanced kidney allografts.